Regulation of uveal and retinal blood flow in STZ-diabetic and non-diabetic rats; involvement of nitric oxide

PURPOSE. In experimental and human diabetes mellitus evidence for an impaired function of the vascular endothelial cells has been found. The purpose of the present experiments was to measure uveal and retinal blood flow and vascular resistance at an early stage of experimental diabetes mellitus and to evaluate the effects of acetylcholine and L-arginine in control and L-NAME-pretreated animals. METHOD. The radioactively labelled microsphere method was applied to normal Sprague-Dawley rats and rats with STZ-induced diabetes of three weeks duration. RESULTS. In the present study, similar blood flow and vascular resistance were observed in the uvea of normal and STZ-diabetic rats. Evidence for a basal vasodilating NO-tone was found both in the uvea and in the retina of both groups. In the normal rats as well as in the diabetic animals, acetylcholine induced choroidal vasodilation. Local blood flow increased from 54 ± 17 to 142 ± 32 mg × min -1 in normal rats and from 57 ± 18 to 112 ± 23 mg × min -1 in diabet...