Thoracic esophageal mechanoreceptors connected with fibers following sympathetic pathways.

The existence of splanchnic mechanoreceptors was demonstrated in the esophagus including the lower esophageal sphincter of anesthetized cats. For this purpose, unitary activities were recorded in T9, T10 and T11 spinal ganglia by means of extracellular glass microelectrodes. Two types of receptors were evidenced according to their location: the muscular and the serosal receptors. The muscular mechanoreceptors usually exhibited a weak spontaneous discharge (0.8-18 imp/sec) and adapted slowly to mechanical stimulations (distension, contraction, digital compression). The potent physiological stimulus resulted in distension for the receptors situated in the thoracic esophagus and contraction for the receptors located in the lower esophageal sphincter. The serosal mechanoreceptors were always silent and belonged to the rapidly adapting type. They responded mainly to touching the serous membrane, but strong distension or stretching was sometimes efficient. A comparison with the vagal receptors already described in this region is drawn, and the role of splanchnic mechanoreceptors is discussed.