[Effects of endothelin-1 on choroidal vessels--1. Study with the scleral window technique]

The effects of topical administration of endothelin-1 (ET-1), a potent and long-acting vasoconstrictive peptide, on choroidal vessels were studied in albino rabbits. In enucleated eyes that were divided and the retinas removed, topical instillation of ET-1 at 5 x 10(-5)M induced remarkable constriction of choroidal arteries and veins. In vivo, the scleral window technique and microcinematography were used to study the effects of ET-1 on the choroidal arteries. The same field was recorded before, and 15 and 30 minutes after, instillation of 2 microliters of ET-1 at 5 x 10(-5)M every 5 minutes. Topical application of ET-1 did not cause any statistically significant change in caliber of the choroidal arteries either in the untreated group or in the ganglionectomy group (superior cervical sympathetic ganglions were removed and choroidal arteries were dilated). These results suggest that ET-1 acts in choroidal arteries from the retinal side in vitro but does not act from the scleral side in vivo.