Gastric pressures in pigs during eating and drinking

Pressures were measured with miniature transducers positioned within the gastric lumen of six young pigs, 20-40 kg, eating and drinking operantly. The pigs were free to move about, lie down, sleep, eat, and drink without disturbance. 1) At the end of 4-5-h fasts (with no drinking), mean pressure within the stomach was 12 cm H2O, then rose during 22-min eating bouts to 22 cm H2O. 2) At the end of 16-18-h periods of food and water deprivation, intragastric pressure was 9 cm H2O. When water was drunk, pressures rose only to 13 cm H2O, then fell. When food was then eaten, pressures rose during 29-min meals to 22 cm H2O. 3) During spontaneous eating and drinking, intermeal pressures were maintained at 22-25 cm H2O, fell by 4-5 cm H2O just as eating or drinking began, then rose slowly, but only to the preingestive pressure level by the end of the bout. These results indicate that during spontaneous eating and drinking, gastric distention per se plays a smaller direct role in causing satiety than it does during meals ingested after a period of food deprivation.