Oxidative Pathways in Pancreatic B Cells.

Abstract

1) A histochemical study has been conducted of the distribution of glucose-6-phosphate dehydrogenase (G-6-PD), triphosphopyridine nucleotide diaphorase (TPND), lactic dehydrogenase (LD), diphosphopyridine nucleotide diaphorase (DPND) and succinic dehydrogenase (SD) in the pancreas of the rabbit. G-6-PD was found principally in B cells and duct epithelium; LD in duct epithelium, acinar tissue and A cells. TPND was present throughout, with greatest activity in B cells and in duct epithelium and good activity in other areas. SD activity was present throughout the pancreas with greatest staining in B cells and duct epithelium. The reactive structures for SD seemed to be mitochondrial while the other enzymes apparently are mostly extramitochondrial. 2) These findings demonstrate that glucose metabolism in B cells is predominantly via the hexose monophosphate shunt, and indicates a role for it in insulin synthesis. A relationship between TPNH generation by this pathway and availability of reduced glutathione or of free SH groups in enzymes is considered as a possible mechanism controlling B cell insulin output.