Neurotransmitter Releasing Effects of Two Quaternary Nicotine Analogues

Publisher Website
Google Scholar
Abstract
Two nicotine analogues, im‐monomethylnicotinium bromide (IMN) and 1–methyl‐3–(pyrro‐lidinomethyl)‐pyridinium bromide (MPP) have been studied with regard to their catechol‐amine releasing effects in the guinea pig and the rat. In doses of 10–30 mg/kg intraperitoneally IMN decreased the noradrenaline (NA) content of the guinea pig heart. In larger doses, up to 300 mg/kg, both substances caused 80–90 per cent NA depletion of the heart but not in the brain. Maximal effect was reached in 6–12 hn. In the decentralized sub‐maxillary gland the NA content decreased more slowly after IMN than in the normal gland. 6 hrs after sympathetic denervation of the gland the NA content was unchanged in the controls but fell to about one third of the normal after IMN, indicating a peripheral effect. Cold exposure (+2°) for 1 1/2 to 30 hrs did not increase the NA depleting effect of IMN in the rat heart. Catecholamine and vanilmandelic acid excretion in urine of the rat were not significantly increased after IMN and MPP even in doses of 300 mg/kg.It is concluded that the compounds release NA from the nerve terminals and that the release is enhanced by the normal nerve activity. Some reasons for the slow action are discussed.