Transmitter Coexistence in the Sympathetic Nervous System: Impact on Cardiovascular Regulation

Abstract

In recent years, evidence has been obtained for ATP and noradrenaline as cotransmitters in sympathetic nerves (cf. Burnstock and Sneddon 1985). The existence and storage of ATP together with noradrenaline in vesicles of sympathetic nerves was first reported by Schümann (1958). The author found that ATP and noradrenaline were stored in the vesicles in a molar ratio of 1 to 4. In the past decade, coexistence situations in sympathetic neurones have been described both for classical transmitters, such as noradrenaline and adrenaline, and for the coexistence of catecholamines and peptides (Hökfelt et al. 1980, Rand et a1. 1983). These results are of interest in the context of changes in adrenoceptor-catecholamine interactions, e.g. in the development of high blood pressure in both experimental and human essential hypertension, and may have also implications for the therapeutic action of β-receptor blocking drugs in essential hypertension.