Rat Serum “Bound” Insulin: In Vivo Biologic Effects in Rats

Abstract

Intravenous administration of partially purified preparations of rat serum “bound” insulin into hypophysectomized rats, produced hypoglycemia and stimulated the incorporation of glucose carbon into the glycogen of muscle and adipose tissue and into the fat of the adipose tissue of these animals. Intraperitoneal injections of rat “bound” insulin into intact, fed rats also stimulated the incorporation of glucose carbon into the glycogen of muscle and adipose tissue and into the fat of the adipose tissue. Rat “bound” insulin, like human, was less effective in stimulating glycogen synthesis than fat synthesis on adipose tissue, as compared with crystalline insulin. The in vivo biologic effects of rat “bound” insulin in rats correspond to those produced by human “bound” insulin or crystalline bovine insulin. The properties of rat “bound” insulin appear to be similar to those of human “bound” insulin. Rat “bound” insulin, like human, was obtained from sera by resin adsorption and elution, was biologically active in vivo, inactive on isolated hemidiaphragm, unless adipose tissue extract (ATE) was added into the incubating medium, and unreactive with anti-insulin antisera.