OCULAR FLUOROPHOTOMETRY IN STREPTOZOTOCIN DIABETES-MELLITUS IN THE RAT - EFFECT OF PANCREATIC-ISLET ISOGRAFTS

Abstract

Fluorophotometry was used to evaluate the integrity of the blood-ocular barriers to fluorescein in experimental diabetes mellitus in rats. This technique allowed quantitation of ocular fluorescein concentrations following i.v. injection. Streptozotocin-induced diabetes resulted in an increased fluorescein accumulation in the anterior chamber (1.52 .+-. 0.17 .mu.g/ml, mean .+-. SEM) and vitreous (0.82 .+-. 0.11) over baseline nondiabetic levels (0.68 .+-. 0.80 and 0.40 .+-. 0.03, respectively). Fluorophotometry was repeated at 5, 13, and 20 days following portal vein pancreatic islet transplantation. At 5 days anterior chamber (1.40 .+-. 0.17) and vitreous (0.61 .+-. 0.08) fluorescein concentrations remained elevated. At 13 and 20 days following islet transplantation, ocular fluorescein concentrations were identical to levels observed prior to the induction of diabetes. I.v. glucose (0.5 gm/kg) tolerance testing was performed 5 and 13 days following transplantation. The glucose responses to the tolerance test were normal and similar at both times. At 5 days the insulin response was abnormal with a decreased initial peak and an absent 2nd peak. At 13 days there was a normal biphasic insulin response. In experimental diabetes mellitus ocular vascular permeability was more closely correlated with insulin than blood glucose abnormalities.