AJP - Heart and Circulatory Physiology, Vol 249, Issue 2 272-H277, Copyright © 1985 by American Physiological Society
Intracoronary naloxone in hemorrhagic shock: dose-dependent stereospecific effects
R. B. Lechner, N. J. Gurll and D. G. Reynolds
Treatment with naloxone improves cardiovascular function and survival in a
variety of shock models, and numerous sites and mechanisms for its action
have been proposed. Data presented in this article support the hypothesis
that in hemorrhagic shock naloxone exerts its beneficial hemodynamic
effects by acting primarily at cardiac opiate receptors. Naloxone or its
stereoisomer (d-naloxone) were administered intravenously (iv) and directly
into the coronary circulation (ic) in dogs anesthetized with pentobarbital
sodium and subjected to hemorrhagic shock. Treatment with naloxone (2.0
mg/kg iv or 0.2 mg/kg ic) resulted in significant improvements in arterial
pressure, myocardial contractility, and cardiac output. Treatment with
saline or naloxone (0.2 mg/kg iv) were without beneficial effect. The
hemodynamic responses to naloxone administered into the coronary
circulation were dose dependent and stereospecific. These data support the
hypothesis that naloxone exerts its salubrious effects in canine
hemorrhagic shock by acting at cardiac opiate receptors.
