Variability of gastric secretory response to insulin hypoglycemia in fistulous beagle dogs

¹ Department of Neurosurgery and Physiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania

The gastric secretory response to a uniform dosage of insulin (1.5 U/kg) was studied in seven beagle dogs with a Thomas fistula. The resting secretion was mucoid in character and alkaline. Variations in acid output after insulin stimulation showed a parallel reduction of volume and concentration, indicating that these changes were not the result of incomplete sample collections. In 43 of 50 insulin experiments, maximum gastric output occurred between 30 and 60 min after insulin administration. Thirty minutes after insulin there was a mean 42.5% reduction of blood glucose below fasting values, although the exact time of the nadir could not be determined. Different experiments in the same animal showed no statistical correlation between blood glucose levels and acid concentration or output. A late phase of gastric secretion was defined as an increase in acid output of 0.5 mEq/30 min which occurred at least 120 min after insulin administration. Late phases were seen in eight experiments, seven of which occurred in two animals. In the remainder of the experiments, initial maximum acid output was reached within 60 min and the basal state was reached within 180–240 min, when the blood glucose values had returned to fasting levels.