Calcium Channels in Intestinal Smooth Muscle

Abstract

Tension in intestinal smooth muscle is critically dependent on electrical activity. In the small intestine this activity comprises frequent spontaneous action potentials often superimposed on slow waves of depolarization. It is usually calcium (Ca)-influx through voltage-gated Ca channels that generates the depolarization of the action potential and so these ionic channels have been the subject of many investigations and much is now known of their biophysics and pharmacology (1). Also, Ca channels in intestinal smooth muscle are subject to modulation by neurotransmitters and local hormones. Recent observations on these agonist effects are described.