Vascular reactions in chronically inflamed skin. III. Action of histamine, the histamine releaser 48-80, and monoethanolamine nicotinate (nicamin).

Parts I and II of these studies on vascular reactions in chronically inflamed skin dealt with mechanical cutaneous stimulation, inhibition of white dermographism, and the action of epinephrine, phentolamine (Regitine), acetylcholine, and methacholine (Mecholyl). 1,2 This third and final part will consider the action of histamine and the histamine releaser called "48-80" (condensation product of p -methoxyphenylethyl-methylamine and formaldehyde) and the action of monoethanolamine nicotinate (Nicamin), an organic salt of nicotinic acid. Action of Histamine and the Histamine Releaser 48-80 Histamine, when introduced into the skin, produces the well-known triple response. The three components of this response are local reddening from local vasodilatation of minute vessels, the widespread dilatation of neighboring arterioles caused by a local neural response (the axon reflex), and the local enlarging wheal produced by increased vascular permeability. This reaction to histamine is similar to that seen after mechanical stroking