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Biomedical subjects

G Gaillard-Plaza

Publications and source records attributed to G Gaillard-Plaza.

12 recordsLinked to original sources
PubMed1985

[Role of the adrenal medulla in the effect of antihypertensive drugs].

Recent studies have suggested a role for adrenaline in the pathogenesis of essential hypertension. In the present study, the effects of several anti-hypertensive agents were compared in normal (plasma adrenaline concentration: 0.267 + 0.040 ng/ml) and adrenomedullectomised (plasma adrenaline concentration: 0.063 + 0.011 ng/ml; p less than 0.01) dogs. The hypotensive and tachycardic effects of phentolamine (1.5 mg/kg i.v.) or dihydralazine (1 mg/kg i.v.) were the same in the two groups of dogs. Verapamil (0.2 mg/kg i.v.)-induced hypotension was less pronounced in dogs without adrenal medulla. In these adrenomedullectomised dogs, clonidine (10 micrograms/kg i.v. or 1 microgram/kg i.c.) elicited tachycardia and its hypotensive properties were delayed. In dogs with neurogenic hypertension, the antihypertensive properties of propranolol (1 mg/kg i.v.) remained unchanged. These results show the importance of adrenal medulla in the antihypertensive action of clonidine, or verapamil. These agents (but not dihydralazine, propranolol or phentolamine) could reduce adrenaline secretion from the adrenal medulla.

Adrenal Medulla↗
PubMed1985

Influence of naloxone on the antinociceptive effects of some antidepressant drugs.

The antinociceptive effects of tricyclic and atypical antidepressants were studied using the rat tail mechanical method. Clomipramine produced analgesia at the doses of 30 and 40 mg/kg, desimipramine at 10, 20 and 40 mg/kg, maprotiline at 20 and 30 mg/kg, mianserin at 30 mg/kg, nomifensine at 1, 2.5 and 5 mg/kg, indalpine at 10, 20 and 40 mg/kg, viloxazine at 60 and 80 mg/kg. Naloxone (0.8 mg/kg) abolished the antinociceptive action of these antidepressant drugs. These results suggest that the antinociceptive activity of these six antidepressant drugs in acute experimental pain could involve opiate mechanisms.

Analgesics↗
PubMed1984

Naloxone suppresses the vasodepressor action of captopril in the anaesthetized dog.

The effects of intracisternal injection of captopril (0.3 mg/kg) on the systolic pressor response elicited by afferent stimulation of the vagus were investigated in the anaesthetized dog. The captopril-induced decrease in the systolic pressor response to vagal stimulation was reversed by a subsequent injection of naloxone (0.1 mg/kg i.v.). These results suggest the involvement of central opioid mechanisms in the hypotensive properties of captopril.

Animals↗
PubMed1983

[Analgesic properties and plasma concentrations of clomipramine in chronic pain].

The analgesic effect of clomipramine and the possible relationships between the antalgic action, the doses and the plasma levels of this tricyclic drug have been studied in 15 patients with chronic pain induced by nervous lesions determining a deafferentiation. Eight of 15 patients treated with clomipramine (100 mg/IV during 10 days and then 150 me per os) reported a significant improvement (up to 50 per cent during 3 to 18 months). The study of the partial coefficients of correlation did not show a relationship between plasma levels and analgesia in the total population or in the subgroup of the 8 improved patients. These results confirm the analgesic properties of clomipramine and suggest that regular monitoring of plasma levels of clomipramine does not appear of practical interest in the treatment of chronic pain.

Adult↗
PubMed1983

[Endomorphins and experimental analgesic action of amitriptyline].

The analgesic effect of several doses of amitriptyline was studied in rats. The lower doses of the tricyclic compound showed clear analgesic properties whereas the higher doses remained ineffective. Naloxone, deprived of effect when administered alone, reduced the antinociceptive action of amitriptyline. These results suggest that the analgesic properties of the tricyclic compound could involve endorphin central systems.

Amitriptyline↗
PubMed1981

Influence of naloxone and methysergide on the analgesic effect of clomipramine in rats.

The effects of the tricyclic antidepressant clomipramine were studied in two analgesic tests in rats: (1) vocalization threshold response; and (2) scored behavioral response to electric shock to the tail. Clomipramine (20-50 mg/kg i.p.) produced analgesia, decreasing behavioral response scores and increasing vocalization threshold. Morphine also reduced the response scores in the second test. Naloxone (0.8 mg/kg i.p) or methysergide (20 mg/kg i.p.) (no effect when given alone) abolished the analgesic effect of clomipramine as evaluated by vocalization threshold response. Naloxone alone (0.6 or 2 mg/kg i.p.) increased the behavioral response at 20 and 30 V but did not modify the score at 40 V. Naloxone reduced the analgesic effect of clomipramine or morphine in the behavioral test. These results suggest that the analgesic effect of clomipramine could involve both serotonergic and endorphin central systems.

Analgesics↗
PubMedDate not supplied

Influence of naloxone on the captopril-induced decrease in vagal pressor reflexes.

The effects of intracisternal injection of captopril (0.3 mg/kg) on the pressor responses elicited by afferent stimulation of the vagus were investigated in the anaesthetized dog. The captopril-induced decrease in the systolo-diastolic pressor response to vagal stimulation was reversed by subsequent injection of naloxone (0.1 mg/kg, i.v.). These results suggest the involvement of central opioid mechanisms in the hypotensive properties of captopril.

Animals↗
PubMedDate not supplied

Influence of methyldopa and bromocriptine on negative pressure breathing-induced diuresis.

The effects of methyldopa, a central alpha 2-agonist, and bromocriptine, a dopaminergic drug, on negative pressure breathing-induced diuresis were studied in the dog. Methyldopa (20 mg/kg i.v. during 20 min) or bromocriptine (0.3 mg/kg i.v.) suppressed the diuretic reflex without changing blood pressure. Since negative pressure breathing-induced diuresis is mainly due to an inhibition of vasopressin secretion, it is suggested that central alpha 2-adrenoceptors and dopaminergic receptors play an inhibitory role in mediating vasopressin release to non osmotic stimuli.

Animals↗
PubMedDate not supplied

Influence of bromocriptine on the pressor responses to afferent nervous stimulation.

The effects of intravenous bromocriptine were studied on the systolic pressor responses elicited by stimulation of afferent nerves (vagus, saphenous and superior laryngeal nerves) in urethane anaesthetized dogs. Bromocriptine alone decreased these pressor responses. Pretreatment with sulpiride failed to modify the depressor action of bromocriptine on the pressor responses to vagal stimulation. In contrast, sulpiride prevented bromocriptine-induced decrease in the pressor responses elicited by saphenous or laryngeal activation. These data confirm the potential antihypertensive properties of bromocriptine and show that this effect is only partly due to an activation of prejunctional dopaminergic receptors. They suggest that the mechanism of the antihypertensive action of bromocriptine may vary according to the level of blood pressure, the kind of arterial hypertension and the species.

Animals↗
PubMedDate not supplied

[Influence of nephrectomy on the antihypertensive effects of propranolol in the dog (author's transl)].

1. The effect of bilateral nephrectomy (24 hours before) on the antihypertensive action of dl-propranolol (1 mg/kg iv) was studied in acute neurogenic hypertensive dogs. 2. Bilateral nephrectomy induced an increase in plasma urea and creatinine, a decrease in protein values but did not change the other plasma values (table I). 3. Propranolol always induced a decrease in blood pressure (fig. 1) and heart rate (fig. 2) in bilateral nephrectomized dogs. 4. These results suggest that renal mechanisms (especially modifications of renin release) did not play a predominant or exclusive role in the antihypertensive action of beta-blocking agents under our experimental conditions.

Animals↗