Control of A and B cells in vivo by sympathetic nervous input and selective hyper or hypoglycemia in dog pancreas.

An extra-corporeal blood circuit was established between the cranial pancreatico-duodenal vein and the portal vein in the dog. Timed measurements of flow, hematocrit, insulin and glucagon concentrations in this circuit were made in order to calculate the secretion rates of insulin and glucagon. The plasma glucose concentration in the pancreatico-duodenal vein was monitored at steady state from 50 to 330 mg/100 ml for periods of 70 min by infusing a saline solution or glucose into the cranio-pancreatico-duodenal artery. No change in peripheral glucose concentrations was detected. 1. When glucose concentration in the PD vein was lowered from 100 mg/100 ml to about 50 mg/100 ml, the basal insulin secretion rate was not modified. When the glucose concentration was increased from 100 mg/100 ml to about 300 mg/100 ml, the insulin secretion rate increased linearly over the range of concentrations tested. 2. Glucagon secretion rate was unmodified throughout the range of glycemia tested. Whereas net pancreatic glucagon secretion rate was not reduced by selective pancreatic hyperglycemia, it was reduced by systemic hyperglycemia at about the same concentration. 3. In atropinized pancreas, low frequency (2 Hz) electrical stimulation of the distal end of the ligated mixed pancreatic nerve caused a mean decrease of 44% in the secretion rate of insulin, and a mean increase of 42% in the secretion rate of glucagon at all PD vein glucose concentrations studied. 4. It can be concluded, therefore, that the sympathetic nervous input at physiological frequencies controls the moment-to-moment secretory activity of the A and B cells of the pancreas independently of the concentrations of glucose.