Direct effect of phenylethylamine upon isolated rat aortic strip.

Phenylethylamine (PEA) has been implicated in a number of central and peripheral nervous system disorders. Its possible mechanisms of action include stimulation via catecholamine release and direct stimulation by PEA. We have examined the effects of PEA on isolated vascular smooth muscle (VSM) to further explore the mechanism by which PEA produces contraction in this tissue. Helical strips of rat aorta were suspended in a muscle bath. Smooth muscle contractions were recorded via force transducer. PEA elicited a concentration dependent contraction from these strips with a threshold near 10(-6) M and a maximum response at 5 X 10(-3) M. Pretreatment of rats with reserpine dramatically reduced the norepinephrine (NE) content of kidney, heart and spleen of these animals but did not prevent the action of PEA on VSM. The presence of phentolamine (10(-4) M) completely blocked the strip response to PEA. The presence of propranolol (10(-7) or 10(-4) M) altered but did not block the VSM response to PEA. These results argue that the effects of PEA upon the aortic strip preparation involve a direct action of this amine upon VSM.