Mechanoreceptors sensitive to flow at the gastroduodenal junction of the cat

Vagal afferent activity was recorded from the cervical vagus simultaneously with intraluminal pressure and flow rate at the proximal duodenum, in cats anesthetized with pentobarbital sodium. Thirty-seven mechanoreceptors that adapted slowly to maintained pressure changes were found to be sensitive to the flow of saline through the pylorus. The passage of liquid was associated with an increase of pressure equal to one-tenth of that necessary to trigger a response of the receptors during the distension of a small balloon. The frequency of discharge was increased by the passage of liquid for positive back pressures < or = 1.5 kPa but not when back pressure was negative. The relationship between the discharge of the receptor and the flow rate was complex and showed an hysteresis. We conclude that there exist slowly adapting mechanoreceptors sensitive to distension of the duodenum that can also sense the passage of liquid.