Long-term effects of untreated diabetes on the arterial wall in rat. An ultrastructural study.

Arterial ultrastructure was examined in twelve untreated streptozotocin-diabetic rats. Five showed severe changes in muscular (coronary, tibial, pulmonary) arteries two months after induction of diabetes. The basement membrane of smooth muscle cells was patchily thickened in these arteries. No similar changes were seen in muscular arteries of the other seven diabetic rats or in 10 control rats. No lesions were found in elastic arteries (aorta, main pulmonary artery) of any diabetic or control animals. Plasma non-esterified fatty acids, total ketone bodies, and glucose levels were higher in the diabetic rats with arterial changes (p less than 0.01) than in the diabetic animals without such changes. The molar ratio of non-esterified fatty acid to albumin in plasma ranged between 2.3-3.3 in the diabetic rats with arterial lesions, 1.4-1.8 in those without such features, and 0.6-1.1 in the controls. The excess of non-esterified fatty acid in plasma during insulin deficiency could be an important factor in the initiation of arterial changes in this model of experimental diabetes.