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Biomedical subjects

F Clostre

Publications and source records attributed to F Clostre.

At least 55 records · Page 3Linked to original sources
PubMed1983

Effects of an extract of Ginkgo biloba and diverse substances on the phasic and tonic components of the contraction of an isolated rabbit aorta.

1. The effects of phentolamine, propranolol, D 600, theophylline, papaverine and an extract of Ginkgo biloba were studied with respect to the two phases of the contractile response induced by norepinephrine in an isolated rabbit aorta. 2. Phentolamine (3 x 10(-6) M) inhibits the rapid phase of the contraction of the rabbit aorta brought on by norepinephrine (NE) 10(-5) M more strongly than the tonic phase. Propranolol (10(-6) M) potentiates this rapid phase. 3. D 600 inhibits the slow phase with an EC50 = to 3.8 x 10(-8) M. 4. Papaverine and theophylline increase the relaxation that follows the rapid phase of contraction. The slow phase is inhibited only by papaverine. 5. The extract of Ginkgo biloba (Gb) at a concentration of 3 mg/ml has the same type of effect as papaverine 3 X 10(-5) M.

Animals↗
PubMed1982

Inhibition of food intake in the rat by cyproheptadine.

In a model of conditioned feeding behavior, oral administration of cyproheptadine (1-100 mg/kg), 30 min before presentation of food, produced a dose-dependent reduction of food intake in the rat (ED50 congruent to 17 mg/kg during the 1st h of testing). This anorexic effect persisted for at least 24 h. These results provide further evidence that under certain conditions cyproheptadine, which is used as an orectic agent in man, can produce anorexia.

Animals↗
PubMed1982

THIP inhibits feeding behavior in fasted rats.

The effects of 4,5,6,7-tetrahydroisoxazolo-[5,4-c]pyridin-3-ol (THIP) were compared with those of d-amphetamine and GABA in fasted rats. Intravenously-administered THIP produced a dose-dependent decrease in food consumption (ED50 congruent to 1.5 mg/kg) by an action that was not reversed by prior subcutaneous or simultaneous intravenous (IV) injection of bicuculline. d-Amphetamine-SO4 also produced a decrease in food consumption in this model (ED50 congruent to 0.2 mg/kg, IV). Unlike THIP, GABA (in doses up to 100 mg/kg, IV) did not produce a marked anorexigenic effect. These results provide further evidence that THIP can penetrate the "blood-brain barrier", and that central GABA-ergic systems are involved in controlling food intake.

Animals↗
PubMed1982

A regional difference in the in vitro response of the rabbit vena cava to norepinephrine.

1. Isotonic concentration-response curves were constructed for the contractile effects of norepinephrine (NE) in venous strips prepared from the caudal and rostral portions of rabbit vena cava; in some cases the venous strips were damaged by scraping their inner (endothelial) surface with a scalpel. 2. In both control and damaged venous strips, the rostral portions exhibited a higher affinity and a greater capacity of contraction to applied NE than caudal portions. 3. Such results might be explained by a difference in the distribution (or characteristics) of alpha-adrenoceptors and/or by a difference in the ratio of circular to longitudinal muscular elements in these two regions of the vena cava. 4. These findings should be considered when designing experiments aimed at determining the effects of alpha-adrenoceptor agonists on rabbit vena cava.

Animals↗
PubMed1982

Studies on food intake in the fasted rat.

1. The effects of orally- and intravenously-administered d-amphetamine-SO4, fenfluramine-HCl and cocaine-HCl on food intake in the fasted rat were compared. 2. During the first hour after presentation of food to the animals, ED50 values for suppression of food intake after intravenous injection were: d-amphetamine-SO4, 0.1 mg/kg; fenfluramine-HCl, 0.6 mg/kg; cocaine-HCl, 1.0 mg/kg, ED50 values for suppression of food intake after oral administration were: d-amphetamine-SO4, 0.3 mg/kg; fenfluramine-HCl, 0.7 mg/kg; cocaine-HCl, 9 mg/kg. 3. Over a 4 hr test period, d-amphetamine, fenfluramine and cocaine produced dose-dependent anorexigenic effects only when orally administered. 4. Orally-administered quipazine-maleate and mazindol also decreased food intake, their respective ED50 values being 7 mg/kg and 1.2 mg/kg for the first hour of testing; the anorexigenic effect of mazindol appeared to be more sustained than those of the other anorexigenic agents tested in that it was evident on the day after drug administration. 5. Orally-administered diazepam increased food intake on the day of its administration, but decreased food intake on the day after its administration. 6. In addition to providing further evidence for the effects of several typical anorexigenic agents, the model described might be useful for further studies on anorexigenic agents and minor tranquillizers.

Animals↗
PubMed1982

Effects of diltiazem on renovascular-hypertensive and on normotensive rats.

1. The effects of 10-min perfusions of diltiazem (o.1-2.5 mg/kg, i.v.) on arterial blood pressure were studied in anesthetized renovascular-hypertensive and in normotensive rats. 2. Diltiazem produced a dose-dependent decrease in blood pressure in hypertensive rats (ED50 congruent to 1 mg/kg). 3. Diltiazem also decreased blood pressure in normotensive rats, but this action was less sustained than in hypertensive rats. 4. These results support the contention that diltiazem might be useful for treating arterial hypertension.

Animals↗
PubMed1982

Effects of Ginkgo biloba on arterial smooth muscle responses to vasoactive stimuli.

1. An extract of Ginkgo biloba (Gb), at a concentration (100 microgram/ml) that did not provoke isometrically-recorded contractions of rabbit aorta, was tested on the contractile effects of norepinephrine (NE), serotonin (5-HT) and dopamine (DA). 2. Gb potentiated the contractile effect of NE (reduced the EC50 from 75 to 36 nM), but had no obvious action on the contractile effects of 5-HT or DA. 3. These results indicate that low concentrations of Gb might influence catecholaminergic systems by an indirect mechanism.

Animals↗
PubMed1982

Lack of effect of the peptide pyro-Glu-His-Gly-OH on food consumption in mice and rats.

1. Single subcutaneous injections (0.5-10 mg/kg) or repeated oral administration (5 mg/kg, twice daily for 3 or 5 days) of the proposed anorexigenic peptide pyro-GLU-HIS-GLY-OH did not affect food intake in the mouse. 2. Single intravenous injections (0.05-1 mg/kg) or daily intravenous injections (0.3-10 mg/kg, for 5 days) of pyro-GLU-HIS-GLY-OH did not affect food intake in the rat. 3. These results, together with results obtained recently by other workers, indicate that pyro-GLU-HIS-GLY-OH does not have anorexigenic properties in rodents.

Animals↗
PubMed1982

Effects of an extract of Ginkgo biloba on rabbit isolated aorta.

1. Extract of Ginkgo biloba (Gb) provoked a dose-dependent contraction of spirally-cut rabbit aortic strips (EC50 congruent to 1.0 mg/ml) by an action that was antagonized by phentolamine (10(-7) M). 2. Inhibitors of catecholamine re-uptake, cocaine (10(-5) M) and desipramine (10(-7) M) potentiated the contractile effect of norepinephrine (NE), but inhibited the contractile effects of Gb and tyramine. 3. A comparison of the actions of Gb, NE and tyramine using aortic strips prepared from control and reserpine-treated rabbits revealed that reserpine treatment increased the response to NE but decreased the response to Gb and tyramine. 4. The contractile action of Gb on rabbit isolated aorta involves, at least in part, a release of catecholamines from endogenous tissue stores.

Animals↗
PubMed1982

Effect of an extract of Ginkgo biloba on the isolated ileum of the guinea-pig.

1. The effects of an extract of Ginkgo biloba (Gb) were studied using the guinea-pig isolated ileum. 2. Using isometric recording, the dose-response relation for the action of Gb was complex, and at 400 micrograms/ml was reproducibly biphasic--a relaxation followed by a contraction. 3. Droperidol (3 X 10(-7) M - 10(-6) M), cyproheptadine (10(-7) M), and diphenhydramine (10(-7) M) prolonged the relaxation and usually decreased the amplitude of the contraction produced by Gb (400 micrograms/ml), whereas phentolamine, hexamethonium, methysergide, or cimetidine (10(-7) or 10(-6) M) did not affect the response to Gb. 4. The action of Gb on the guinea-pig ileum might involve mechanisms associated with dopamine and/or histamine.

Animals↗
PubMed1982

A comparison of the dose-response effects of captopril in anesthetized normotensive and renovascular hypertensive rats.

1. Dose-response effects of captopril in an acute model of renovascular hypertension in the anaesthetized rat and in normotensive anaesthetized rats were compared. 2. Intravenous infusions of captopril lowered the blood pressure of both hypertensive and normotensive rats, its minimal active dose being about 0.05 mg/kg. 3. The 0.1 mg/kg dose of captopril normalized the blood pressure of hypertensive rats. 4. The model described herein might be useful for screening inhibitors of the angiotensin-converting enzyme.

Animals↗
PubMed1982

Effects of different diuretics on tetracycline-induced hyperuraemia and hypercreatininaemia in the rat.

Tetracycline injection (45 mg/kg, i.v.) produced increases in plasma urea and creatinine levels in rats. The greatest increases occurred after 24 hr for urea and after 6 hr for creatinine, the latter effect persisted for at least 30 hr. The actions of six diuretics (acetazolamide, bumetanide, chlorothiazide, chlorthalidone, triamterene and indapamide) given orally either as pretreatment (1 hr before tetracycline injection) or post-treatment (4 hr after tetracycline injection) were examined. When given as pretreatments, all six diuretics reduced the hyperuraemia, and generally the hypercreatininaemia, that existed 24 hr after tetracycline injection. In contrast, when given as post-treatments, only bumetanide reduced the increase in urea and creatinine levels. It is postulated that this protective action of diuretics could occur by their displacement of tetracycline molecules from protein binding sites or by a-direct action on renal function.

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