EARLY EFFECTS OF EPINEPHRINE ON AQUEOUS HUMOR DYNAMICS IN VERVET MONKEYS (CERCOPITHECUS ETHIIOPS)

The early effects of topical administration of 2% l-epinephrine bitartrate on the dynamics of aqueous humor were studied in 15 vervet monkeys. In 10 animals the eye pressure was not interfered with; in 5 the eye pressure was stabilized at about 22 mmHg using reservoirs. [131I]Albumin was used to determine the net formation of aqueous humor in one eye; [125I]albumin was used in the other eye. The average net rate of aqueous formation in the treated eyes and that in the controls were the same 1·61 ± 0·14 μl/min. The rate of flow into the general circulation was 0·34 ± 0·10 μl/min less in the treated eyes than in the controls. The uveo-scleral drainage was enhanced in the treated eyes. The facility of outflow was 0·35 ± 0·07 μl. min-1. mmHg-1 higher in the treated eyes than in the controls. There was little effect on pseudofacility, probably due to a high arterial blood pressure caused by absorption of the drug. Epinephrine tended to raise the recipient venous pressure. It is suggested that epinephrine has a facility reducing effect that is due to relaxation of the ciliary muscle and a facility increasing effect that may be due to some change in the endothelium of the canal of Schlemm. Since epinephrine has several antagonistic effects the effect on the intraocular pressure can be expected to vary even qualitatively. © 1969 Academic Press Inc. (London) Ltd. All rights reserved.