Characterization of alpha 2-adrenoceptors mediating contraction of dog saphenous vein: identity with the human alpha 2A subtype

1. In the dog saphenous vein alpha 1- and alpha 2-adrenoceptors mediate noradrenaline-induced contractions in vitro. In order to study the alpha 2-adrenoceptor in isolation, alpha 1-adrenoceptors were inactivated by treatment of tissues with the alkylating agent phenoxybenzamine (3.0 microM for 30 min) in the presence of rauwolscine (1 microM) to protect alpha 2-adrenoceptors. 2. Noradrenaline-induced contractions of tissues treated with phenoxybenzamine were antagonized competitively by the selective alpha 2-adrenoceptor antagonist rauwolscine, pKB = 8.63 +/- 0.07 (means +/- s.e. mean; n = 3), consistent with an interaction at alpha 2-adrenoceptors. 3. Noradrenaline was a full agonist at alpha 2-adrenoceptors in dog saphenous vein. By use of the method of partial receptor alkylation and analysis of concentration-effect curve data by direct, operational model fitting methods, the affinity (pKA) and efficacy (tau) were 5.74 +/- 0.07 and 7.50 +/- 1.05, respectively (n = 6). Nine other agonists which were examined each had affinities higher than noradrenaline, but with the exception of the imidazoline, A-54741 (5,6-dihydroxy-1,2,3,4-tetrahydro-1-naphthyl-imidazoline) had relatively lower efficacies. 4. To compare the alpha 2-adrenoceptor in dog saphenous vein to the human recombinant subtypes, the affinities of twenty-one compounds were estimated in functional studies in the dog saphenous vein and in radioligand binding studies for the human alpha 2A, alpha 2B and alpha 2C receptor subtypes expressed in Chinese hamster lung (CHL) cells. 5. Of twenty-one compounds examined in ligand binding studies, only nine had greater than ten fold selectivity for one human receptor subtype over either of the other two. These compounds were A-54741, oxymetazoline, guanfacine, guanabenz, prazosin, spiroxatrine, tolazoline, WB 4101 and idazoxan. In dog saphenous vein, their affinities (pKA and pKB for agonists and antagonists respectively) were: A-54741 (pKA = 8.03 +/- 0.05), oxymetazoline (pKA = 7.67 +/- 0.09), guanfacine (pKA = 6.79 +/- 0.03); guanabenz (pKA = 7.02 +/- 0.13); prazosin (pKB = 5.19 +/- 0.08), spiroxatrine (pKB = 6.59 +/- 0.04), tolazoline (pKB = 6.21 +/- 0.07), WB 4101 (pKB = 7.42 +/- 0.09) and idazoxan (pKB = 7.11 +/- 0.08). 6. Comparisons of affinity estimates for these nine compounds at the receptor in dog saphenous vein and at the human recombinant subtypes suggest that the vascular receptor is most similar to the h alpha 2A subtype; correlation coefficients (r) were 0.82 (h alpha 2A), 0.24 (h alpha 2B) and 0.04 (h alpha 2C).     

Expressed alpha 1-adrenoceptors in adult rat brown adipocytes are primarily of alpha 1A subtype

The load distribution between two internal spinal fixation devices depends, besides other factors, on their stiffness. The stiffness ranges were determined experimentally for the clamps of the AO internal fixator with lateral nut and with posterior nut as well as for the clamps of the SOCON fixator. The stiffness of eight devices each differed by a factor of 3.1 for the clamp with lateral nut, by a factor of 1.5 for the clamp with posterior nut, and by a factor of 1.4 for the clamp of the SOCON fixator. For the AO clamp with lateral nut, the influence of the nut-tightening torque on the stiffness was determined. Using instrumented internal spinal fixation devices mounted to plastic vertebrae and simulating a corpectomy, the load distribution between the implants was measured for different tightening torques. It could be shown that, for the AO internal fixator whose clamps have a lateral nut, a nut-tightening torque > 5 Nm has only a negligible influence on load-sharing between the implants. Tooth damage occurs when the teeth of the clamp body and clamping jaw of the clamp with lateral nut do not gear together exactly, which leads to changes in the clamping stiffness and load-sharing between the two implants.     

Choline+ is a low-affinity ligand for alpha 1-adrenoceptors

The effect of choline+, a commonly used Na+ substitute, on ligand binding to alpha 1-adrenoceptors was investigated. It was found that replacement of 25% of the Na+ in a Krebs-Ringer bicarbonate buffer with choline+ led to a 3-fold decrease in the apparent affinity of [3H]prazosin for its binding site (i.e. the alpha 1-receptor) in a membrane preparation from brown adipose tissue, while no decrease in the total number of binding sites was observed. Similar effects were seen in membrane preparations from liver and brain. In competition experiments, it was found that choline+ could inhibit [3H]prazosin binding; from the inhibition curve, an affinity (Ki) of 31 mM choline+ for the [3H]prazosin-binding site could be calculated. In fully choline(+)-substituted buffers, where the level of [3H]prazosin binding was substantially reduced, both phentolamine and norepinephrine could still compete with [3H]prazosin for its binding site, with virtually unaltered affinity; thus choline+ did not substantially affect the characteristics of those receptors to which it did not bind. Choline+ did not affect the binding characteristics of the beta 1/beta 2 radioligand [3H]CGP-12177; thus, the effect on alpha 1-receptors was not due to general, unspecific effects on the membrane preparations. It is concluded that choline+ possesses characteristics similar to those of a competitive ligand for the alpha 1-adrenoceptor; it has a low affinity but the competitive type of interaction of choline may nonetheless under experimental conditions interfere with agonist interaction with the alpha 1-receptor.     

Subtype-specific differences in subcellular localization and chlorethylclonidine inactivation of alpha1-adrenoceptors

Chlorethylclonidine (CEC) inactivation has been used as one criterion to subclassify the alpha1-adrenoceptors (AR); however, the extent of CEC inactivation can vary depending on the CEC treatment. By constructing the FLAG-tagged (N-terminus) and green fluorescent protein (GFP)-fused (C-terminus) alpha1-ARs, we have determined the relationship between CEC sensitivity and the cellular localization of alpha1-AR subtypes using COS-7 cells. In GFP-expressing cells, flow cytometry analysis with anti-FLAG N-terminus antibody detected strong fluorescent signals in most of alpha1B-AR-expressing cells, but low signals in alpha1A-AR-expressing cells. Further examination with confocal microscopy showed that fluorescent signals densely localized intra-cellularly in alpha1A-AR-expressing cells, while most of alpha1B-AR localized on the cell surface. Furthermore, radioligand binding studies with [125I]HEAT showed that CEC (10 microM) treatment of intact cells inactivated approximately 30-40% of alpha1A-AR and >90% of alpha1B-AR, while the CEC treatment of membrane preparations resulted in >80% decrease in the alpha1A-AR density and >90% of alpha1B-AR density, respectively. The results showed that the hydrophilic alkylating agent CEC inactivated only alpha1-AR on the cell surface irrespective of its subtype, and that the subtype-specific sorting is a major determinant for CEC inactivation of alpha1-AR. Subtype-specific cellular localization suggests a new class of functional properties that may explain the signal and functional diversity of homologous alpha1-AR (as well as other G protein-coupled receptors) subtypes.     

Evidence for direct interaction of ketamine with alpha 1- and beta 2-adrenoceptors

1. Ketamine has a number of effects that suggest that it may interact with alpha- and beta-adrenoceptors. To date, the experimental evidence for this has been indirect and has been based on physiological studies using competitive blocking agents. In the present study we sought to determine from receptor binding studies whether ketamine binds directly to alpha- and beta-adrenoceptors. 2. Membrane preparations of alpha 1- and beta 2-adrenergic binding sites were obtained from urinary bladder and urethrae of sheep. These binding sites were characterized by saturation analyses using [3H]-prazosin for alpha 1-adrenoceptor binding sites and [125I]-cyanopindolol (CYP) for the beta 2-adrenoceptor binding sites. The receptors were further characterized by displacement studies using selective and non-selective antagonists. 3. Studies in which ketamine was used to displace [3H]-prazosin revealed a Kd of 3.40 +/- 1.23 x 10(-3) mol/L for ketamine binding to alpha 1-adrenoceptors. Displacement studies of [125I]-CYP by ketamine showed a Kd of 0.35 +/- 0.03 x 10(-3) mol/L for ketamine binding to beta 2-adrenoceptors. 4. We conclude that ketamine interacts directly with both alpha 1- and beta 2-adrenoceptors and that such interactions probably explain the reported effects of this agent on the vasculature and the bronchial tree.     

Serotonin-induced vasoconstriction in rabbit femoral artery: mediation by both 5-HT2 serotonergic and alpha 1-adrenoceptors

We determined the receptors mediating the contractile response of the rabbit femoral artery to serotonin in isolated vascular rings mounted in tissue baths for the measurement of isometric contraction. Serotonin elicited a biphasic concentration-response curve (CRC). The threshold and maximal concentrations of the first phase were 0.03 and 3 microM, respectively. The respective values for the second phase were 10 and 1,000 microM. Benextramine, a selective, irreversible alpha-adrenoceptor antagonist, eliminated the second phase. Similar results were obtained with benextramine in femoral arteries acutely denervated with 6-hydroxydopamine (6-OHDA). In contrast, the reversible, competitive 5-HT2 antagonist ketanserin shifted the first phase of the serotonin CRC to the right ina concentration-dependent manner but had little or no effect on the second phase. No evidence for functional alpha 2-adrenoceptors was found. We conclude that the first phase of the serotonin CRC in rabbit femoral artery was mediated predominantly by 5-HT2 receptors and that the second phase was mediated by alpha 1-adrenoceptors.     

Distribution and pharmacology of alpha 2-adrenoceptors in the central nervous system

Three subtypes of the alpha 2-adrenoceptor have been characterized. The drugs currently available which most specifically activate (e.g. dexmedetomidine) or antagonize alpha 2-receptors (e.g. atipamezole, idazoxan) do not show significant differences in their affinities for the subtypes. The drugs which do show some subtype selectivity (oxymetazoline for alpha 2A; prazosin for alpha 2B and alpha 2C) are not useful for in vivo pharmacology due to their relative nonspecificity in binding to other receptors (e.g. alpha 1-adrenoceptors). By examining the distribution of the mRNA coding for the three subtypes, it has been possible to map those regions in the brain which possess cells which synthetize the distinct subtypes. The mRNA coding for alpha 2A receptors is found throughout the brain, especially in locus coeruleus, a region which contains the cell bodies for the ascending and descending noradrenergic neurones. The mRNA for alpha 2B receptors was only found in thalamus. The alpha 2C mRNA had a wider distribution, in basal ganglia its expression was particularly intense. One must hope that the fact that the receptor subtypes are not uniformly distributed throughout the brain means that new subtype selective drugs will not suffer from the same broad diversity of actions of the present alpha 2-agonists and antagonists.     

Evaluation of histological structure and its effect on the distribution of alpha1-adrenoceptors in human benign prostatic hyperplasia

Oncogene-bearing transgenic mice develop various kinds of tumors depending on both the regulatory sequences and the specific oncogene used. These mice not only help to clarify the pathogenetic pathways leading to tumor formation, but can also be useful as models to test novel therapeutic strategies, including gene therapy. We have previously reported the establishment of an MMTV-neu (ErbB-2) transgenic mouse lineage, in which 100% of females develop breast tumors with many features similar to their human counterparts; these tumors are due to the over-expression of the activated rat neu oncogene in the mammary gland. From one such mouse we established a cell line of mammary adenocarcinoma named MG1361. We report here that the growth of this cell line can be inhibited in vitro and in vivo by transfection of a plasmid vector carrying an antisense anti-neu construct. This inhibitory effect is specific, as it is related to the expression of the antisense transgene (determined by RT-PCR), and to a reduction in neu mRNA and protein, as determined by Northern and Western blot analyses. Moreover, inoculation of cells carrying the antisense or the control vector in nude mice demonstrated that the morphological and biochemical effects elicited by the antisense construct resulted in a significantly slower rate of in vivo growth of tumor xenografts. Finally, significant mammary tumor growth inhibition was obtained after liposome-mediated direct inoculation of the same antisense vector in tumors spontaneously arising in MMTV-neu mice. Taken together, these findings suggest that targeting neu expression by an integrated large anti-neu antisense segment affects the in vivo growth of these tumors.     

The regulation of mitogenesis and apoptosis in response to the persistent stimulation of alpha1-adrenoceptors: a possible role of 15-lipoxygenase

1. Activation of alpha1-adrenoceptor stimulation regulates eicosanoid metabolism and growth in vascular smooth muscle cells (VSMCs). The purpose of this study was to investigate the functional implications of lipoxygenase pathway in alpha1-adrenoceptor-stimulated VSMCs growth through mutually exclusive biological functions, that is cell proliferation and cell death. 2. Phenylephrine (10 microM), a specific alpha1-adrenoceptor agonist, enhanced [3H]-thymidine incorporation by 300% above basal. Nordihydroguaiaretic acid (NDGA), a lipoxygenase inhibitor, caused 36 and 50% decrease in phenylephrine (10 microM)-stimulated [3H]-thymidine incorporation at concentrations of 1 microM and 10 microM respectively. 3. Inversely, treatment of phenylephrine (10 microM)-stimulated VSMCs with NDGA induced DNA fragmentation in a dose-dependent fashion. The level of induction of DNA fragmentation by NDGA was 225, 319 and 406% above the phenylephrine (10 microM)-level at concentrations of 0.1 microM, 1 microM and 10 microM, respectively. This induction of DNA fragmentation was partially prevented by exogenous 15-hydroxyeicosatetraenoic acid (15-HETE). The inhibition of apoptosis was 53 and 63% at concentrations of 5 microM and 10 microM of 15HETE, respectively, as compared with phenylephrine (10 microM) in the presence of NDGA (10 microM). 4. Furthermore, we performed the time-course analysis of Bcl-2 protein expression in phenylephrine (10 microM)-stimulated VSMCs. The expression of Bcl-2 protein disappeared after a 2 h incubation in the presence of NDGA (10 microM), but remained stable after a 2 h incubation period in the absence of NDGA (10 microM). 5, These results suggest that the lipoxygenase pathway is involved in cell proliferation by preventing apoptosis through the level of Bcl-2 protein expression.     

Norepinephrine inhibits neurons of the intermediate subnucleus of the lateral septum via alpha2-adrenoceptors

The physiological and pharmacological actions of norepinephrine (NE) on neurons of the intermediate subnucleus of the lateral septum (LSI) were examined using intracellular recordings in rat brain-slices. Bath-applied NE inhibited 72.5%, excited 5.5% and had no effect on 22% of LSI neurons tested; this study focused on the inhibitory effects of NE. In current clamp recordings, 100 microM NE produced a hyperpolarization of 10.82+/-0.72 mV (n=84) with a decrease in input resistance. In voltage-clamp, NE produced a direct, post-synaptic outward current of 206.8+/-22 pA (n=37) with a 64. 3+/-4.9% increase in input conductance (IC50-17.7+/-4 microM). The NE-induced inhibition was mimicked by the alpha2-agonist, UK14,304, but not by the alpha1- or beta-adrenoceptor agonists. The alpha2-agonist, clonidine, had a weak effect in LSI neurons. Interestingly, the magnitude of the UK14,304-induced response varied between cells (ranging from 29.5 to 320% of the maximal NE inhibition), possibly suggesting the involvement of alpha2A-(high affinity for UK14,304) and non-alpha2A (low affinity for UK14,304) adrenoceptor subtypes. While the alpha2-antagonists, yohimbine, rauwolscine and idazoxan blocked NE-induced inhibition in all neurons tested, the prototypical alpha1-antagonist, prazosin produced a variable degree of block (9-58%), further indicating the possible involvement of alpha2A (prazosin-insensitive) and non-alpha2A (prazosin-sensitive) receptors. However a lack of more selective pharmacological tools precludes definitive classification of the alpha2-receptor-mediated responses into different subtypes. The alpha2-receptor-mediated current in LSI neurons displayed Ba2+-sensitive inward rectification, reversed polarity near EK and was sensitive to external K+. In conclusion, NE inhibits LSI neurons via alpha2-adrenoceptor subtypes.     

The expression of functional postsynaptic alpha2-adrenoceptors in the corpus cavernosum smooth muscle

1. The purpose of this study was to determine if corpus cavernosum smooth muscle expresses functional postsynaptic alpha2-adrenoceptors (AR). 2. The alpha2-adrenoceptor agonist UK 14,304 elicited concentration-dependent contractions in rabbit corpus cavernosum smooth muscle (CCSM). The half-maximal response occurred at 0.32+/-0.03 microM and the maximum contraction at 10 microM UK 14,304. 3. Pretreatment of CCSM strips with selective alpha2-adrenoceptor antagonists, rauwolscine and RS-15385, produced rightward shifts in the dose-response curves to UK 14,304 (pA2 values 7.1 and 8.5, respectively). In contrast, these antagonists did not alter contraction induced by the alpha1-adrenoceptor agonist phenylephrine (PE) or oxymetazoline. UK 14,304-induced contractions were also inhibited by prazosin (pA2 = 9.08). 4. UK 14,304-induced contractions, unlike those to PE, were highly dependent on the presence of extracellular Ca2+. 5. [3H]-rauwolscine bound to CCSM membranes with high affinity (Kd = 1.5 nM). [3H]-rauwolscine binding was displaced by unlabelled rauwolscine, RS-15385, UK 14,304 and prazosin, but not by PE. 6. UK 14,304 inhibited forskolin and prostaglandin E1 (PGE1)-induced increases in intracellular cyclic AMP concentration in primary cultures of rabbit CCSM cells. 7. These results demonstrate that CCSM expresses Gi-coupled postsynaptic alpha2-adrenoceptors, and activation of these receptors causes contraction of trabecular smooth muscle.     

Prejunctional alpha2-adrenoceptors and peroxide-induced potentiation of norepinephrine release from the bovine iris

Peroxides can enhance field-stimulated [3H]norepinephrine ([3H]NE) release in isolated irides from several mammalian species. In the present study, we investigated the role of prejunctional alpha2-adrenoceptors in peroxide-induced potentiation of sympathetic neurotransmission in bovine isolated irides. Isolated hemi-irides were incubated in a Krebs buffered-solution containing [3H]NE and prepared for studies of neurotransmitter release using the superfusion method. Alpha2-adrenoceptor agonists, oxymetazoline, UK-14304 and clonidine inhibited field-stimulated [3H]NE overflow without affecting basal tritium efflux. Pretreatment of tissues with H2O2 (300 microM) had no effect on inhibition of evoked [3H]NE release caused by the alpha2-adrenergic agonists. However, H2O2 (300 microM) caused significant (P < 0.01) leftward shifts of excitatory concentration-response curves to yohimbine (10 nM-1 microM). In contrast, yohimbine (1 microM) did not prevent the enhancement of evoked [3H]NE overflow induced by H2O2 (300 microM). In conclusion, excitatory effects of peroxides on sympathetic neurotransmission in bovine irides are not mediated by prejunctional alpha2-adrenoceptors.     

The clinical significance of type 1 fiber predominance

Having recently demonstrated that taurine supplementation prevents total parenteral nutrition (TPN)-induced cholestasis, we chose to use this model to examine plasma membrane composition in relation to bile formation. Male guinea pigs received daily a mixture of glucose and of the amino acid solution Travasol with or without added taurine (1.2 mM). After 3 days, bile was collected and liver plasma membrane fractions enriched in sinusoidal lateral membrane and bile canalicular membrane domains were isolated. In animals receiving TPN alone, bile flow and biliary secretory rate of bile acid and bicarbonate decreased significantly compared with controls. Although membrane ATPases (Na+K+ and Mg+) were unchanged, TPN induced an increase in the lipid to protein ratio and a decrease of polyunsaturated fatty acids, in conjunction with a higher content of diene conjugates in sinusoidal lateral membrane fractions. Taurine corrected these changes and, in addition, reduced significantly the cholesterol to phospholipid ratio in both membrane fractions. The data show that changes in liver cell membranes occur in TPN-induced cholestasis and suggest that free radical injury may play a role. As taurine prevented cholestasis as well as membrane changes, it is suggested that taurine should be added to amino acid solutions used for parenteral nutrition.     

Platelet alpha 2-adrenoceptors and diurnal changes of platelet aggregability in hypertensive patients

OBJECTIVE: To analyse whether platelets from hypertensive patients have an increased responsiveness to aggregating agents during morning hours and whether these changes might be related to concurrent changes in platelet membrane alpha 2-adrenoceptor characteristics, plasma catecholamine and cortisol levels, and blood pressure values. DESIGN AND METHODS: Blood samples from 14 mild-to-moderate essential hypertensive males were collected in the morning (0700-0900 h) and the evening (1900-2100 h) to determine platelet aggregability responses to adrenaline and ADP, platelet alpha 2-adrenoceptor number and binding affinity to [3H]-yohimbine, plasma catecholamines and cortisol. During the same day patients underwent 24-h ambulatory blood pressure monitoring. RESULTS: The lowest concentration of adrenaline required to induce biphasic aggregation was significantly lower in the morning than in the evening, indicating an increased morning platelet aggregability to adrenaline; the minimum ADP concentration inducing aggregation was similar in morning and evening samples. There were no significant differences between morning and evening samples in platelet alpha 2-adrenoceptor number and binding affinity. Plasma adrenaline, noradrenaline and cortisol levels were higher in the morning than in the evening, but no correlation was observed between hormonal changes and the morning increase in platelet sensitivity to adrenaline. Ambulatory blood pressure recording showed abrupt morning elevations in systolic and diastolic blood pressures over sleeping values. However, morning blood pressure readings were not significantly different from those recorded during the rest of the day and in the evening. The morning rise in mean arterial pressure displayed a significant inverse correlation with the increased platelet sensitivity to adrenaline that was observed during the same hours. CONCLUSIONS: The results indicate that the increased morning responsiveness to adrenaline that was observed in platelets obtained from hypertensive patients does not appear to be mediated by changes in the characteristics of platelet membrane alpha 2-adrenoceptors, but morning blood pressure elevations might play some role in inducing this platelet hyper-reactivity.     

Naturally occurring clavines: antagonism/partial agonism at 5-HT2A receptors and antagonism at alpha 1-adrenoceptors in blood vessels

A study was made of 12 patients with head and neck cancer who underwent surgical neck dissection in 1993 to evaluate quantitatively the degree of postoperative shoulder dysfunction after surgical neck dissection. Nerve conduction studies were made of the accessory nerve and the range of motion, strength and position of the shoulder were evaluated. Patients were invited to complete a questionnaire about daily living activities, shoulder pain, shoulder movement and shoulder droop. Our results showed that abnormalities can be found in shoulder and arm function after any type of neck dissection and that these are evident when the accessory nerve is damaged. Subjective questionnaire findings generally coincided with objective postoperative dysfunction.     

Activation of alpha 1-adrenoceptors to lower cerebrocortical neuropeptide Y (NPY)-like immunoreactivity in rats receiving pargyline treatment

To determine if inhibition of a Ca(2+)-dependent slow afterhyperpolarization (AHPslow) contributes to prostaglandin E2 (PGE2)-induced sensitization of DRG neurons, we have used patch-clamp electrophysiological techniques on cultured dorsal root ganglion (DRG) neurons from the adult rat. In support of a role for AHPslow in sensitization of DRG neurons, we demonstrate that: (1) AHPslow expression is restricted to a subpopulation of putative nociceptors; (2) burst duration is controlled by AHPslow in these neurons; and (3) in some neurons, PGE2 decreases AHPslow and produces a concomitant increase in the number of action potentials generated in response to depolarizing current injection. However, our results also demonstrate that AHPslow modulation is not sufficient to explain PGE2-induced sensitization in the majority of DRG neurons because: (1) the size of the population of DRG neurons expressing AHPslow is less than half the size of the population of DRG neurons sensitized by PGE2; (2) PGE2 produces a decrease in action potential threshold as well as an increase in the number of action potentials in response to current injection, while inhibition of AHPslow has little effect on threshold; and (3) the sensitizing effects of PGE2 are dissociated from its effects on AHPslow in more than half of neurons tested. We conclude that PGE2-induced sensitization must involve the modulation of ionic currents in addition to that underlying AHPslow.     

Characterization of cytochrome P450 (CYP3A12) induction by rifampicin in dog liver

We investigated the mechanisms of renal vascular wall thickening in a rat model of N-nitro L-arginine methyl ester (L-NAME)-induced hypertension. To separate the effects of L-NAME-induced hypertension from other effects of nitric oxide (NO) inhibition, we created two models of L-NAME-induced hypertension: both had the same blood pressure level but NO inhibition was moderate in one group (group M) and severe in the other (group S). Urinary excretion of nitrates and nitrites was lower in group S than in group M. Wall thickening and lipid deposition in renal vessels were significantly greater in group S than in groups M. Simple and multiple regression analyses indicated that renal vascular wall thickening was more strongly correlated with lipid deposition than with blood pressure. The number of vessels positive for staining with Sudan black B was negatively correlated with urinary NO excretion. Expression of fibronectin and transforming growth factor-beta was greater in the Sudan black B-positive than in the Sudan black B-negative vessels, suggesting that extracellular matrix production was increased in vessels with lipid deposition. Lipid deposition and increased production of extracellular matrix may contribute to renal vascular wall thickening in L-NAME-induced hypertension. Some mechanisms independent of hypertension play important roles in vascular wall thickening induced by NO inhibition.     

Transplantation for end stage liver disease related to alpha 1 antitrypsin

Alpha 1 antitrypsin deficiency (AT) is an autosomal recessive disease associated with chronic liver disease in adults and children and emphysema in adults. The disease is one of the most common inherited disorders of the Caucasian population of North Europe and North America and is the most common genetic reason for pediatric orthotopic liver transplantation (OLTx), although it is a rare indication in adults. The natural history of the disease is unpredictable and the pathogenesis of the liver injury unclear. Thirty-five patients with histologically apparent alpha 1 AT accumulation in the liver (22 adults, 13 children) have been transplanted in this center. Clinical features were correlated with the pretransplant phenotype, serum alpha 1 antitrypsin levels and potential precipitating factors. All children were PiZZ homozygotes, most of whom had presented with neonatal hepatitis. The majority of adult patients were heterozygotes presenting with portal hypertension and liver cirrhosis. Current one-year posttransplant survival figures are 73% for adults and 87.5% for children. Replacement of the cirrhotic liver results in acquisition of the donor phenotype, a rise in serum levels of alpha 1 antitrypsin, and apparent prevention of associated disease.