THE PHARMACOLOGICAL ACTION OF CHOLINERGIC SUBSTANCES ON NEW CORNEAL BLOOD VESSELS IN RATS

Abstract

This study aimed to evaluate the existence of muscarinic receptors in the new corneal blood vessels, experimentally induced with ketamine in rat pups. The experimental model of neovascularization was performed on 15-day-old Wistar rats, in which 5 intraperitoneal injections of ketamine were administered at a dose of 150 mg/kg body weight at 5-day intervals. Examination of the reactivity of new corneal blood vessels was performed on day 45 of life. Each eye that developed neovascularization was evaluated with a Nikon stereomicroscope, coupled to a Mshot video camera, and the total magnification of the system was 400X. The vascular diameter was measured at a chosen point, the same point /points for each recording made to that eye, and the acquisition of images was performed at set time intervals, every 60 seconds for each eye to be examined, throughout the recording period. The parameters under investigation were the variations of the vascular diameter, and the processing of the obtained data was performed with the help of Microsoft Office Excel. Our results suggest that muscarinic receptors are present in the new corneal blood vessels because the administration of conjunctival instillations of acetylcholine caused statistically significant vasodilation, while atropine, a blocker of muscarinic receptors, antagonized this effect.