Direct vasodilator activity of atropine in the rat perfused hindlimb preparation

1. The autoperfused hindlimb technique in the rat was used to determine the effects of atropine upon the peripheral vasculature. 2. Injection of atropine (0.1-0.8 mumoles) into the hindlimb perfusion circuit resulted in a dose-dependent decrease in perfusion pressure which was immediate in onset and always preceded systemic pressure changes. The duration of vasodilation lengthened with increasing doses of atropine and ranged from 1.5 to 9 min. 3. During atropine-induced vasodilation, challenging doses of acetylcholine did not alter the perfusion pressure. 4. These experiments suggest that atropine is capable of direct vasodilator activity upon the peripheral vasculature in which a muscarinic mechanism appears unlikely.