Alloxan infused into the isolated perfused rat pancreas caused transient insulin secretion and permanent suppression of amino-acid-stimulated glucagon release. Alloxan poisoning also prevented subsequent induction of glucose-mediated insulin release and also prevented the inhibition of glucagon release by glucose. Glucose or 3-0-methylglucose infused simultaneously with alloxan protected the α-and β-cell, allowing subsequent glucose inhibition of glucagon secretion and stimulation of insulin release. The above alloxan effects were dose-related, the α-cell being one fourth as sensitive to alloxan as the β-cell.
The data indicate-that (1) alloxan and glucose suppression of amino-acid-stimulated glucagon secretion is independent of concomitant insulin secretion; (2) alloxan, like glucose, affects α-and β-cells directly, stimulating the β-cell and inhibiting the α-cell; and (3) alloxan acts on a glucoreceptor system with comparable physicochemlcal characteristics common to both cell types.
