Narcotic Antagonist-Induced Hypotension in the Spontaneously Hypertensive Rat

Document Type

Article

Language

eng

Format of Original

8 p.

Publication Date

9-1985

Publisher

Elsevier

Source Publication

Life Sciences

Source ISSN

0024-3205

Original Item ID

doi: 10.1016/0024-3205(85)90516-8

Abstract

Intravenous naloxone or naltrexone produced transient, dose-related reductions in the mean arterial pressure (MAP) and heart rate (HR) of urethane-anesthesized spontaneously hypertensive rats (SHRs). Yet these same doses of narcotic antagonists reduced HR but not MAP of normotensive Wistar-Kyoto rats (WKYs). Such effects were not observed upon administration to SHRs of increasing doses of methylnaltrexone, which possesses no central activity. (+)-Naloxone, which does not block opiate receptors, reduced HR but not MAP of both SHRs and WKYs. These findings indicate that SHRs and WKYs differ in their MAP and HR responses to narcotic antagonists. The high doses required for effect plus the brevity of the responses suggest that these drug effects are perhaps not μ-opiate receptor-mediated; however, the methylnaltrexone and (+)-naloxone findings clearly implicate a central specificity of action. We conclude that narcotic antagonist-induced changes in MAP and HR in SHRs are possibly specific and central in origin yet not mediated by μ-opiate receptors.

Comments

Life Sciences, Vol. 37, No. 9 (September 1985): 819-826. DOI.

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