Effect of anomers of D-glucose on alloxan inhibition of insulin release in isolated perifused pancreatic islets.

The in vitro inhibition of insulin released by alloxan (20 mg/100 ml) in collagenase isolated rat islets is preferentially prevented by alpha D-glucose at a concentration of 1.0 mg/ml, while at a higher anomer concentration (1.5 mg/ml) both alpha and beta D-glucose provide equal protection. The ability of alpha D-glucose compared with beta D-glucose to stimulate insulin release, in vitro, showed a similar dose-related response, as observed in the alloxan protective studies. Although, both alpha and beta D-glucose compete with mutorated D-glucose for transport into islet cells, neither anomer produced a significantly different degree of inhibition in the transport process. The shared alpha stereospecificity for D-glucose in protection against alloxan and in stimulating insulin secretion in these in vitro studies, suggest a common site of interaction which may involve the beta-cell membrane.