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BLOCKADE OF THE CENTRAL HYPOTENSIVE EFFECT OF CLONIDINE BY α‐ADRENORECEPTOR ANTAGONISTS IN RATS, RABBITS AND DOGS
Author(s) -
Bogaievsky Dominique,
Bogaievsky Yvan,
TsoucarisKupfer Danita,
Schmitt Henri
Publication year - 1974
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1974.tb00573.x
Subject(s) - clonidine , phentolamine , phenoxybenzamine , tolazoline , blood pressure , propranolol , endocrinology , medicine , cisterna magna , blockade , anesthesia , receptor , cerebrospinal fluid
SUMMARY 1. Clonidine and three α‐adrenoreceptor blocking agents were injected into the cisterna magna of rats, rabbits and dogs. Clonidine (1 μg. kg −1 ) induced a fall in blood pressure in the three species. 2. Phentolamine, tolazoline and phenoxybenzamine (100 μg. kg −1 ) induced a fall in blood pressure in rats, but only phentolamine was effective in rabbits, and none of these drugs significantly altered blood pressure in dogs when given intracisternally. 3. A subsequent administration of clonidine after recovery of blood pressure no longer decreased blood pressure in rats and rabbits. 4. In dogs the effects of clonidine were antagonized by tolazoline and phentolamine, but not by phenoxybenzamine. 5. These results indicate that clonidine stimulates central α‐adrenoreceptors to produce a decrease in blood pressure, but the structure of these receptors may vary according to animal species.