Abstract
Octopamine (p-hydroxy-β-phenylethanolamine) was first extracted from the salivary glands of octopus (1). Later it was found in human and animal urine (2). More recently, it has been isolated and identified from extracts of juice and leaves of Meyer lemon (3). The conversion of tyramine to octopamine has been shown in vitro by a broken cell preparatoin (4) and by isolated organs (5). Octopamine has also been found in the salivary glands, heart and spleen of rats after tyramine administration (6-9). Lemberger and associates have presented evidence that an appreciable portion of tyramine is converted to octopamine in vitro (10). Octopamine is capable of replacing noradrenaline in its storage sites and the octopamine is released by sympathetic nerve stimulation. Thus, octopamine is proposed as a false neurochemical transmitter (8, 9). Since Lands and Grant (11) first evaluated a pressor action of octopamine, several reports have appeared regarding the pharmacological action of octopamine, and this compound has long been used as a pressor agent in hypotensive patients. However, no detailed report on the pharmacological effects of octopamine in reference to the biochemical conversion to noradrenaline is available. In the present experiments it was attempted to correlate sympathomimetic effects of octopamine with the endogenous noradrenaline by means of pharmacological, biochemical and histochemical techniques.
