Effect of renal perfusion pressure on excretion of calcium, magnesium, and phosphate in the rat

Abnormalities in renal handling of calcium, magnesium, or phosphate have been implicated in the development and/or maintenance of human hypertension. We have shown recently that renal excretion of these ions is correlated to blood pressure in Dahl salt-sensitive as well as salt-resistant rats. The present study was designed to determine whether renal perfusion pressure per se could affect excretion of these ions. Urinary excretion of calcium, magnesium, and phosphate was studied in anaesthetized Sprague-Dawley rats under basal conditions and during an intravenous infusion of angiotensin II (ANG II), vasopressin (AVP) or phenylephrine (PE). A cuff, placed around the aorta between the two renal arteries, allowed maintenance of normal perfusion pressure in the left kidney, while that in the right kidney was allowed to rise. Infusion of pressor agents raised mean arterial blood pressure to comparable levels (means +/- SE): ANG II (n = 7), before = 102 +/- 4, during = 133 +/- 3 mmHg, AVP (n = 8), before = 110 +/- 7, during = 136 +/- 5 mmHg, PE (n = 6), before = 111 +/- 6, during = 141 +/- 6 mmHg. Although there was no difference in excretion of calcium, magnesium and phosphate between the two kidneys under basal conditions, infusion of ANG II or PE induced hypercalciuria, hypermagnesiuria and hyperphosphaturia in the right kidney which was exposed to the increased arterial pressure. Such effects did not appear in the pressure-controlled left kidney. Infusion of AVP was associated with reduced excretion of calcium and magnesium, and increased excretion of phosphate, in the normotensive kidney. The response to the similarly increased renal perfusion pressure in this group was also reduced for calcium and magnesium, and enhanced for phosphate. The results indicate (1) renal excretion of calcium, magnesium and phosphate is renal perfusion pressure-dependent; the higher the renal perfusion pressure, the greater the excretion of these ions. (2) Independently of perfusion pressure, AVP can inhibit phosphate reabsorption and stimulate divalent cation reabsorption.     

ICAM-1 antisense oligodesoxynucleotides prevent reperfusion injury and enhance immediate graft function in renal transplantation

BACKGROUND: Ischemia-reperfusion injury after organ transplantation is a major cause of delayed graft function. We showed earlier that antisense oligodesoxynucleotides (ODN) for intercellular adhesion molecule-1 (ICAM-1) ameliorate reperfusion injury after acute ischemia. This study tested the hypothesis that antisense ODN for ICAM-1 prevents ischemia-reperfusion injury and facilitates immediate graft function in a rat autotransplantation model. METHODS: Both kidneys were removed from male Lewis rats and re-implanted the left kidney after 30 minutes of cold ischemia time. The warm ischemia time was 60 minutes. Sham operated, uninephrectomized animals served as controls for renal function and histology. ICAM-1 antisense ODN (5 mg/kg), reverse ODN, or saline-vehicle were administered to donor animals i.v. six hours before autotransplantation. Glomerular filtration rate (insulin clearance), and serum creatinine concentrations were measured 24 hours post-transplantation. Tubular necrosis severity was assessed by histological grading scale. ICAM-1 expression was determined by immunohistochemistry and Western blot. RESULTS: Antisense ODN decreased ICAM-1 expression and leukocyte infiltration significant. Antisense ODN-treated animals showed significantly less tubular necrosis, than controls. Serum creatinine of antisense ODN-treated animals (N = 6) was 0.55 +/- 0.02 mg/dl compared to 1.92 +/- 0.07 mg/dl in reverse ODN-treated controls (N = 6; P < 0.01), 24 hours after transplantation. Antisense ODN-treated animals had normal GFR (0.93 +/- 0.07 ml/min/kidney wt) compared to sham-operated animals (0.95 +/- 0.09 ml/min/kidney wt), while autotransplanted animals treated with reverse ODN or saline-vehicle were all anuric. The ischemia-reperfusion-induced up-regulation of MHC class II was totally prevented by antisense ODN. CONCLUSIONS: ICAM-1 inhibition ameliorates ischemia-reperfusion injury and prevents delayed graft function. Antisense ODN-treatment of donors or donor organs for ICAM-1 may be useful for the prevention of reperfusion injury in human renal transplantation.     

Effects of antioxidant vitamins on renal and hepatic erythropoietin production

An important role in O2 sensing has been assigned to microsomal and membrane-bound b-type cytochromes which generate regulatory reactive O2 species (ROS). Recently, ROS have been shown to suppress the in vitro synthesis of erythropoietin (Epo). We investigated the potential of the antioxidant vitamins A, E and C to enhance renal and hepatic Epo production. Renal effects were studied in isolated serum-free perfused rat kidneys. In control experiments without antioxidant vitamins, Epo secretion amounted to 441 +/- 23 mU/g kidney (mean +/- SEM, N = 5) during the three hour period of hypoxic perfusion (arterial pO2 35 mm Hg). Epo secretion significantly increased to 674 +/- 92 mU/g kidney (N = 7) when vitamins A (0.5 microgram/ml), E (0.5 microgram/ml) and C (10 micrograms/ml) in combination were added to the perfusion medium. The effects of the single vitamins were studied in Epo-producing hepatoma cell cultures (lines HepG2 and Hep3B). Vitamin A induced a dose-dependent increase (half-maximal stimulation at 0.2 microgram/ml) in the production of immunoreactive Epo during 24 hours of incubation (such as 680 +/- 51 U Epo/g cell protein in HepG2 cultures with 3 micrograms/ml retinol acetate compared to 261 +/- 15 U/g in untreated controls; N = 4). In contrast, vitamin E (tested from 0.05 to 500 micrograms/ml) and vitamin C (tested from 2 to 200 micrograms/ml) did not increase Epo production in hepatoma cell cultures. Thus, while vitamins E and C may have the potential to protect cells from oxidative damage, vitamin A exerts a specific stimulation of Epo production. Preliminary evidence suggests that this effect of vitamin A involves increased mRNA levels of hypoxia-inducible factor 1 alpha (HIF-1 alpha).     

Control of monocyte influx in glomerulonephritis in transplanted kidneys in the rat

Induction of anti-Thy-1 nephritis in different strains of inbred rats results in phenotypically different types of renal diseases. In Wistar and Lewis (LEW) rats, a transient influx of ED1+ macrophages occurs 24 hours after injection of anti-Thy-1 antibodies, whereas this does not occur in F344 rats. The present experiments were designed to investigate the role of the kidney in the regulation of the monocyte influx in this model. To dissociate the role of the immune system from local intrarenal factors in the control of monocyte influx, anti-Thy-1 nephritis was induced in LEW rats with an F344 kidney transplant and in F344 rats with a LEW kidney allograft. Acute rejection episodes were prevented by treatment with an anti-CD4 monoclonal antibody. Control rats received a syngeneic kidney graft. Monocyte influx after injection of anti-Thy-1 antibodies was found in the glomeruli of both LEW and F344 kidneys removed from LEW recipients, whereas there was no demonstrable monocyte influx after infusion of anti-Thy-1 antibodies in either LEW or F344 kidneys removed from F344 recipients. Monocyte infiltration correlated with the subsequent expansion of the mesangial extracellular matrix. The inability to attract monocytes was not due to the lack of glomerular expression of chemokines, because F344 and LEW glomeruli demonstrated a similar expression of monocyte chemoattractant protein-1 (MCP-1). Differences in the ability to activate the complement system were excluded. We conclude that the immune system controls the glomerular influx of monocytes and that the reaction of the mesangial cells is probably controlled by combinations of cytokines produced during the inflammatory process.     

Measurement of renal vein blood flow in rats by high-field magnetic resonance

The aim of the present study was to examine whether magnetic resonance imaging (MRI) based method for non-invasive in vivo measurement of vein blood flow in rats could be used to estimate renal blood flow (RBF). Measurements were performed using a high-field (7 Tesla) MRI scanner with a short echo time phase contrast velocity measurement pulse sequence. The method was evaluated in vitro by flow measurements in an acrylic pipe and in vivo by recording left renal vein blood flow in normal and unilaterally nephrectomized rats. In a subset of animals RBF was measured by a direct method using 14C-tetraethylammoniumbromide. In vitro a high accuracy was found between applied and MRI measured flow rates in the range from 0.5 to 33 ml/min (r = 0.997; P < 0.001). In vivo the MRI measured left renal vein blood flow was 70% higher in unilaterally nephrectomized animals compared to control animals (3.4 +/- 0.4 ml/min/ 100 g body wt vs. 2.0 +/- 0.1 ml/min/100 g body wt, P < 0.001). Direct measurements of RBF revealed comparable values (3.4 +/- 0.3 ml/min/100 g body wt vs. 2.3 +/- 0.4 ml/min/100 g body wt, P = 0.05). In addition, the left kidney volume was recorded by MRI with an increase amounting to 40% (1.18 +/- 0.05 ml vs. 0.84 +/- 0.02 ml; P < 0.001) in the nephrectomized group compared to controls. Finally, a positive correlation was seen between left renal vein blood flow and MRI measured renal volume (r = 0.91; P < 0.001). In summary, MRI is a non-invasive tool by which measurement of renal vein blood flow can be performed, and it is concluded that MRI-based renal vein flow measurements can be used to estimate RBF in small rodents.     

Direct measurement of steroid sulfate and glucuronide conjugates with high-performance liquid chromatography-mass spectrometry

Laser Doppler flowmetry (LDF) is a sensitive method for the measurement of microvascular blood flow in tissue. The method has been found useful for estimating skin, liver, or gastrointestinal blood flow. Whether it can be applied laparoscopically and whether it is able to measure the intraparenchymal blood flow of an intraabdominal organ is still unknown. In a pilot study, 6 pigs received a laparotomy for placement of a 19-gauge LDF needle probe into the renal parenchyma. Three different locations of the lower pole kidney were chosen for the blood flow measurement. The reliability of using the instrument to measure the renal tissue blood flow was assessed by comparison of the results of renal arterial blood flow obtained from a well-established methodology--ultrasonic Doppler flowmetry. Recordings were taken following (a) intravenous administration of 0.005 mg/kg norepinephrine, (b) manual compression of the suprarenal aorta, and (c) intravenous injection of a lethal dose of phenobarbital (50 mg/kg). Measurements of LDF were possible in all kidney units. The renal tissue perfusion detected by LDF correlated excellently with the renal arterial blood flow under different renal perfusion pressures. The feasibility of using LDF probe to measure the renal tissue perfusion in a laparoscopic model was then assessed in 15 pigs. Under pneumoperitoneum, the right kidneys were approached transperitoneally with the animal in the decubitus position. A total of three trocars were used. The peritoneum and Gerota's fascia were incised and the LDF needle probe was manipulated and inserted by an endoforceps into the renal tissue via a 5-mm trocar. The insertion of the LDF needle probe was technically feasible in all 15 kidney units, and the depth of insertion could be adjusted under direct vision. Baseline values for the renal cortical and renal medullary blood flow were 50.1 +/- 17.7 and 8.8 +/- 3.3 ml/min/100 g tissue, respectively. Spatial variations of the LDF measurements averaged 6%, and temporal variations over 15 min averaged 5%. Four additional hemodynamic parameters were simultaneously recorded, including left carotid artery blood flow, aortic blood pressure, inferior vena caval pressure, and intraabdominal pressure. It appears that systemic and renal hemodynamic parameters can be monitored reliably and continuously in the porcine model. This method allows further information concerning hemodynamic changes and safety of laparoscopy to be obtained.     

Influence of nitric oxide in the chronic phase of two-kidney, one clip renovascular hypertension

Chronic two-kidney, one clip (2K1C) renovascular hypertension is characterized by a largely angiotensin-independent elevated blood pressure (BP). We hypothesized that the long-term effect of hypertension would compromise endothelium-derived nitric oxide (NO) and diminish its influence in controlling renal perfusion. We determined the influence of endothelium-derived NO on renal hemodynamics and the angiotensin-NO interaction regulation of renal perfusion in rats with chronic 2K1C hypertension. Renal blood flow (RBF) was measured by radioactive microspheres in rats with either early-phase (4 weeks after clipping, n=7) or chronic-phase (13 to 16 weeks after clipping, n=7) 2K1C hypertension. The systemic and renal response to NO synthesis inhibition was determined with 10 mg/kg body wt N omega-nitro-L-arginine methyl ester (L-NAME). In rats with early-phase 2K1C hypertension, BP was 149+/-3 mm Hg, which increased by 42+/-3 mm Hg with L-NAME (P<.001). L-NAME decreased RBF by 20% (P<.02) and 17% (P<.005) and increased renal vascular resistance (RVR) by 58% (P<.005) and 62% (P<.02) in the nonclipped and clipped kidneys, respectively. In rats with chronic 2K1C hypertension, BP was 166+/-3 mm Hg, and L-NAME increased this by 35+/-6 mm Hg (P<.001). In the nonclipped and clipped kidneys of chronic 2K1C hypertensive rats, L-NAME decreased RBF by 20% (P<.01) and 17% (P<.01) and increased RVR by 51% (P<.005) and 60% (P<.02), respectively. There were no differences in L-NAME-induced changes between early- and chronic-phase 2K1C hypertensive rats. Next, we treated seven chronic-phase 2K1C hypertensive rats with 10 mg/kg body wt losartan, which reduced BP by only 7.7% (P<.005). After losartan, L-NAME increased BP by 41+/-3 mm Hg (P<.001), decreased RBF to the nonclipped kidney by 44% (P<.05), and increased RVR by 110% (P<.005); the decrease in RBF was significantly greater compared with untreated chronic-phase controls (P<.05). In the clipped kidney, L-NAME decreased RBF by 26% (P<.05) and increased RVR by 76% (P <.05). Thus, angiotensin blockade did not attenuate the systemic or renal vasoconstriction to L-NAME. Our results suggest that in both early and chronic phases of 2K1C hypertension, NO contributes significant dilator tone to buffer the hypertension and maintains perfusion of both kidneys by counterbalancing angiotensin-independent vasoconstriction.     

3D time-resolved contrast-enhanced MR DSA: advantages and tradeoffs

To test whether renal V1-receptors selectively influence blood flow in the renal medulla, we compared the effects of infusion of [Phe2,Ile3,Orn8]vasopressin (3-30 ng/kg/min) by the intravenous, renal arterial, and renal medullary interstitial routes in anesthetized rabbits. Intravenous [Phe2,Ile3,Orn8]vasopressin (30 ng/kg/min) reduced renal medullary perfusion (MBF) by 36 +/- 5% but did not significantly affect cortical perfusion (CBF). MBF was also reduced with the renal arterial (35 +/- 5%) and renal medullary interstitial (40 +/- 7%) routes but, in contrast to the intravenous infusion, CBF was also reduced, by 21 +/- 3% and 15 +/- 3%, respectively. Urine flow and sodium excretion were increased by [Phe2,Ile3,Orn8]vasopressin, and with direct intrarenal administration, this effect was similar for both the infused (left) and noninfused (right) kidneys. After a 20-min renal medullary interstitial infusion of [3H]norepinephrine, radiolabel concentration was approximately fivefold greater in the left medulla than in the left cortex. We conclude that [Phe2,Ile3,Orn8]vasopressin acts on V1-receptors to alter regional kidney blood flow and tubular salt and water handling. The V1-receptors involved are almost certainly within the kidney itself, but given the contrasting effects of the different infusion routes on MBF and CBF, we cannot exclude the possibility that some of the observed effects of [Phe2,Ile3,Orn8]vasopressin are mediated by activation of extra-renal V1-receptors.     

Candesartan cilexetil reduces chronic renal allograft injury in Fisher-->Lewis rats

OBJECTIVES: To determine the effects of the angiotensin II receptor antagonist, candesartan cilexetil, on glomerular and systemic blood pressures and the development of renal injury in Lewis rat recipients of a single Fisher kidney (F334--> LEW transplantation), an established rat model of chronic renal allograft failure. DESIGN: Recent studies have shown that chronic injury of renal allografts in F334-->LEW rats may be virtually abrogated by supplying the Lewis recipients with two Fisher kidneys or, alternatively, by retaining a native kidney. These findings imply a major contribution from processes associated with nephron loss to the pathogenesis of chronic renal allograft failure, a notion supported by the observation that transplanting two kidneys also normalizes glomerular capillary pressure (PGC) in F344-->LEW rats. Thus, a pharmacological reduction in PGC, by blocking the effects of angiotensin II, should also lessen renal injury in F344-->LEW rats. MATERIALS AND METHODS: Bilaterally nephrectomized F344--> LEW rats were treated with the angiotensin II receptor blocker candesartan cilexetil (TCV-116) at 40 mg/l or with vehicle, administered in drinking water. Proteinuria and systolic blood pressure were assessed monthly, and histological studies were carried out after 24 weeks. The glomerular filtration rate and glomerular pressures were determined after 10 weeks in additional rats by clearance and micropuncture studies. RESULTS: Treatment with candesartan cilexetil lowered systemic blood pressure, normalized PGC at 10 weeks and greatly reduced proteinuria and allograft glomerulosclerosis at 24 weeks. CONCLUSIONS: These data indicate that the development of renal injury in F344-->LEW renal allografts can be prevented by the pharmacological blockade of angiotensin II receptors using candesartan cilexetil. This suggests that angiotensin-dependent processes contribute significantly to chronic injury in this model of late renal allograft failure.     

Induction of macrophage migration inhibitory factor messenger ribonucleic acid in rat forebrain by reperfusion

To evaluate the impact of uremia and associated caloric restriction on physiologically pulsatile growth hormone (GH) release, we used deconvolution analysis of spontaneous plasma GH profiles in 5/6-nephrectomized male rats (NX, N = 9). Three different normal renal function sham-operated groups were used: rats fed a normal diet ad libitum (SAL, N = 9); NX pair-fed rats (SPF, N = 6); NX rats pair-fed for protein ingestion but calorically supplemented up to the energy intake of SAL (SPF+, N = 8). Severe renal failure was confirmed by much higher (P < 0.001) BUN in NX than sham groups. NX rats were growth retarded as shown by reduced (P < 0.01) weight and length gains as compared with sham animals. Deconvolution analysis (mean +/- SEM) of plasma samples obtained every 10 minutes over 6 hours, and 14 to 16 days after second stage nephrectomy showed that NX rats had a longer GH t(1/2) (17.0 +/- 1.8 vs. 11.6 +/- 0.8 min), less GH mass secreted per burst (48 +/- 15 vs. 95 +/- 16 ng/ml/pulse), lower secretory pulse amplitude (1.9 +/- 0.5 vs. 5.8 +/- 0.9 ng/ml/min), and a reduced total GH secretion (240 +/- 69 vs. 400 +/- 56 ng/ml/6 hr) than SAL rats. Corresponding data were not significantly different between NX and SPF, or between SAL and SPF+ groups. In summary, stunted rats with chronic renal failure exhibit a prolonged GH t(1/2) and suppression of GH secretory pattern burst mass. Control data from rats with normal renal function suggest that the amplitude-specific depression of GH secretion may be attributed, at least in part, to chronic renal failure-associated calorie deficiency.     

Renal vascular responses to angiotensin II in conscious spontaneously hypertensive and normotensive rats

It has been postulated that exaggerated renal sensitivity to angiotensin II may be involved in the development and maintenance of hypertension in the spontaneously hypertensive rat (SHR). The purpose of this study was to compare the renal vascular responses to short-term angiotensin II infusions (50 ng/kg/min, i.v.) in conscious SHRs and Wistar-Kyoto (WKY) rats. Renal cortical blood flow was measured in conscious rats by using quantitative renal perfusion imaging by magnetic resonance, and blood pressure was measured by an indwelling carotid catheter attached to a digital blood pressure analyzer. Renal vascular responses to angiotensin II were similar in control SHRs and WKY rats. Pretreatment with captopril to block endogenous production of angiotensin II significantly augmented the renal vascular response to exogenous angiotensin II in the SHRs but not in the WKY rats. The renal vascular responses to angiotensin II were significantly greater in captopril-pretreated SHRs than in WKY rats (cortical blood flow decreased by 1.66 +/- 0.13 ml/min/g cortex in WKY rats compared with 2.15 +/- 0.14 ml/min/g cortex in SHR; cortical vascular resistance increased by 10.5 +/- 1.4 mm Hg/ml/min/g cortex in WKY rats compared with 15.6 +/- 1.7 mm Hg/ml/min/g cortex in SHRs). Responses to angiotensin II were completely blocked in both strains by pretreatment with the angiotensin II AT1-receptor antagonist losartan. Results from this study in conscious rats confirm previous findings in anesthetized rats that (a) the short-term pressor and renal vascular responses to angiotensin II are mediated by the AT1 receptor in both SHRs and WKY rats, and (b) the renal vascular responses to angiotensin II are enhanced in SHRs compared with WKY rats when endogenous production of angiotensin II is inhibited by captopril pretreatment.     

Public health developments in colonial Malaya: colonialism and the politics of prevention

-Previous studies have shown that whereas the nonclipped kidney in two-kidney, one clip (2K1C) rats undergoes marked depletion of renin content and renin mRNA, intrarenal angiotensin II (Ang II) levels are not suppressed; however, the distribution and functional consequences of intrarenal Ang II remain unclear. The present study was performed to assess the plasma, kidney, and proximal tubular fluid levels of Ang II and the renal responses to intrarenal Ang II blockade in the nonclipped kidneys of rats clipped for 3 weeks. The Ang II concentrations in proximal tubular fluid averaged 9.19+/-1.06 pmol/mL, whereas plasma Ang II levels averaged 483+/-55 fmol/mL and kidney Ang II content averaged 650+/-66 fmol/g. Thus, as found in kidneys from normal rats with normal renin levels, proximal tubular fluid concentrations of Ang II are in the nanomolar range. To avoid the confounding effects of decreases in mean arterial pressure (MAP), we administered the nonsurmountable AT1 receptor antagonist candesartan directly into the renal artery of nonclipped kidneys (n=10). The dose of candesartan (0.5 microg) did not significantly decrease MAP in 2K1C rats (152+/-3 versus 148+/-3 mm Hg), but effectively prevented the renal vasoconstriction elicited by an intra-arterial bolus of Ang II (2 ng). Candesartan elicited significant increases in glomerular filtration rate (GFR) (0.65+/-0. 06 to 0.83+/-0.11 mL. min-1. g-1) and renal blood flow (6.3+/-0.7 to 7.3+/-0.9 mL. min-1. g-1), and proportionately greater increases in absolute sodium excretion (0.23+/-0.07 to 1.13+/-0.34 micromol. min-1. g-1) and fractional sodium excretion (0.38+/-0.1% to 1.22+/-0. 35%) in 2K1C hypertensive rats. These results show that proximal tubular fluid concentrations of Ang II are in the nanomolar range and are much higher than can be explained on the basis of plasma levels. Further, the data show that the intratubular levels of Ang II in the nonclipped kidneys of 2K1C rats remain at levels found in kidneys with normal renin content and could be exerting effects to suppress renal hemodynamic and glomerular function and to enhance tubular reabsorption rate.     

The use and abuse of routine stool microbiology: a College of American Pathologists Q-probes study of 601 institutions

BACKGROUND/AIMS: In the present study we have evaluated the role of nitric oxide and prostaglandins in the renal vascular response to a vasoconstrictor (methoxamine) and to endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) vasodilators. METHODS: The experiments were performed in isolated and perfused kidneys of portal vein ligated and sham rats under various treatments. RESULTS: Baseline renal perfusion pressure was lower in the portal vein ligated than in the sham group (37.2 +/- 2.6 vs 48.4 +/- 2.5 mmHg). Indomethacin (10(-5)M) did not modify baseline renal perfusion pressure in any group, but the nitric oxide inhibitor N(W)-Nitro-L-Arginine (10(-4) M) increased it in both sham and portal vein ligated kidneys, but without abolishing the differences between them. The vasoconstrictor renal response to methoxamine was blunted in portal vein ligated rats compared to controls. Indomethacin did not modify this renal hyporesponsiveness, but N(W)-Nitro-L-Arginine completely abolished it. In another set of experiments, both acetylcholine and nitroprusside caused dose-dependent vasodilation in kidneys, preconstricted with methoxamine, from sham and portal vein ligated rats, and there were no significant differences between them. N(W)-Nitro-L-Arginine reduced acetylcholine-induced vasodilation and did not modify the vasodilation evoked by nitroprusside. CONCLUSIONS: These results indicate that the renal vasculature of portal vein ligated rats shows a basal reduction in perfusion resistance that is not related to nitric oxide or prostaglandins. However, increased nitric oxide production interferes with the effects of the alfa-agonist methoxamine. This suggests that nitric oxide plays an important role in the modulation of the renal vascular responses to vasoconstrictors in portal hypertension.     

Strategies for the prevention of a successful biological warfare aerosol attack

We evaluated the usefulness of dynamic turbo FLASH MR imaging in the differential diagnosis of complications after renal transplantation in 17 patients (10 from living relatives and 7 from cadavers). Coronal turbo FLASH dynamic images were obtained every 5 sec for 5 min after an intravenous bolus injection of Gd-DTPA. Corticomedullary differentiation (CMD) on spin echo coronal T1-weighted images and MR renogram patterns of the renal cortex and medulla were obtained for quantitative analysis of the Gd-DTPA-enhanced dynamic turbo-FLASH images. The signal intensity ratio of the medulla to cortex after Gd-DTPA enhancement was compared among four groups: normal (n = 9), acute tubular necrosis (ATN) or cyclosporine A (CyA) tubulopathy (n = 6), acute rejection (AR) in the living related donor kidney (n = 4), and AR in the cadaveric kidney (n = 5). Although loss of CMD was seen in severe renal dysfunction in the transplanted kidneys, there was considerable overlap among the four groups. On dynamic study, there was significant differences in the signal intensity ratio of the medulla to cortex between normally functioning kidneys or ATN/CyA tubulopathy and AR (p < 0.01). In patients with severe renal dysfunction, the arterial cortical peak was indistinct. In conclusion, MR renograms obtained from dynamic turbo FLASH MR imaging played a significant role in evaluating dysfunction of the renal transplant.     

Chemokine receptor (CCR5) expression in human kidneys and in the HIV infected macaque

BACKGROUND: The chemokine receptor, CCR5, has been identified as an essential co-receptor with CD4, which permits entry of human immunodeficiency virus (HIV) into mammalian cells. This receptor may also mediate leukocyte and parenchymal responses to injury by virtue of its binding to locally released chemokines such as RANTES, MIP-1 alpha and MIP-1 beta during inflammation. The localization of CCR5 in human or primate kidney is unknown. In this study we sought to identify sites of CCR5 synthesis through localization of mRNA coding for this peptide. METHODS: CCR5 cDNA cloned into an expression vector was transcribed into a 1.1 Kb antisense riboprobe that was utilized for in situ hybridization (ISH) and Northern blotting studies. RESULTS: Northern analysis demonstrated positive hybridization for CCR5 mRNA in total RNA isolated from allograft nephrectomy tissue with features of severe transplant rejection as well as in kidney tissue with focal interstitial nephritis. No comparable hybridization signal was achieved with human kidney tissue uninvolved by disease. CCR5 mRNA was not identified in intrinsic renal cell types by ISH in normal human (N = 6), normal macaque kidney (N = 5), in kidneys from macaques with established infection by HIV-2 (N = 9), kidneys from macaques infected with HIV-1 (N = 4), nor in kidneys from SIV-infected macaques (N = 5). CCR5 was identified by ISH in human kidneys with features of interstitial nephritis (N = 3) and in rejected human allograft kidneys (N = 14). The expression of CCR5 was restricted to infiltrating mononuclear leukocytes at sites of chronic tubulointerstitial injury and at sites of vascular and interestitial rejection, respectively. CONCLUSIONS: Understanding the localization of CCR5 as well as other chemokine receptors may help us understand how specificity in leukocyte trafficking is achieved in renal inflammatory processes such as allograft rejection and interstitial nephritis. They provide additional evidence that chemokines may be critical mediators of leukocyte trafficking in renal allograft rejection. These findings may account in part for the difficulty in demonstrating HIV infection of renal cells in human HIV infection, since these cells appear to lack constitutive expression of an essential co-receptor needed for viral entry.     

Promoter analysis of the Drosophila genes encoding TFIIB and TATA box-binding protein

BACKGROUND: Endothelial cells are known to be an early target of preservation/reperfusion injury and acute rejection, whereas the extracellular matrix (ECM) may also play an equally important role in the sequelae of both events. METHODS: Syngeneic and allogeneic rat small bowel transplantations (SBTX) were performed after 6 hr of preservation. Animals were subsequently killed at defined time points for determination of ECM parameters within the graft and in plasma. RESULTS: Laminin levels were significantly increased 20 min after reperfusion (syngeneic SBTX: 357+/-65.9 ng/ml; allogeneic SBTX: 361+/-79.6 ng/ml; P< or =0.01). After syngeneic transplantation, laminin levels normalized by postoperative day (POD) 7, whereas there was a rejection-induced increase after allogeneic SBTX (POD 7: 179+/-60.1 ng/ml; POD 9: 333+/-13.6 ng/ml; P< or =0.01 vs. syngeneic SBTX). This increase was accompanied by an increase in tumor necrosis factor-alpha levels at POD 9. Hyaluronic acid levels were significantly elevated after 24 hr (syngeneic SBTX: 1086+/-176 microg/L; allogeneic SBTX: 918+/-108 microg/L; P< or =0.01). After syngeneic SBTX, hyaluronic acid levels normalized by POD 7, whereas persistently higher levels were observed after allogeneic SBTX. Immunohistochemistry confirmed early changes (20 min after reperfusion) at the ECM. Anti-laminin and anti-CD44 staining normalized at POD 5 after syngeneic SBTX. After allogeneic SBTX, rejection-specific changes were evident with anti-laminin staining commencing on POD 5 and progressing until POD 9. At similar time points, increased expression of fibronectin- and interferon-gamma-positive material was evident. CONCLUSIONS: The ECM can be considered to be an early target of preservation/reperfusion injury and acute rejection. Plasma parameters reliably reflected the changes observed within the graft. Laminin and hyaluronic acid levels may be used as indicators of initial graft function. Furthermore, the increase in laminin levels was an early indicator of acute rejection. Determination of these parameters may significantly improve monitoring after SBTX.     

The co-culture of dermal fibroblasts with human epidermal keratinocytes induces increased prostaglandin E2 production and cyclooxygenase 2 activity in fibroblasts

BACKGROUND: We recently demonstrated that inhibition of nitric oxide (NO) production ameliorated acute pulmonary allograft rejection. This study examined whether inducible NO synthase (iNOS) was expressed in the transplanted lung during acute rejection. METHODS: With a rat left lung transplant model, tissue from syngeneic (Fischer 344 to Fischer 344) and allogeneic (Brown Norway to Fischer 344) transplants were harvested on postoperative day 4 and analyzed for iNOS mRNA expression (ribonuclease protection assay), iNOS enzyme activity (conversion of L-[3H]-arginine to NO and L-[3H]-citrulline), and serum nitrite/nitrate levels. RESULTS: The iNOS mRNA was expressed in allograft lungs but was not detected in isografts or controls. The iNOS protein was present in allograft lungs, as demonstrated by high levels of L-[3H]-citrulline production compared with minimal iNOS enzyme activity in isograft and control lungs (10.1 +/- 2.4 vs 0.6 +/- 0.2 and 0.7 +/- 0.2 pmol L-[3H]-citrulline.mg-1.min-1, respectively; n = 6, p < 0.001). Allografts had significantly elevated systemic serum nitrite/nitrate levels compared with isografts and controls (38 +/- 6 vs 18 +/- 2 and 16 +/- 1 mumol/L, respectively; n = 6; p < 0.005). CONCLUSIONS: These results, together with our previous demonstration that iNOS inhibition ameliorated lung allograft rejection, suggest that (1) iNOS expression and increased NO production contributed to acute rejection of the transplanted lung, (2) iNOS inhibition may offer an alternative in management of acute lung allograft rejection, and (3) increased NO production, detected by the presence of iNOS mRNA or protein or noninvasively by measuring serum nitrite/nitrate levels, may serve as an early marker of acute allograft rejection.     

Upregulation of atrial natriuretic peptide gene expression in remnant kidney of rats with reduced renal mass

Atrial natriuretic peptide (ANP) is synthesized in the kidney but its physiologic significance there is unclear. To determine whether renal expression of the ANP gene is regulated, renal ANP mRNA expression was assessed in remnant kidneys after 5/6 nephrectomy in Munich-Wistar rats. In normal sodium intake groups, ANP mRNA expression in the remnant kidney was significantly increased by 5.0 +/- 0.8-fold (n = 7, mean +/- SEM) at 4 d when compared with sham-operated controls (n = 6, all sham-operated groups) (*P < 0.001 by Scheffe's test) and by 28.3 +/- 5.1-fold at 14 d. This latter response was markedly diminished to 7.6 +/- 2.1-fold (n = 7, versus sham) in rats maintained on a low sodium diet. At 4 d, on the other hand, no significant downregulation was observed with dietary sodium restriction. Because natriuretic peptides have previously been shown by us to play a major role in the adaptive responses of remnant nephrons to renal mass ablation, these data suggest that ANP of renal origin may contribute to the overall mechanism for enhancing sodium excretion in the face of declining nephron number.     

Effects of protease therapy in the remnant kidney model of progressive renal failure

This study investigated whether protease treatment ameliorates the progressive course of chronic failure in the rat model of subtotal nephrectomy. Fourteen male Wistar rats underwent 5/6 nephrectomy, and were randomized into a control group (C, n = 7) given 2 ml of 0.9% NaCl intraperitoneally (i.p.) daily, and a study group (P, n = 7) treated with 12 mg Phlogenzym (combination of trypsin, bromelain, and rutosid) in 2 ml saline i.p. daily. After 6 weeks treatment, the Phlogenzym group showed lower proteinuria (C: 19.6 +/- 9.1 vs. 10.2 +/- 6.2 mg/24 h, p < 0.05). Endogenous creatinine clearance was higher (C: 192.3 +/- 99.4, P: 300.5 +/- 47.9 microliters/min per 100 g, p < 0.05), while plasma creatinine was decreased (C: 106.7 +/- 33.9, P: 76.0 +/- 6.3 mumol/l, p < 0.01). Blood urea nitrogen levels did not change, although urea clearance tended to a higher level in the protease-treated rats. Decreased renal formation of cytokines was reflected by a lower urinary excretion ratio of transforming growth factor (TGF)-beta/ creatinine (C: 0.363 +/- 0.183, P: 0.232 +/- 0.085 ng TGF-beta/mg creatinine, p < 0.05). Renal morphology revealed less infiltration of mononuclear cells and an amelioration of interstitial fibrosis as expressed by the volume index of the cortical region (C: 17.17 +/- 1.43; P: 12.3 +/- 0.5%, p < 0.001). In addition, the activities of lysosomal proteinases (cathepsin B, L + B, and H), which are decreased in the remnant kidney model of chronic renal failure, were significantly higher in the enzyme-treated group both in isolated glomeruli and proximal tubules. The body and kidney weight tended to be lower, probably due to a catabolic action of the enzymes. In summary, we provide evidence that protease treatment may be beneficial in a nonimmune mediated renal disease. Phlogenzym ameliorated the course of chronic renal failure in the rat model of subtotal nephrectomy and retarded the development of tubulointerstitial fibrosis. Decreased cytokine formation in the remnant kidney is supposed to play a key role.     

Spontaneous renal cell tumors in Long-Evans Cinnamon rats

Neoplastic lesions of the kidneys in untreated Long-Evans Cinnamon (LEC) rats of 57-118 weeks old (85 males and 34 females) and male F344 rats of 64-93 weeks old (59 males) were examined histologically. The incidences of renal cell tumors in male and female LEC rats were 6/80 (8%) in weeks 57-65, 3/19 (16%) in weeks 66-75, 3/8 (38%) in weeks 76-105 and 7/12 (58%) in weeks 106-118. Of these tumors, 13 were microscopic adenomas and 7 were renal cell carcinomas. The copper content of the kidneys was about three times higher in LEC rats than in F344 rats (P < 0.001), but the iron content of the kidneys was similar in the two strains.