EFFECTS OF HEXOSES AND THEIR DERIVATIVES ON GLUCAGON-SECRETION FROM ISOLATED-PERFUSED RAT PANCREAS

Although it has been firmly established that D-glucose inhibits glucag on secretion from pancreatic A cells, the regulatory mechanism of gluc agon secretion by D-glucose has not been elucidated. To study this reg ulatory mechanism by D-glucose, the effects of hexoses and their deriv atives on glucagon secretion from the A cells of isolated perfused rat pancreas were investigated. When these cells were perfused with D-glu cose, D-fructose, D-sorbitol, D-galactose, Z-deoxy-D-glucose, D-glucon ic acid sodium salt and D-glucosamine HCl salt, glucagon secretion was significantly inhibited. None of the hexoses or their derivatives tes ted were found to stimulate glucagon secretion. The effects of these s ugars on glucagon secretion were independent of their metabolism in th e cells. From the findings that the sugars both metaboliized and unmet abolized in the cells demonstrated comparable inhibition of glucagon s ecretion from the isolated perfused rat pancreas, it is speculated tha t the recognition system for these sugars may be probably present on t he A cell membrane and responsible for mediating these inhibitory effe cts of glucagon secretion.