
Phalloidin Inhibits Epinephrine's and Cytochalasin B's Facilitation of Aqueous Outflow
James C. Robinson, MD;
Paul L. Kaufman, MD
Arch Ophthalmol. 1994;112(12):1610-1613.
Abstract
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Objective To determine whether phalloidin, a fungal peptide that inhibits actin filament depolymerization, could inhibit the ability of cytochalasin B and epinephrine to increase the facility of aqueous outflow in the eyes of living cynomolgus monkeys.
Methods Outflow facility was determined by two-level constant-pressure perfusion of the anterior chamber. After measurement of baseline facility in both eyes, one eye of each animal received intracameral phalloidin (1.3, 13, or 130 µmol/L); the opposite eye received vehicle. Both eyes then received either epinephrine (0.3 mmol/L) or cytochalasin B (0.2 mmol/L), and facility was again measured.
Results Cytochalasin B and epinephrine increased facility by 120% to 190% and 100% to 180%, respectively (uncorrected for 15% resistance washout caused by perfusion itself). Phalloidin itself (13 or 130 µmol/L) did not affect facility, but it inhibited up to 50% of the facility-increasing effect of cytochalasin B and epinephrine.
Conclusions We conclude that (1) the aqueous humor outflow facilitating effects of cytochalasin B or epinephrine depend in some manner on depolymerization of actin filaments within trabecular meshwork cells, and (2) actin filaments may help regulate aqueous outflow.
Author Affiliations
From the Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison. The authors have no proprietary or commercial interest related to the subject matter in the manuscript.
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