Topical substance P and corneal epithelial wound closure in the rabbit.

Purpose: The authors determined the effect of topically applied substance P (SP) on the rate of corneal epithelial wound closure in the rabbit.

Methods: Uniform circular lesions, 6.5 mm in diameter, were made bilaterally in the corneal epithelium of 24 rabbits using N-heptanol. Substance P was applied repeatedly to one eye, and the SP1-7 fragment was applied to the contralateral (control) eye until wound closure was obtained. Three concentrations of peptide solution (5 x 10(-5) M, 5 x 10(-4) M, and 5 x 10(-3) M) were tested in separate groups of eight animals each. An additional eight animals received topical applications (5 x 10(-7) M) of the neurokinin-1 (NK1)-specific SP receptor antagonist CP-99,994-01 or its ineffective enantiomer CP-100,263-01. The mean rates of wound healing for each group of experimental and control eyes were determined by linear regression and analyzed by analysis of variance.

Results: There were no statistically significant differences in the mean rates of wound closure (range, 0.083 to 0.106 mm/hour) between experimental- and control-treated corneas for any of the four groups tested.

Conclusions: The topical application of SP or its NK1 receptor antagonist has no significant effect on the rate of corneal epithelial wound closure in the rabbit.