The Effect of Substance P on the Superior Cervical Ganglion of the Cat

Abstract

Intra-arterial injections of substance P in doses from 10 to 30 units potentiated the response of the nictitating membrane to submaximal stimulation of the preganglionic sympathetic nerve, while higher doses (30 to 100 units) usually depressed the response. The stimulating action of acetylcholine on the superior cervical ganglion (as judged by the response of the nictitating membrane) was also potentiated by substance P. The responses of the nictitating membrane to adrenaline, noradrenaline and tyramine were potentiated by substance P as well. It is concluded that the potentiating effect of substance P on the response of the nictitating membrane to submaximal stimulation of the preganglionic sympathetic nerve is probably due to sensitization of acetylcholine receptors in the postsynaptic neurone. The present experiments do not explain how substance P potentiated the response to sympathomimetic amines.It has been shown that substance P may restore peristalsis when injected into the lumen of the isolated guinea-pig ileum in which the peristaltic reflex has been abolished by fatigue, by external or internal application of 5-hydroxytryptamine, or by lowering the temperature of the bath (Beleslin and Varagic, 1958). Substance P. when acting on the outside of the isolated guinea-pig ileum, blocks the peristaltic reflex (Beleslin and Varagic, 1959). In previous work some evidence was obtained that this block of peristalsis might be at least partly produced by the action of substance P on the intestinal ganglia. On the other hand, Lechner and Lembeck (1958) writing point magnifying the movements of the membrane ten times. The cervical sympathetic chain was divided and, when stimulated electrically, its peripheral end was placed on shielded electrodes and covered with liquid paraffin. For stimulation an electronic stimulator delivering square wave pulses was used. The pulses had a duration of 0.8 msec. and a frequency between 4 and 15 per sec.In some experiments the intra-arterial injections were made without occluding the external carotid artery, thus allowing the injected substance to act directly on the nictitating membrane.Substance P was extracted and purified according to the method described by Zetler (1956).The following substances were used: substance P. acetylcholine hydrochloride, adrenaline hydrochloride, noradrenaline bitartrate and tyramine hydrochloride. With the exception of substance P all doses are expressed in terms of the salts. RESULTSSubstance P and Sympathetic Nervous Stimulation. -The intra-arterial injection of substance P in doses from 10 to 100 units changed the response of the nictitating membrane to submaximal stimulation of the preganglionic sympathetic nerve. With the stimulation in periods of 5 sec. every minute, a series of contractions of the nictitating membrane was recorded as shown in Fig. 1. At C the external carotid artery was occluded, and an intra-arterial injection of 18 units of substance P increased the response of the nictitating membrane to the preganglionic stimulation. The...

Pharmacology of Autonomic Ganglia

“…Larger amounts of Substance P depress ganglionic transmission (14). No stimulation of the quiescent ganglion is observed.…”

Distribution and Biological Effects of Substance P

“…With 5000 units, spontaneous, but not induced, activity was reduced (28). Ganglionic transmission in the superior cervical ganglion of the cat was not affected by high doses of the purified SP (19), although a dual 753 reported using impure extracts (140,166,167). Caspers (10,168,169) correlated behavioral with bioelectrical changes in the unanesthetized rat after administration of an impure SP extract.…”

Pharmacologically Active Substances of Mammalian Origin

“…(a) Action of substance P on peripheral nervous structures : Beleslin and co-workers (14) found that intraarterial inj ections of substance P in doses from 10 to 30 units potentiated the response of the nictitating mem brane to submaximal stimulation of the sympathetic preganglionic nerve, whereas higher doses usually depressed the response. The stimulatory actions of acetylcholine on the superior cervical ganglion and of epineph rine, norepinephrine, and tyramine on the nictitating membrane were also potentiated by the polypeptide.…”