Cardiovascular effects of morphine, pethidine, diamorphine and nalorphine on the cat and rabbit

Abstract

Summary1. The predominant effect of morphine, diamorphine, pethidine or nalorphine on the blood pressure of the anaesthetized cat or rabbit is hypotension although, occasionally, a pressor action may predominate or intervene. 2. Possible mechanisms of the depressor phases of action have been studied on cardiac and vascular preparations both in situ and in vitro. 3. While in the whole animal, catecholamine release from the adrenal medulla and histamine liberation may be implicated in the responses, the vasodilator and vascular relaxant actions of morphine and, probably, pethidine, nalorphine and diamorphine on the isolated preparations are not mediated by the liberation of known peripheral transmitters or autacoids or by interaction with their specific receptors.

Xenon augmented hypothermia reduces early lactate/N‐acetylaspartate and cell death in perinatal asphyxia

“…Clinical trials suggest that therapeutic hypothermia is well tolerated,51 although associated with increased inotropic support,52, 53 which may be physician dependent 53. Isoflurane decreases cardiac contractility,54 and opiates such as morphine are associated with hypotension55; thus, the combined cardiosuppressive effects of anesthesia, opiates, and hypothermia may explain our findings. Inhaled xenon itself has good cardiostability in swine56 and humans, with the exception of small heart rate decreases 54.…”

Histamine-Releasing and Allergenic Properties of Opioid Analgesic Drugs: Resolving the Two

“…Since these early studies implicating morphine in histamine release, many investigations of the histamine releasing and cardiovascular effects of morphine and other opioids have been undertaken on live laboratory animals and their cardiovascular tissues (see extensive list of references in Grundy 42 ). Evidence of the release of histamine by alkaloids of opium was provided by Nasmyth and Stewart 43 , who showed that wheals caused by morphine in human skin were reduced by antihistamines and Feldberg and Paton 44,45 who detected several micrograms of histamine in the effluent after injection of opium alkaloids into the artery of isolated perfused cat gastrocnemius muscle.…”

“…They also showed that histamine was released from cat skin and raised levels were found in plasma after intravenous injection of morphine and other opium alkaloids. In summarising in 1971 some of the main findings of animal studies accumulated over more than 40 years, Grundy 42 concluded that when morphine or pethidine was given intravenously to anesthetised laboratory animals, the predominant effect recorded was hypotension, sometimes with a transient ressor effect due to the release of catecholamines 46 .…”

Effects of pethidine and nalorphine on the mechanical and electrical activities of mammalian isolated ventricular muscle

“…Whilst this paper is primarily concerned with the depressant effects of pethidine on the myocardium, mention must first be made of the initial phase of positive inotropism which has often been encountered. On the basis of earlier experiments (Grundy, 1971) with pethidine on more intact preparations, especially the Langendorff preparation of the guinea-pig heart, this initial stimulation of cardiac contraction produced by pethidine and by nalorphine might possibly result from the release of endogenous catecholamines or histamine or of both.…”

“…The following circulatory actions of pethidine and of nalorphine have been reported previously (Grundy, 1971). In the anaesthetized cat or rabbit, after intravenous doses of 2-10 mg/kg pethidine, the blood pressure responses typically consist of transient pressor or depressor changes preceding a more prolonged hypotensive phase, which is the result of direct musculotropic peripheral vasodilation and cardiac depression.…”