Effects of Ouabain on Insulin Secretion in the Dog
The mechanism of the previously reported hypoglycemic effect of ouabain was studied in dogs. Ouabain (1.0 µg/kg/min infused intravenously for 60 minutes) combined with insulin or propranolol caused a greater and more prolonged decrease in blood glucose than either of the drugs administered separately. In intact dogs, ouabain changed significantly portohepatic venous differences in plasma glucose from +6.6 to -13.6 mg/100 ml and in K+ from -0.03 to -0.4 mEq/liter. In pancreatectomized animals, ouabain did not cause any significant decrease in peripheral glucose level, and the portohepatic differences in plasma glucose changed from +5.3 to +30.2 mg/100 ml and the differences in K+ from -0.01 to +0.2 mEq/liter. These changes, indicating an increased release of glucose and K+ by the liver in the pancreatectomized dog, were also observed in isolated rat liver perfused with ouabain 10-6M. Glucose uptake of the hindlimb increased significantly during the infusion of ouabain in normal dogs, but did not change in pancreatectomized dogs. Ouabain caused a significant increase in plasma insulin in portal blood (+155%). These results demonstrate that the observed metabolic effects of ouabain in the dog are mainly mediated by insulin and that ouabain increases the secretion of insulin in intact dogs.
- Received May 1, 1969.
- Accepted June 12, 1969.
- © 1969 American Heart Association, Inc.