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Naloxone‐induced reversal of clonidine, but not hydralazine, hypotension
Author(s) -
Bennett Debra A.,
DeFeo John J.,
Elko Edward E.,
Lal Harbans
Publication year - 1982
Publication title -
drug development research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.582
H-Index - 60
eISSN - 1098-2299
pISSN - 0272-4391
DOI - 10.1002/ddr.430020207
Subject(s) - clonidine , hydralazine , (+) naloxone , medicine , blood pressure , anesthesia , antagonist , opiate , receptor
Normotensive rats of the Sprague‐Dawley strain were administered either the centrally acting hypotensive drug clonidine (0.16 mg/kg IP) or the peripherally acting hypotensive drug hydralazine (1.25 mg/kg IP) to induce reliable hypotension (blood pressure reductions of 60–90 mm Hg), as measured by a tail cuff procedure. The opiate antagonist, naloxone (10–20 mg/kg IP), reversed clonidine but not hydralazine hypotension. Naloxone also failed to reverse hydralazine's hypotensive action in rats made hypertensive by renal ligation. Naloxone's reversal of clonidine (0.01 mg/kg IV) hypotension was confirmed in experiments in which blood pressure was measured through direct cannulation of the carotid artery. It is suggested that naloxone's antagonism of clonidine hypotension is located at a central nervous system site, and that clonidine hypotension may be mediated through an interaction with the brain opiate systems.