Sodium pentobarbital depression of histamine- or insulin-stimulated gastric secretion

Abstract

Secretion of H, Cl, Na, K, and pepsin, stimulated by infusion of histamine (1 mg base/hr) and insulin (10 units), was studied in 5 dogs with gastric cannulas during Nembutal anesthesia (ca. 28 mg/kg) and also in the unanesthetized state. Histamine-stimulated water secretion was inhibited 38% by Nembutal which produced suppression of volume out not of H+ or Cl concentrations and left the hyperosmolality of gastric juice relative to plasma (1.03) unchanged. These findings were interpreted as representing a reduction in the number of actively responding parietal cells, but not in the responsiveness of each cell, possibly by a reduction in effective mucosal blood flow. Despite an equivalent degree of hypoglycemia, the gastric juice volume response to insulin was much more strongly (77%) inhibited, and not only volume but also the concentration of H+ was depressed. Pepsin secretion was inhibited similarly by Nembutal regardless of the stimulus. These findings suggest a more direct and probable vagolytic effect of Nembutal on the hypoglycemic stimulus, to which must be added the direct electrolyte-inhibiting effect of insulin and the nonspecific Nembutal effect typified by the histamine results.