Physiology of Muscarinic Receptor-Operated Nonselective Cation Channels in Guinea-Pig Ileal Smooth Muscle

Stimulations of autonomic nerves in smooth muscle often evoke both fast and slow excitatory junction potentials (EJPs), which are thought to involve activations of several distinct types of nonselective cation channels (NSC channels). The ACh-activated NSC channel in guinea-pig ileum (Ins.ACh) is one probably responsible for the slow EJP and seems to undergo various regulations. This short paper will review the physiology of Ins.ACh, with particular emphasis on its dynamic interactions with other physiologically important factors such as the membrane potential, [Ca2+]i and pH.