Histamine release by sugar polymers in the rat.

Histamine release into the peritoneal cavity of rats following intraperitoneal injections of sugar polymers such as dextran or dextrin was potentiated by insulin, even when the hormone was given simultaneously with the polymer and the blood sugar level was unchanged. Hypoglycaemia is therefore not the factor responsible for the potentiation. A direct effect of insulin on peritoneal mast cells in vivo is suggested, particularly as the potentiation by insulin occurred in diabetic rats and this was inhibited by disodium cromoglycate.