Vascular Reactions in Chronically Inflamed Skin

Abstract

Part I of these studies on vascular reactions in chronically inflamed skin dealt with mechanical cutaneous stimulation and the inhibition of white dermographism.¹This part will consider the action of epinephrine and phentolamine (Regitine), and the action of acetylcholine and methacholine (Mecholyl), together with a discussion of the "delayed blanch" phenomenon. Action of Epinephrine and an Inhibitor, Phentolamine The most powerful physiologic agents for constricting the blood vessels of the skin are epinephrine and arterenol (norepinephrine), both of which are elaborated by the adrenal medulla and at the ends of postganglionic sympathetic fibers. Arterenol probably is the major adrenergic mediator at the postganglionic neuroeffector junctions, whereas epinephrine is the predominant sympathomimetic amine released by the adrenal medulla. Epinephrine is thought to be formed by the methylation of arterenol, the methyl group coming from such methyl donors as methionine.² Arterenol and epinephrine act directly on