EFFECTS OF DIABETES AND UREMIA ON MESENTERIC VASCULAR REACTIVITY

Background. Diabetes and uremia are comorbid conditions that have sign ificant effects on cardiovascular physiology. These studies were desig ned to examine the effects of diabetes and uremia on vascular reactivi ty. Methods. Sprague-Dawley rats were divided into control (C), diabet ic (D), uremic (U), and diabetic/uremic (D + Ui groups. Diabetes (D, D + U groups) was induced with an injection of streptozotocin. Uremic ( U, D + U groups) was produced by seven-eighths nephrectomy. Serum gluc ose, blood urea nitrogen creatinine, creatinine clearance, and protein excretion were measured at baseline and before microvascular studies at 4 or 8 weeks after injection. Vascular reactivity was studied in is olated, pressurized and superfused segments of mesenteric arterioles ( 300 mu m) Changes in internal vessel diameter were measured in respons e to phenylephrine (10(-8) to 10(-4) mol/L), acetylcholine (10(-9) to 10(-5) mol/L), and nitroprusside (10(-9) to 10(-2) mol/L). Results. Re sults at 4 and 8 weeks were similar in all groups. Vasoconstrictor res ponses to phenylephrine and endothelium-independent vasodilator respon ses to nitroprusside were not altered in any depressed in both diabeti c groups (D and D + U, p < 0.01 versus control), and there were no dif ferences between the two diabetic groups. Conclusions. Streptozotocin- induced diabetes results in impairment of endothelial-dependent (nitri c oxide mediated) vasodilator responses in mesenteric resistance vesse ls, which are unaffected by coexisting uremia. Uremia has little effec t on mesenteric vascular reactivity in this model.