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Biomedical subjects

G Peeters

Publications and source records attributed to G Peeters.

At least 73 records · Page 4Linked to original sources
PubMed1976

Effect of isoproterenol on urinary function in goats.

Intraventricular administration of small doses (6.3-19-58 ng/kg/min) of isoproterenol (ISO) in non-hydrated goats produced a diuretic response, a decrease in urinary Na+, K+ and Cl- excretion and an increase in free water clearance. The diuretic response of ISO could be blocked by propranolol, but not by phentolamine. The data suggest that hypothalamic beta-adrenoceptors are involved in the inhibition of ADH release.

Animals↗
PubMed1976

Effect of intraventricular administration of isoprenaline on urinary function in the goat.

Intraventricular infusion of small doses of isoprenaline (ISO) in conscious non-hydrated goats produced a significant diuretic response, as well as a decrease in the excretion rate of Na+, K+ and Cl- in the urine; these effects were dose-dependent. An increase in free water clearance was observed as well. Pretreatment with propranolol, injected into the 3rd ventricle, completely abolished the ISO-induced diuretic effects, whereas phentolamine was ineffective. The data suggest that hypothalamic beta-adrenoreceptors are concerned with an inhibition of vasopressin release, inducing a diuretic response.

Animals↗
PubMed1976

Induction of lactation in virgin goats by perhenazine.

Chronic implantation of a small amount of perphenazine into the median eminence (M.E.) of virgin female goats caused mammary development and artificial induction of lactation. Sham implantations in the M.E. and implantation of perphenazine in other sites of the hypothalamus were ineffective.

Animals↗
PubMed1975

Influence of sympathomimetic drugs on the motility of bovine teat muscles.

Spontaneous rhythmical contractions of the teats of living cows were recorded by a plethysmographical method. These contractions were inhibited by isoproterenol, adrenaline, isoxsuprine and phentolamine, but were activated by phenylephrine. Noradrenaline induced activation which was often followed by inhibition. These results obtained in vivo were in agreement with responses obtained in vitro. Apparently beta sympathomimetic effects are evoked easily under in vivo conditions.

Animals↗
PubMed1975

Influence of serum free fatty acid levels on growth hormone secretion in lactating cows.

The influence of intravenous injections or infusions of insulin (0-2 i.u./kg), propranolol (150 mg), 3,5-dimethylpyrazole (3 mg/kg), 3,5-dimethylisoxazole (0-08 mg/kg), glucose (0-5 g/kg), nicotinic acid (120 mg/kg), arginine (0-5 g/kg) or butyrate (0-5 mmol/kg) on plasma glucose levels, and on serum concentrations of growth hormone and free fatty acids of lactating cows was investigated. In all of these experiments we noted an increase in the level of growth hormone. This increase was not a direct consequence of alterations in the glucose concentration, since the growth hormone peak occurred both during a decrease (insulin, 3,5-dimethylisoxazole, nicotinic acid and butyrate tests), and during an increase of the glucose level (glucose, arginine and propranolol tests), whereas the glucose concentration remained unchanged during the 3,5-dimethylpyrazole experiments. However, in each instance a precipitous fall of the free fatty acid level was noted. The glucose, growth hormone, and free fatty acid levels of lactating cows were not affected by either i.v. injection or infusion of saline.

Animals↗
PubMed1975

Effect of intraventricular administration of noradrenaline on water diuresis in goats.

Duriing water diuresis in conscious goats, noradrenaline (NA), its antagonists phentolamine, phenoxybenzamine and propranolol and also atropine were administered into the 3rd ventricle. The subsequent effects on water diuresis and on the excretion rates of Na+, K+ and Cl- were investigated. Infusion of NA into the 3rd ventricle induced a strong and significant antidiuretic response and a decrease in the Na+ : K+ excretion ratio; these effects were dose-dependent. High doses of NA produced a significant increase in urinary K+ excretion. Similar results were observed after i.v. administration of arginine-vasopressin. Pretreatment with phentolamine injected into the 3rd ventricle produced a dose-dependent inhibition of the NA-induced antidiuretic effects. Phenoxybenzamine also blocked the response to NA but a dose-response relationship was not apparent. Atropine and propranolol did not block the response to NA.

Animals↗
PubMed1974

Metabolism of (14C)citrulline in the perfused sheep and goat udder.

1. A lactating-sheep mammary gland was perfused for 12h in the presence of l-[2-(14)C]-citrulline and received adequate quantities of glucose, acetate and amino acids. Two lactating-goat udders were similarly perfused in the presence of either l-[carbamoyl-(14)C,-2-(14)C]citrulline or l-[carbamoyl-(14)C,1-(14)C]citrulline and l-[4-(3)H]arginine. 2. In these experiments, [(14)C]citrulline was substantially oxidized to CO(2) and converted into arginine and proline of casein. 3. The specific radioactivities of arginine, ornithine and proline of the plasma increased after passage through the udders, demonstrating that [(14)C]citrulline is metabolized by the mammary gland. 4. The presence of two unknown radioactive metabolites of [(14)C]citrulline was detected in the perfusate. These substances were not found after incubation in vitro of oxygenated blood in the presence of the radioactive precursor. 5. From these experiments, it is concluded that citrulline is metabolized in mammary tissue by way of arginine to urea, ornithine and proline.

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