Membrane potential and Ca concentration dependence on pressure and vasoactive agents in arterial smooth muscle: A model

Arteries are lined by endothelial cells and are wrapped by one or more layers of smooth muscle (SM) cells. There are electrical coupling and chemical signaling between SM cells and between SM cells and endothelial cells, and SM cells receive numerous neurotransmitter, endocrine, and paracrine signals that promote either contraction or relaxation. Independently of these signals, arterial SM cells respond autonomously to changes in sarcolemmal stretch caused by changes in intravascular pressure (McCarron et al., 1989). This phenomenon is called “myogenic reactivity.” It has an early phase called the “myogenic response” and a sustained phase called “myogenic tone.” The overall effect is to control luminal diameter in the face of changing luminal pressure. It is a vital background activity on top of which the many other stimuli have their effects.