Interleukin-2 Improves Vascular Functions in Streptozotocin-induced Diabetic Rats

To investigate changes in vascular functions in streptozotocin (STZ)-induced diabetic rats and the effect of interleukin-2 (IL-2), male Sprague-Dawley rats were randomly divided into a normal group, a diabetic control group, and diabetic groups treated with a low dose (5000 U/kg/d) or a high dose of IL-2 (50000 U/kg/d) for five weeks. Rats were injected with STZ (60 mg/kg, i.p.) to induce diabetes. The contractions in response to KCl, phenylephrine (PE), and CaCl₂, and the vasorelaxant effect of acetylcholine (ACh) on rings from thoracic aortae preconstricted with PE were determined using organ bath technique. In the diabetic group, the contractile responses to PE were significantly impaired. Treatment with IL-2 improved this response, but the high dose was less effective. However, IL-2 attenuated the contractile response to KCl in the diabetic groups in a dose-dependent manner. The high concentration of IL-2 decreased the contractile response to CaCl₂. ACh caused a dose-dependent relaxation of aortic rings that was impaired in the diabetic group. The vascular responses in IL-2 treated groups were preserved. The results indicate that IL-2 can improve vascular function in diabetic rat.