Electrical and Chemical Features of Sympathetic Nerve-Smooth Muscle Junctions

Abstract

Neurotransmission at the mammalian sympathetic nerve-smooth muscle junction has several unique features that set it apart from better-investigated junctions, such as the one between somatic nerves and skeletal muscle. In the rodent vas deferens, a model tissue for the study of sympathetic neuroeffector processes, both the electrical and the chemical events that take place during neurotransmission have resisted adequate explanation for many years. For instance, the factors that determine the time courses of the excitatory junction potentials that occur in the smooth muscle cells following neuronal transmitter release are not fully known. Furthermore, there has been controversy about the identity of the chemical neurotransmitter that mediates the excitatory junction potentials, as transmission by the classical sympathetic transmitter noradrenaline fails to account for these electrical events. Recent studies have helped to shed light on both these issues and will be discussed in this short review.