Physiologic specialization at esophagogastric junction in three species.

CHRISTENSEN, JAMES, JEFFREY L. CONKLIN, AND BARRY W. FREEMAN. Physiologic specialization at esophagogastric junction in three species. Am. J. Physiol. 225(6): 1265-1270. 1973.-In opossums, cats, and monkeys comparisons were made of length-resting tension relationships and responses to low-frequency electrical field stimulation among serial 2 mm-wide strips cut transversely from the esophagogastric junction and adjacent stomach and esophageal body. Three regions could be distinguished on the basis of the nature of the response to field stimulation. Strips from the stomach contracted during stimulation; those from the esophageal body contracted briefly after the end of the stimulus; strips from the esophagogastric junction relaxed during stimulation. Transitional areas lay between the three regions showing these tetrodotoxin-sensitive responses. The length-resting tension slopes of strips from the esophagogastric junction were steeper than those of strips from the stomach and esophageal body. The strips which relaxed with field stimulation included those with the steepest slopes of the length-resting tension relationship. Slopes of length-resting tension were poorly correlated with muscle mass. In all three species, intrinsic specialization occurs at the esophagogastric junction in the nature of the innervation and in the mechanical properties of the inner muscle layer.