It is the aim of this project to study the regulation of fatty acid desaturation in blood platelets from normal and diabetic aaimals and to attempt to relate this regulation to the abnormal platelet function observed in diabetes. That this increased platelet aggregation appears to be similar to that in animals fed atherogenic diets may be due to the depressed levels of the fatty acid desaturases in platelets. Reduced levels of these enzymes have been observed in other tissues of diabetic animals. Platelet function (adhesion, aggregation, release reaction, Factor-3 actively, LASS production) in streptozotocin treated rats and rabbits will be compared to normal controls. The role of stearic acid in platelet aggregation and in phosphatidyl serine synthesis during aggregation will be studied. The histological location of fatty acid desaturase in retina and retinal capillaries will be determined. The effect of prostaglandin treatment on the skin lesions of diabetic rats will be evaluated.