In:
Canadian Journal of Physiology and Pharmacology, Canadian Science Publishing, Vol. 70, No. 7 ( 1992-07-01), p. 983-989
Abstract:
The effects of TA-3090 (clentiazem) and nifedipine on basal sympathoadrenal activity and on the adrenal medullary response during splanchnic nerve stimulation were studied in dogs anesthetized with sodium pentobarbital. Plasma concentrations of epinephrine and norepinephrine were measured in aortic and adrenal venous blood before and after acute administration of the drugs, as well as during left splanchnic nerve stimulation before and after administration of drugs. Following intravenous injections, TA-3090 (30, 100, and 300 μg/kg) did not affect basal circulating catecholamine levels, whereas nifedipine (10, 30, and 100 μg/kg) markedly increased aortic epinephrine and norepinephrine concentrations in a dose-dependent manner in correlation with progressive decreases in mean arterial pressure. The changes in aortic epinephrine and norepinephrine concentrations were inversely related to those in mean arterial pressure (r = 0.603, p 〈 0.01; r = 0.536, p 〈 0.01; respectively). In response to direct splanchnic nerve stimulation (2 Hz, 2 ms, 1 min, 12 V), adrenal venous epinephrine and norepinephrine concentrations significantly increased, with a high degree of reproducibility. The catecholamine responses to splanchnic nerve stimulation were not affected by either TA-3090 or nifedipine at any dose tested. The present results suggest that the increases in circulating catecholamine levels following nifedipine administration are due to baroreflex activation secondary to the drug-induced hypotension. The study indicates that both TA-3090 and nifedipine did not significantly affect L-type Ca 2+ channels related to catecholamine release in the adrenal medulla under the present experimental conditions.Key words: calcium antagonists, nifedipine, clentiazem, adrenal gland, catecholamines, splanchnic nerve, baroreflex.
Type of Medium:
Online Resource
ISSN:
0008-4212
,
1205-7541
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1992
detail.hit.zdb_id:
2004356-9
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