Pharmacodynamic study of the capillaries of normal and allergic (atopic) subjects.

Using the capillary resistance test as a method to study the cutaneous microvessels, a number of capillary active agents were investigated by applying them percutaneously in hydrophylic ointment base to manifestly allergic and definitely non-allergic volunteers. While the catecholamines and heparin increased capillary resistance in both allergic and non-allergic groups, metacholine, serotonin, the somatotropic hormone and nitroglycerin either did not change or decreased capillary resistance in the normal group and invariably increased it in the members of the allergic group. The effects of catecholamines were, completely or partially, blocked in the normal group by pretreatment of the skin with dibenzyline or propranolol. In the members of the allergic group, blockade was often weak or absent indicating some derangement in the adrenergic receptors. The significance of the findings is discussed.