Streptozotocin diabetes: a glucoreceptor dysfunction affecting D cells as well as B and A cells

Abstract

Somatostatin release from the isolated pancreas of 3 normal and 6 streptozotocin diabetic dogs has been measured in response to various stimuli to determine whether abnormalities in somatostatin release are present in the diabetic pancreas. Simultaneous measurement of glucagon secretion was also made. In the pancreas from normal dogs increases in perfusate glucose from 25 to 200 mg/100 ml induced a 2--3 fold increase in somatostatin release and a two thirds decrease in glucagon secretion. In contrast, in the diabetic pancreas glucose caused no change in the secretion of the two hormones. In the diabetic pancreas addition of insulin to the perfusate (25,000 microU/ml) for periods from 10 to 75 minutes aimed at restoring normal extracellular insulin levels in the islets failed to restore either somatostatin or glucagon secretion to normal. In contradistinction to the lack of effect of glucose, the somatostatin and glucagon responses to arginine (5 mmol/l), isoproterenol (2 ng/ml) and calcium (5 mmol/l) were normal in the diabetic pancreas. The data suggests the presence of a selective glucoreceptor abnormality of the D as well as of B and A cells in the streptozotocin diabetic dog.