Variation in contractile response characteristics of rabbit aorta strips with surface of drug entry.

Contractile responses of rabbit aorta strips to norepinephrine in the presence of cocaine, histamine and serotonin entering through the intima have been compared with those when these drugs enter via the adventitia. The responses to entry through the inner compared with the outer surface occur after a shorter latency, rise at a greater initial velocity and reach a high steady state. Differences persist after removal of the tunica adventitia. Responses of strips to intimal entry appear identical to those of the intact strip. These results suggest an asymmetry of vascular smooth muscle cell characteristics across the thickness of the tunica media of the rabbit thoracic aorta.