Effects of D-glucuronolactone, L-gulonolactone and penitols on insulin secretion in dogs.

Abstract

Intravenous administration of 0.4g/kg D-glucuronolactone or L-gulonolactone, the precursors of xylitol in the glucuronate-xylulose cycle, produced only small increases in plasma insulin in dogs. The plasma insulin responses were far less than those following the equivalent dose of xylitol, and are presumably explained by the concomitant small rises in plasma glucose. Infusions of ribitol, L-arabitol or D-arabitol (2mg/kg. min) into the pancreatic artery of dogs did not produce any significant increases in plasma insulin concentration in the pancreatic vein, while xylitol and glucose infused in a similar manner always stimulated insulin release. These data appear against the direct involvement of the glucuronate-xylulose cycle or the pentose phosphate pathway in the mechanism of insulin secretion. The mechanism of strong insulin-releasing effect of xylitol in dogs remains unexplained.