Pituitary Growth Hormone and the Question of Pancreatic Secretion of Glucagon

Experiments are presented in which normal dogs were injected with a highly purified growth hormone preparation. One hour later blood samples were drawn simultaneously from the pancreatico-duodenal and jugular veins. The ‘central’ and ‘peripheral’ blood samples were injected into depancreatized dogs. While the injection of ‘peripheral’ blood produced no appreciable change in the blood sugar level of the diabetic recipient, the ‘central’ blood caused a definite but transient rise in blood sugar. The rise could be prevented by treating the recipient diabetic animal with the adrenergic blocking agent dihydroergotamine. It has been concluded that the hyperglycemic factor present in the blood of the pancreatico-duodenal vein after injection of growth hormone preparations is not identical with glucagon-Lilly, the effect of which is not influenced by dihydroergotamine. In two experiments in which completely depancreatized, instead of intact, dogs were used as donors the administration of growth hormone produced the characteristic hyperglycemic response when ‘central’ blood samples were injected into other depancreatized dogs. These findings cast doubt on the pancreatic origin of the hyperglycemic material and add interest to the search for its source and nature. Further experiments using depancreatized dogs are in progress.