Effect of Anomers of D-glucose on Alloxan Inhibition of Insulin Release in Isolated Perifused Pancreatic Islets

Abstract

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.

Alloxan: history and mechanism of action

“…4. Only D-glucose, with a preference for the a-anomer when compared with the fl-anomer [43,47,55,56,58,59] and D-mannose protect glucose-induced insulin secretion [29,59] and pancreatic B cell glucokinase [43,47] against inhibition by alloxan; while sugars like Dfructose, D-galactose, and L-glucose are ineffective [43,59]. High alloxan concentrations can overcome the glucose protection of the pancreatic islets [60] and of the glucokinase against alloxan action (S.Lenzen, unpublished observation).…”

Short-Term Memory: the "Storage" Component of Human Brain Responses Predicts Recall

“…The percentage of correct recalls from 52 subjects (29 female and 23 male college students) are given in z-score units (Fig. 1D) (12).…”

“…The light intensity was approximately 2.8 log units above threshold for character recognition. 12 lifetime of cells cultured from human embryos has been reported and has been considered to be a factor responsible for limited life-span and aging of organisms (6).…”

Effects of alloxan on glucose-stimulated insulin secretion, glucose metabolism, and cyclic adenosine 3?, 5?-monophosphate levels in rat isolated islets of Langerhans

“…Research was spurred on by the observation that protection showed relative anomeric specificity for both a-D-glucose and 3-0-methyl-a-D-glucose. It was speculated that alloxan might prove to be a useful probe in determining the characteristics of the glucoreceptor system which is said to exist in islet tissue [9][10][11].…”