Effect of venous drainage to the vena cava and denervation on endocrine function of pancreatic segments in dogs.

IVGTTs and OGTTs (0.5 g/kg glucose) were performed in 36 normal dogs (group N) and one to two weeks postoperatively in 22 dogs after partial pancreatectomy [( ppx ] group I); nine dogs after ppx and pancreatic venous drainage to the inferior vena cava (group II); nine dogs after ppx and pancreatic denervation (group III); and in seven dogs after ppx , venous drainage to the vena cava, and denervation (group IV). Fasting glucose and insulin were in the same range in all dogs. In IVGTT peak insulin levels were diminished by ppx , but total insulin secretion was similar in all dogs. Systemic venous drainage and denervation had no effect on glucose tolerance, peak insulin, and total amount of insulin appearing in the peripheral circulation. In groups II and IV, there was a linear correlation between individual K values and the area under the insulin curve, whereas there was no such correlation in groups I and III. In OGTTs , glucose tolerance and the total amount of insulin were equal in groups I through IV but diminished compared to group N. Venous transposition resulted in an early increase of insulin secretion and a late insulin peak. Thus, glucose load and islet cell mass are the determinants of glucose tolerance and insulin secretion in this model. Neither drainage of the pancreatic blood to the vena cava nor denervation have measurable influence on magnitude and effectivity of fasting and stimulated insulin secretion.