Peripheral component in reserpine induced miosis.

Reserpine, on systemic administration (1) as well as after intracerebroventricular injection (2), exerts parasympathomimetic effects such as miosis, salivation, and diarrhoea. These effects have been attributed to increased central parasympathetic activity since reserpine increases the acetylcholine contents of the hy pothalamus (3). A direct parasympathomimetic action of reserpine has been excluded by Beckman (4). However these observations do not exclude the possibility of a peripheral component of action in the reserpine induced miosis. Therefore, it was planned to study the effect of topical application of reserpine on the pu pillary size in rabbits. Four adult albino rabbits of either sex weighing from 1.0 to 1.4 kg were employed in the present study. The drug was applied topically as 0.10 o ointment in one eye while in the other eye (control eye) only vaseline was applied. The ointment was applied daily for seven days and the pupillary size was measured each day before the application of the drug. Pupillary size was measured according to the method of Chen and Way (5) suitably modified by providing gradually increasing sized apertures instead of the black dots. The pupil was continously observed for one minute through the appropriate aperture of the pupillo meter kept at a constant distance from the rabbit eye and the diameter noted.