Supersensitivity and endothelium dependency of histamine-induced relaxation in mesenteric arteries isolated from diabetic rats.

Diabetes mellitus is known to produce alterations in vascular reactivity. In the present study we have examined the effects of short-term diabetes on histamine-induced relaxation of isolated mesenteric arteries, and the role of the endothelial cell layer in this response. Removal of the endothelium completely abolished the histamine relaxation effect in both diabetic and age-matched control rats. In contrast, vessels isolated from streptozotocin-diabetic rats were supersensitive to histamine, and this relaxation was mediated only through the H1-receptors. The present findings suggest that histamine-induced relaxation of rat mesenteric arteries is dependent upon endothelial cell processes which are enhanced in arteries from STZ-diabetic rats.