NEUROMUSCULAR MECHANISMS OF PRIMARY PERISTALSIS

Primary peristalsis of the esophagus is initiated by the act of swallo wing, Control of the orderly contraction must take into account coordi nation of the activity in the esophageal body with the sphincters at e ither end, integration of activity between the striated and smooth mus cle portions of the esophagus, and the central and peripheral neural a nd muscular control mechanisms present. Peristalsis in the striated se ction is directed by sequential vagal excitation arising in a brainste m ''Central Program Generator.'' Peristalsis in the smooth muscle sect ion involves the interaction of central and peripheral neural mechanis ms and probably the interaction between these neural mechanisms and sm ooth muscle properties. Coordination of activity between the striated and smooth muscle portions has similar multifaceted neural and mechani cal components. In the smooth muscle, 2 main neural mechanisms, a chol inergic excitatory one and a nonadrenergic, noncholinergic (NANC) inhi bitory one interact together and with central and local influences to regulate the amplitude, velocity, and direction of propagation of the peristaltic contraction. (C) 1997 by Excerpta Medica, Inc.