substance-p--arg(1)-pro(2)-trp(7-9)-leu(11)- and Miosis

This study was undertaken to characterize the mechanism of ocular irritation to YAG laser capsulotomy in rabbits. The blocking agents were administered intravitreally. (D-Arg1,D-Pro2,D-Trp7,9)-SP, a substance P antagonist, tended to reduce miosis but had no effect on intraocular pressure (IOP). It had less effect on miosis than (D-Arg1,D-Pro2,D-Trp7,9,Leu11)-SP another SP antagonist. Met-enkephalin and tetracaine had no effect on miosis or the increase in IOP after YAG laser capsulotomy, whereas tetrodotoxin reduced miosis, but had no clear-cut effect on IOP, or the increase in aqueous humor protein concentration. This indicates an involvement of sensory neurons with release of SP or a closely related peptide in the miotic component part while the increase in IOP and the barrier breakdown probably are dependent mainly on a release of prostaglandins.

Topics: Animals; Enkephalin, Methionine; Eye Proteins; Female; Intraocular Pressure; Laser Therapy; Lens Capsule, Crystalline; Lens, Crystalline; Male; Miosis; Neural Conduction; Rabbits; Recombinant Proteins; Substance P; Tetracaine; Tetrodotoxin; Time Factors