Postganglionic Site of Action of Nicotine with Special Reference to its Direct Action on Blood Vessels

Abstract

In the Laewen-Trendelenburg prepn., which is essentially an isolated vascular bed, nicotine induces marked vasoconstriction. Resection of both sympathetic chains and of all spinal nerves does not alter the action of nicotine. Tetraethylammonium ion, capable of blocking the action of the "nicotinic-stimulating" substances upon ganglion cells, curare, capable of paralyzing postganglionic fibers, and Dibenamine capable of blocking the same fibers, do not abolish the vasoconstrictor action of nicotine. Serial sections of the vessels of the frog''s hind legs have shown the absence of ganglion cells. It appears, therefore, that in the Laewen-Trendelenburg preparation the site of action of nicotine is peripheral to the postganglionic fibers, possibly directly on the blood vessels. In the intact animal, it may be assumed that in addition to its known sites of action on ganglion cells, and adrenal medulla, nicotine may also act directly on the neuroeffector cells of the blood vessels.