Effect of Morphine on Some Sympathetically Innervated Effectors

Abstract

Morphine, in doses of 0.5 to 55 mg/kg, inhibited contraction of the nictitating membrane of the cat following stimulation of the postganglionic sympathetic nerve fibres. Morphine was more effective at low than at high frequencies of stimulation, independently of the size of contraction of the membrane; the speed of contraction was reduced at all frequencies. Cocaine potentiated the contraction of the nictitating membrane following nerve stimulation more at low than at high frequencies, and antagonized the action of morphine. These findings, and the absence of an effect of morphine on the action of injected noradrenaline, make it likely that morphine interferes with the release of noradrenaline from the postganglionic nerve endings in the nictitating membrane. Morphine had no effect on the cardioaccelerator action of the cardiac nerves and inconsistent results were obtained on the emptying of the spleen after stimulation of the splenic nerves.

An Electrophysiological Analysis of the Effects of Morphine on the Calcium Dependence of Neuromuscular Transmission in the Mouse Vas Deferens

“…Morphine does not reduce the noradrenaline output from the vas deferens (Henderson & Hughes, 1976) or the cat nictitating membrane (Cairnie, Kosterlitz & Taylor, 1961) during trains of high-frequency impulses, This is consistent with the effects of morphine on the ej.p. By the time a steady-state e.j.p.…”

The Action of Morphine‐like Drugs on Impulse Transmission in Mammalian Nerve Fibres

“…In six experiments we found no evidence which suggested that morphine, in doses large enough to depress the responses of the nictitating membrane (Cairnie et al, 1961), interfered with impulse transmission. In the example shown in Fig.…”

“…It has been shown (Kosterlitz & Taylor, 1959;Cairnie et al, 1961) that the depressant action of morphine on the responses of the rabbit sinoatrial node to vagal stimulation and on the response of the cat nictitating membrane to postganglionic sympathetic stimulation is greater at low than at high stimulus frequen-cies. We were therefore particularly interested in the possible action of morphine on action potentials evoked by single stimuli, but included also experiments with repetitive stimulation.…”

Hyposensitivity to drugs induced by morphine and some related substances in the cat

“…Just as tolerance is not shown clinically to all the central actions of morphine, in the present paper there is one action which is not suppressed, namely the potentiating action of adrenaline on the tibialis anterior response to direct muscle stimulation (Huidobro, Cubillos & Eyzaguirre, 1952). Morphine has already been shown to have a number of depressant actions: for example, on cerebral metabolism (Takemori, 1962;Clouet, Ratner & Williams, 1966;Clouet & Ratner, 1968): on the responses of the nictitating membrane to pre-or postganglionic stimulation (Trendelenburg, 1957;Cairnie, Kosterlitz & Taylor, 1961;Gyang, Kosterlitz & Lees, 1964); on the cardiac responses to vagal stimulation (Kosterlitz & Taylor, 1959;Kennedy & West, 1967) and on the release of the chemical transmitter, acetylcholine (Paton, 1957;Schaumann, 1957). Morphine can suppress the actions of a number of drugs at the peripheral receptors (Trendelenburg, 1957;Kosterlitz & Robinson, 1958 Cairnie et al (1961) found that morphine did not decrease the nictitating membrane contraction induced by adrenaline or noradrenaline.…”