Effects of total fasting or chronic food restriction on plasma endothelin levels in rats

We tested the effects of 24- and 48-h fasting and 40% calorie restriction stresses on plasma endothelin (ET)-1,2 levels in male Sprague-Dawley rats. Plasma ET-1,2 levels in pg/ml were lower in 24-h fasted rats (15.48 +/- 3.49), 48-h fasted rats (5.28 +/- 4.32), and in chronically food-deprived rats (R) (10.49 +/- 6.28) compared to ad lib-fed (AL) rats (21.23 +/- 9.38). The R rats were pair-fed 40% fewer calories than AL rats. We conclude that calorie restriction or total food deprivation stress decreases plasma ET-1,2 levels, unlike many other forms of physiological stress that have been shown to increase plasma ET-1,2 levels.     

Acute effects of histamine on plasma prolactin and luteininzing hormone levels in male rats

Histamine injected into the 3rd ventricle of normal male rats at doses of 5-60 mug (free base) caused a marked release of prolactin. Responses were prevented by the antihistamine chlorpheniramine but not by atropine, methysergide or phenoxybenzamine. It thus seems that effects of histamine on prolactin are specific and not mediated by other neurotransmitters. Plasma LH remained normal after injection of low doses but it was decreased after high doses. The results obtained indicate a facilitatory role of histamine on prolactin release.     

The plasma levels of endothelin in diabetic retinopathy and their changes after treatment with doxium

Apolipoprotein E (APOE) has been identified as a major susceptibility marker for Alzheimer's disease (AD) and it has been proposed that a common polymorphism in the alpha1-antichymotrypsin (ACT) gene increases the risk of developing AD, when the combination of ACT/AA genotype and APOE epsilon4 allele segregate together. The ACT polymorphism was analysed in 218 sporadic late-onset AD patients and 101 healthy control subjects from Eastern Finland. Samples of the ACT polymorphism were divided into three subgroups according to their APOE genotypes and the genotyping of samples was done using the polymerase chain reaction (PCR) method. Any association between the AD group and the controls was tested with the chi2 test. Our data failed to detect any effect of polymorphism in the ACT genotypes associated with the APOE alleles, suggesting that in this population ACT does not increase the risk of AD.     

Clinical significance of plasma endothelin levels in patients with biliary atresia

Biliary atresia (BA) is the end-result of a destructive inflammatory process that affects intra- and extrahepatic bile ducts, leading to fibrosis and obliteration of the biliary tracts with the development of biliary cirrhosis and portal hypertension (PH). Endothelins (ET) are 21-amino-acid peptides of endothelial origin with potent vasoconstrictor activity that bind to various cells of the liver. Nothing is presently known about plasma ET levels in BA. The aim of this study was to determine the clinical significance of plasma ET levels in patients with BA after hepatic portoenterostomy (Kasai's procedure) and to correlate these with liver function tests (LFT) and PH. We measured plasma concentrations of ET in 19 patients with BA (5 boys and 14 girls; mean age 11.6 +/- 5.5 years) after portoenterostomy and 10 age-matched controls. Patients were grouped according to outcome based on LFT: group A consisted of 9 patients with an "unfavorable outcome" and Group B 10 patients with a "favorable outcome". The plasma ET levels were measured using a highly sensitive and specific enzyme immunometeric assay (EIA). No patient had ascites or hepatorenal syndrome. Plasma ET levels were significantly higher in patients with BA than in controls (3.42 +/- 0.42 vs 1.75 +/- 0.39 pg/ml, respectively; P < 0.01) and in patients in group A than in group B. (3.75 +/- 0.25 vs 3.06 +/- 0.23 pg/ml, respectively; P < 0.01). In group A, plasma ET levels were higher in patients with PH (n = 4) than in those without PH (n = 5) (3.99 +/- 0.06 vs 3.64 +/- 0.22 pg/ml, respectively; P < 0.05). We conclude that plasma ET levels are high in patients with BA, especially those with severe biliary cirrhosis, and that ET may partially contribute to development of PH in BA. The results of the present study also suggest that plasma ET concentrations may be a useful marker in the follow-up of patients with BA.     

The effect of sulphamethoxypyridazine on liver and plasma levels of vitamin A in rats

1 Long-acting sulphonamides are highly bound to plasma proteins; the present study deals with the effects of this binding property upon a vitamin A compound also transported by plasma proteins. 2 Sulphamethoxypyridazine was administered in rats either orally or by intraperitoneal injection. 3 A significant fall in plasma vitamin A level and an increase in hepatic vitamin A concentration were observed. 4 These results suggest an interference by sulphamethoxypyridazine with the transport of vitamin A, either through competition between the drug and vitamin A for binding sites of plasma proteins, or through altered secretion of the vitamin from the liver.     

The role of splenic macrophages in plasma tumor necrosis factor levels in endotoxemia

We investigated the function of splenic macrophages (M phi s) with respect to changes in plasma tumor necrosis factor (TNF) in lethally endotoxemic rats treated with gadolinium chloride (GdCl3), which blocks the phagocytosis of large liver M phi s. We also carried out an immunohistochemical study to investigate the change of populations of liver and splenic M phi s under the condition of dysfunction of liver M phi s with or without splenectomy. Twenty-four-hour survival rates were 100% in the GdCl3-treated group (n = 6) and 0% in the nontreated group (n = 6). These rates did not change with splenectomy. Immunohistochemical examination with the primary monoclonal antibodies ED1, ED2 and ED3 revealed that large liver M phi s were eliminated after GdCl3 injection, and that this was not related to splenectomy. The splenic M phi s were not affected by GdCl3 treatment. Plasma TNF levels did not differ between the GdCl3-treated and the nontreated groups, irrespective of whether splenectomy was performed. It was suggested that plasma TNF levels are not affected by the splenic M phi s and that they do not compensate for dysfunction of liver M phi s after GdCl3 treatment.     

Renal and vascular effects of chronic endothelin receptor antagonism in malignant hypertensive rats

The effect of the combined ETA/ETB endothelin receptor antagonist bosentan on blood pressure, vascular hypertrophy, and pathologic renal changes was investigated in a model of malignant hypertension, severe vascular hypertrophy, and enhanced vascular expression of endothelin-1, the deoxycorticosterone acetate (DOCA), and salt-treated spontaneously hypertensive rat (SHR). DOCA-salt treated SHR received 100 mg bosentan per kilogram weight per day mixed with their food. Systolic blood pressure of untreated DOCA-salt SHR rose to 241 +/- 1.5 mm Hg, whereas that of bosentan-treated rats rose to 221 +/- 5.1 mm Hg (P < .01). Cardiac and conduit artery mass were not affected by treatment. Small arteries from the coronary, renal, and mesenteric circulations showed a smaller media width and cross-sectional area of the media in rats treated with bosentan than in untreated rats. The kidneys showed the presence of fibrinoid necrosis in a high percentage of afferent arterioles and glomeruli of untreated DOCA-SHR. Some kidneys of treated rats exhibited less severe vascular hypertrophy and lesser extent of vascular or glomerular fibrinoid necrosis, but the renal injury score of bosentan-treated DOCA-SHR was only at the limit of significance from that of untreated rats (P = .06). These results suggest a role for endothelin-1 in blood pressure elevation and the severe vascular hypertrophy of small arteries of the coronary, renal, and mesenteric vasculature, but not of the heart or larger conduit vessels in the malignant hypertension that SHR develop after treatment with DOCA and salt. Although some bosentan-treated rats showed fewer renal lesions, a significant effect on renal pathology could not be unambiguously demonstrated. Further studies will be necessary to determine whether endothelin antagonists may indeed offer some degree of renal protection and have therapeutic potential in severe or malignant hypertension.     

Interrelationship of cardiovascular effects, plasma levels of nicorandil, and vascular cGMP formation in conscious rats

OBJECTIVE: To determine the reproducibility of duplex Doppler waveform analysis and fetal cardiac interventricular septal thickness measurement and to compare these parameters in matched pregnancies with and without well-controlled maternal Type 1 diabetes at 18-20 weeks of gestation. DESIGN: A prospective blind twin cohort study and a blinded inter-observer and intra-observer agreement study. SETTING: A tertiary referral prenatal diagnostic unit within a university hospital. RESULTS: Good inter- and intra-observer agreement was found for the measurement of transvalvular peak flow velocities and the duration of ventricular ejection in the fetal heart. Inter-observer agreement for aortic flow acceleration rate was poor. M-mode measurement of interventricular septal thickness showed moderate reproducibility. The mean (SD) width of the interventricular septum in the fetuses of well controlled diabetic women was 2 1 mm (0.2 mm), and was significantly greater (P=0.01) when compared with the corresponding value in matched controls [1.9 mm (0.2 mm)]. No cardiac functional differences were evident. CONCLUSIONS: On-screen video analysis of Doppler cardiac flow waveforms and M-mode measurement of intraventricular septal thickness demonstrated good reproducibility. The fetuses of well controlled diabetic pregnancies demonstrated signs of altered cardiac morphology early in pregnancy, before any evident alterations in cardiac function.     

The effects of selenium supplementation on antioxidative enzyme activities and plasma and erythrocyte selenium levels

Nucleotide pyrophosphatase (EC 3.6.1.9) is a membrane enzyme purified from a number of mammalian sources that may have alkaline phosphodiesterase I (EC 3.1.4.1) activity as well. The mol. wt and subunit structure of this membrane glycoprotein are similar to that of the murine plasma cell alloantigen, PC-1. The PC-1 protein is a disulfide-bonded dimer of identical 115 kDa polypeptides that is selectively expressed on B lineage cells that have reached the degree of maturation associated with immunoglobulin secretion. It also has restricted expression in certain non-lymphoid tissues. In this report, we show that alkaline phosphodiesterase I activity parallels PC-1 mRNA expression in a number of B lineage cell lines at different stages of differentiation. Furthermore, we demonstrate increases in both nucleotide pyrophosphatase and alkaline phosphodiesterase I enzymatic activities in transiently transfected COS-7 cells expressing a cloned PC-1 cDNA construction. These results extend our previous immunological and correlative studies and directly ascribe an enzymatic activity to this cell surface differentiation antigen. These experiments also demonstrate that a single protein is responsible for both alkaline phosphodiesterase I and nucleotide pyrophosphatase activities.     

Regulation of cholesterol levels in plasma and liver of adult rats

The dynamics of cholesterol-system in the plasma is characterized by a parameter which is a linear function of the internal secretion of cholesterol. So, the level of plasma cholesterol from synthesis is a low as its flow is high. Moreover, the level of plasma cholesterol from diet is simultaneously proportional to the flow of cholesterol intestinal absorption and dependent on the dynamics controlled by the internal secretion. The laws of the cholesterolemia cumulate these partial laws. Similar relations concern the esterified cholesterol in the liver.     

The effects of aging and calorie restriction on plasma nutrient levels in male and female Emory mice

We examined the effect of diet, age (4.5, 13 and 23 months), and sex on plasma levels of retinol, tocopherol, ascorbate, cholesterol, glucose and glycohemoglobin in male and female Emory mice which were fed control (C) and 50% calorie restricted (R) diets. Results showed that C fed animals tended to have higher levels of plasma ascorbate (50-71%), cholesterol (23-71%), glucose (38-81%) and glycohemoglobin (50%). However, these diet differences varied with the age and sex of the animals. Plasma retinol levels were lower only in R males vs. C males (50%). Novel sex-related differences in levels of plasma retinol (2-fold higher in C male mice than in C or R female mice) are described. Aging was associated with trends towards lower levels of plasma ascorbate (14-25%), glucose (34-36%) and glycohemoglobin (47-57%) from 4.5 to 23 months of age. However, these age differences depended upon the diet and sex of the animals. These data suggest that lower plasma levels of glucose, glycosylated hemoglobin and cholesterol may be causally related to the life extension noted in R animals since elevated levels of these moieties have been related to aging. Since oxidative stress is thought to be causally related to aging it appears unlikely that retinol, tocopherol and ascorbate are causally related to R-induced life-extension.     

Effect of hepatic vagotomy on plasma insulin levels during fasting in rats

The present investigation was designed to evaluate the effect of a selective hepatic vagotomy (HV) on the insulin response in rats fasted for 24 h when blood glucose levels were or were not maintained by a constant glucose infusion. Rats were divided into three dietary groups: one group of normally fed rats, one group of 24-h fasted rats, and one group of 24-h fasted rats infused with glucose throughout the fasting period. Each of these groups was subdivided into HV and sham-operated (SHM) rats. Fasting without glucose infusion resulted in a significant (p < 0.05) decrease in plasma glucose, liver glycogen, and insulin concentrations and in a significant (p < 0.01) increase in beta-hydroxybutyrate and FFA concentration. Despite the maintenance of plasma glucose concentrations in the glucose-infused groups, the concentrations of liver glycogen and insulin were still decreased (p < 0.01) and the concentrations of beta-hydroxybutyrate were still increased (p<0.05) at the end of the fasting period. However, no significant differences in insulin or in beta-hydroxybutyrate concentration were found between HV and SHM rats. It is concluded that the decline in plasma glucose concentration during fasting does not totally explain the insulinopenic response to fasting, and that the liver, through the mediation of the hepatic vagus nerve, does not seem to contribute to insulinopenia in 24-h fasted rats.     

The effects of propranolol, practolol and metoprolol on exercise-induced tachycardia in relation to plasma levels in man

1. The effects of single oral doses of propranolol, practolol and a new cardioselective beta-adrenoceptor blocking drug, metoprolol, on exercise-induced tachycardia in relation to plasma levels were studied in six normal volunteers. 2. Exercise undertaken on treadmill was submaximal which, under control conditions, increased the heart rate from 74-3 (s.e.m. = 6-8) to 153-8 (s.e.m. = 9.8) beats/min. 3. Plasma concentrations of propranolol and practolol were assayed fluorometrically and of metoprolol by electron-capture gas liquid chromatography, the details of which are described. 4. Between 1-5 and 2 h after drug ingestion 80 mg of propranolol associated with plasma level of 50-60 ng/ml (half-life 2-75 h), reduced the exercise-induced tachycardia by 27%, 250 mg of practolol with plasma levels of 1050-1100 ng/ml reduced it by 28% and 100 mg of metoprolol with plasma concentrations of 140-150 ng/ml (half-life 1-7 h), reduced it by 30%. 5. The resting heart rates were reduced significantly by propranolol and metoprolol but not by practolol. 6. Metoprolol is a potent short-acting beta-adrenoceptor antagonist; its advantages as a cardioselective agent over practolol in therapeutic use are discussed.     

The effects of spaceflight on mRNA levels for cytokines in proximal tibia of ovariectomized rats

BACKGROUND: Bone resorption was elevated in ovariectomized rats during a 14-d orbital spaceflight over and above that caused by gonadal hormone deficiency. Locally produced cytokines are believed to have an important role in normal as well as abnormal bone resorption. METHODS: The purpose of the present study in the same rats was to determine whether spaceflight results in altered expression of cytokines in cancellous bone. The mRNA levels for selected cytokines were determined in proximal tibial metaphysis using ribonuclease (RNase) protection assays. RESULTS: The message for interleukin 1 receptor antagonist, interleukins 1alpha, 10, and 12, macrophage migration inhibitory factor, and tumor necrosis factor-alpha was below the limit of detection for all groups. Interleukin 6 and transforming growth factor-beta2 were expressed in bone but the mRNA levels for these cytokines were not altered by either ovariectomy or spaceflight. There was a tendency for interleukin-1beta message to be increased following ovariectomy (OVX) and this tendency achieved statistical significance following spaceflight. Finally, spaceflight resulted in an increase in the message level for interferon gamma in OVX rats. In summary, spaceflight results in increases in mRNA levels of two cytokines in OVX rats which have been shown to increase bone resorption.     

Behavior of plasma levels of endothelin 1 and noradrenaline in patients with stable angina during the cold pressor test

The aim of this study was to evaluate the behaviour of plasma endothelin-1 (ET-1) and norepinephrine (NE) levels in patients with stable angina during a sympathetic stimulation test as the cold pressor test. We enrolled in the study 29 subjects: 14 patients with stable angina (all men, mean age 58.3 +/- 7.3 years) and 15 healthy subjects (all men, mean age 54 +/- 5 years). All patients with stable angina had a stenosis of the coronary arteries (at least 70% of the stenosis in one of the coronary arteries) confirmed by angiography. Before (-15 min; 0 min) during (+2 min) and after the cold pressor test (+5 min, +10 min, +20 min, +30 min) were measured the blood pressure and the heart rate. At the same time were collected venous samples for the ET-1 and NE determination. ET-1 levels increased only in the patients with stable angina (ET-1: O' = 9.8 +/- 3.7 pg/ml; +2' = 11.1 +/- 4.5 pg/ml; +10' = 14.8 +/- 7.1 pg/ml; +20' = 11.6 +/- 5.1 pg/ml; p < 0.05 vs 0', +2'; +20'). The NE levels increased in both groups (NE stable angina: 0' = 105 +/- 31 pg/ml; +2' = 206 +/- 127 pg/ml; +5' = 223 +/- 135 pg/ml; p < .05 vs +2', +5'); (NE healthy subjects 0' = 85 +/- 10 pg/ml; +2' 165 +/- 49 pg/ml; p < 0.05 vs + 2'). In conclusion, our study showed that cold pressor test is a stimulus for the sympathetic system in both groups. The increased levels of ET-1 detected only in the patients with stable angina suggest that this peptide can take part to the pathogenesis of the coronary artery disease.     

Mechanistic study on liver tumor promoting effects of piperonyl butoxide in rats

Piperonyl butoxide, alpha-[2-(2-butoxyethoxy)ethoxy]-4,5-methylenedioxy-2-propyltol uene, is a widely used pesticide-synergist. Recently, results were reported indicating that piperonyl butoxide is a hepatocarcinogen in rat. Since the underlying mechanism was not elucidated, we examined the effects on rat liver cells in detail. For this purpose male F344 rats were administered piperonyl butoxide mixed in the diet at concentrations of 0 (negative control), 0.05, 0.2 or 2% for 2 days, 1, 2, and 4 weeks. As a positive control, phenobarbital was administered to rats for up to 4 weeks as a 0.1% solution in the drinking water. Increased liver weight, centrilobular hepatocellular hypertrophy due to increased smooth endoplasmic reticulum, decreased numbers and areas of connexin 32-positive spots per hepatocyte, and increased cell proliferation were observed in rats treated with 0.2 and 2% piperonyl butoxide. Similar results were obtained for 0.1% phenobarbital treated rats. Hepatocellular necrosis suggestive of hepatotoxicity was also observed in the 2% piperonyl butoxide group. These results indicate that the promoting mechanism of piperonyl butoxide in hepatocarcinogenesis is similar to that of phenobarbital, involving an ability to induce CYP isoenzymes and inhibit gap junctional intercellular communication. In addition, increased cell proliferation following hepatocellular necrosis may also play a role at high doses.     

Acute effects of morphine on regional brain levels of acetylcholine in mice and rats

Electrophoretic injection of Procion Yellow M-R4 into the ocellar tract of the worker bee has revealed the following: Two types of giant axon run from the lateral ocellus to the circumesophageal neuropile, where one branches ipsilaterally and the other contralaterally. A third type comes from the median ocellus and can be traced into the cervical connectives. The largest dendritic complex is in the circumesophageal neuropile; in addition, fiber endings have been demonstrated in the following areas: in the subretinal region, along the optic commissure, in the medulla interna, in the subesophageal ganglion and between the neurosecretory cells of the pars intercerebralis. -- The giant fibers are enclosed in a glial sheath. Three types of cell body are described. One is associated with the glia; another, larger cell type comprises giant-axon somata. The third type of cell is small, and cannot yet be identified. Some of the histological results are discussed with respect to the possible function of the ocellus.