The mode of action of pilocarpine on outflow resistance in the eye of a primate (Cercopithecus ethiops).

Facility of outflow in the eye of the vervet monkey Cercopithecus ethiops was studied by constant-rate and by constant-pressure infusion. Facility increased greatly after the injection of 2 to 3 fig of pilocarpine into the anterior chamber or after the application of 0.2 to 0.3 ing. to the cornea. The effect on facility consisted of 2 components. One component was reversed in 3 to 5 minutes by 1 ing. per kilogram intravenous atropine, the time it took for the atropine to relax pilocarpine-incluced accommodation. The other component was reversed only slowly by intravenous or even intracameral atropine. The slowly reversed component toas thought to represent a pilocarpine action directly on the endothelial cells of the outflow system, possibly a histamine-like action on the endothelial wall of Schlemm's canal.