COEXISTENCE OF DIABETES AND HYPERTENSION RESULTS IN UNIQUE STRUCTURAL ALTERATIONS IN THE RENAL-ARTERY IN RATS BEYOND THAT FOUND WITH DIABETES ALONE

Numerous investigators have presented evidence of increased mortality in patients with diabetes mellitus due to cardiovascular disease. It is still unclear as to the reasons why there is a predisposition to vascular pathology that in the advanced state leads to atherosclerosis. Our hypotheses were: (1) The condition of diabetes mellitus in a streptozocin animal model may show vascular changes similar to early pathology in macrovessels and (2) since the model is normotensive, inducing hypertension will result in early atherogenic pathology. We carried out a quantitative analysis of the renal artery using light and electron microscopy to test the hypotheses. Male Wistar rats had diabetes mellitus induced using streptozocin and 1 week later half of the diabetic animals had hypertension induced with deoxycorticosterone acetate (DOCA). Samples were taken following 7 weeks of diabetes, or 7 weeks of diabetes with DOCA administration during the final 6 weeks. The renal artery from the diabetic group did not have any differences in wall or luminal dimensions from control, but did have proportionately more extracellular matrix than smooth muscle in the tunica media. This is evidence of structural change, in a large supply artery, as a manifestation of diabetes mellitus, similar to that seen in vascular disease. Vessels from the control/hypertensive had a significantly thickened tunica media as did the diabetic/hypertensive over control values. The latter also had proportionately even greater significant elevation of the extracellular matrix compared with either the diabetic or control/hypertensive. In addition, only the diabetic/hypertensive group showed marked subendothelial invasion of macrophage type cells and deposits of various shapes and densities. We have, therefore, demonstrated significant vascular alteration due to the diabetic condition in this animal models and also shown that with hypertension and diabetes combined, the early vascular pathology is exacerbated.