Increased histamine in plasma and tissues in diabetic rats.

In view of the previous observation that the histamine content of the aorta in rats with streptozotocin-induced diabetes mellitus is increased significantly over that in controls, we have investigated the effect of experimental diabetes on the histamine content of the plasma, the aorta, the kidney, the heart, the lung and the brain. Our data show that the histamine content of the plasma, the aorta, the heart, the kidney, the lung and the brain is significantly greater in diabetic rats than that found in controls. This increase in plasma and tissue histamine content may contribute to the increase in capillary and endothelial permeability known to occur in diabetes, and may have a role to play in the pathogenesis of diabetic micro- and macroangiopathy.