Modulation of hormone secretion by functional electrical stimulation of the intact and incompletely dysfunctional dog pancreas

Abstract

The purpose of the present study was to modulate the secretion of insulin and glucagon in Beagle dogs by stimulation of nerves innervating the intact and partly dysfunctional pancreas. Three 33-electrode spiral cuffs were implanted on the vagus, splanchnic and pancreatic nerves in each of two animals. Partial dysfunction of the pancreas was induced with alloxan. The nerves were stimulated using rectangular, charge-balanced, biphasic, and constant current pulses (200 μs, 1 mA, 20 Hz, with a 100-μs delay between biphasic phases). Blood samples from the femoral artery were drawn before the experiment, at the beginning of stimulation, after 5 min of stimulation, and 5 min after the end of stimulation. Radioimmunoassay data showed that in the intact pancreas stimulation of the vagal nerve increased insulin (+99.2 μU/ml) and glucagon (+18.7 pg/ml) secretion and decreased C-peptide secretion (-0.15 ng/ml). Splanchnic nerve stimulation increased insulin (+1.7 μU/ml), C-peptide (+0.01 ng/ml), and glucagon (+50 pg/ml) secretion, whereas pancreatic nerve stimulation did not cause a marked change in any of the three hormones. In the partly dysfunctional pancreas, vagus nerve stimulation increased insulin (+15.5 μU/ml), glucagon (+11 pg/ml), and C-peptide (+0.03 ng/ml) secretion. Splanchnic nerve stimulation reduced insulin secretion (-2.5 μU/ml) and increased glucagon (+58.7 pg/ml) and C-peptide (+0.39 ng/ml) secretion, and pancreatic nerve stimulation increased insulin (+0.2 μU/ml), glucagon (+5.2 pg/ml), and C-peptide (+0.08 ng/ml) secretion. It was concluded that vagal nerve stimulation can significantly increase insulin secretion for a prolonged period of time in intact and in partly dysfunctional pancreas.