Inhibition by atropine, phenoxybenzamine and propranolol of the autonomic nervous system of the domestic fowl.

Because of the paucity and inconsistency of information on blockage of the chicken autonomic nervous system for extended periods, the effects of atropine, phenoxybenzamine and propranolol in the anesthetized hen were examined. It was found that cholinergic blockade by atropine was very short lived. For effective (80%) parasympathetic blockage a priming dose of 0.25 mg./kg;, followed by an infusion at the rate of 17.5 microgram/kg./min., was required. Similarly, inhibition of the beta-sympathetic system required propranolol in a priming dose of 0.25 mg./kg. and an infusion of 5 microgram/kg./min. The alpha-sympathetic inhibitor, phenoxybenzamine, was effective when given as a single dose of 5 mg./kg. Using these levels of inhibitor it was possible to ensure blockade in all cases for periods of two hours or more.