Microvascular Protein Efflux: Interaction of Histamine and H 1 Receptors 1

Abstract

Abstract

The effects of H₁ and H₂ receptor antagonists on histamine-induced increase in microvascular protein transport was examined in the dog forelimb and horse digit. Local intraarterial infusion of histamine (4 μg/min of the base) produces marked increases in lymph flow, lymph protein concentration, and the estimated permeability-surface area (PS) ratio in both the limb and digit (3). These increases were completely prevented in the horse digit by local administration of the H₁ antagonist, tripelennamine, and in the dog forelimb by the H₁ antagonist, diphenhydramine. In contrast, cimetidine or metiamide, H₂ antagonists, failed to greatly alter histamine-induced increases in lymph flow, lymph protein concentration, and PS ratios in the horse digit. Metiamide, except at an extremely high dose (1 mg/min), also failed to alter the histamine-induced increases in canine forelimb lymph flow, lymph protein concentration, and PS ratio. It is concluded that local infusion of histamine to the skin vasculature increases protein transport predominantly via interaction with an H₁ receptor.