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Abstract #6167 Published in IGR 2-2
Low doses of pilocarpine do not significantly increase outflow facility in the cynomolgus monkey
Kiland JA; Hubbard WC; Kaufman PLExperimental Eye Research 2000; 70: 603-609
Low doses (10(-9)-10(-6) M) of pilocarpine reportedly increase outflow facility in the organ-cultured human eye, suggesting a direct action on the trabecular meshwork. M3 muscarinic receptors have been found in both cultured human trabecular meshwork cells and tissue. The authors determined whether low pilo doses would increase outflow facility in the living monkey. The anterior chambers of both eyes of 17 pentobarbital anesthetized cynomolgus monkeys were cannulated and outflow facility measured bilaterally by two-level constant pressure perfusion after an initial 2 ml exchange with Barany's perfusand containing 24.5 μm phenylephrine (PE). Two subsequent exchanges were performed with one eye receiving Barany's + PE + 10(-10)-10(-4) M pilocarpine and the contralateral eye receiving only Barany's + PE. Outflow facility was measured for 35-40 minutes following each exchange. Accommodation and pupil diameter were measured before each exchange and approximately every ten minutes during facility measurements. Outflow facility was significantly increased by 154 and 313% in eyes treated with 10(-5) M and 10(-4) M pilocarpine, respectively, related to contralateral controls. Accommodation and miosis also were induced only at 10(-5) M (accommodation, 3.3 ± 1.6 D, NS; miosis, -4.1 ± 0.5 mm, p < or = 0.001) and 10(-4) M (accommodation, 10.6 ± 0.0 D, p < or = 0.02; miosis, -3.4 ± 1.0 mm, p < or = 0.025) pilocarpine. The authors conclude that low anterior chamber doses of pilocarpine do not increase outflow facility in the living monkey as reported in the organ-cultured human eye, nor do they induce miosis or accommodation. All three parameters respond to pilocarpine at similar doses, and there is no functional evidence of a meaningful outflow facility-relevant pilocarpine effect on the trabecular meshwork at doses lower than those which affect the ciliary muscle.
Dr. J.A. Kiland, Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA
Classification:
11.2 Cholinergic drugs (Part of: 11 Medical treatment)
