THE EFFECT OF VANADYL TREATMENT ON VASCULAR RESPONSIVENESS OF STREPTOZOTOCIN-DIABETIC RATS

Vanadyl sulphate has been demonstrated to possess insulin-like effects in streptozotocin (STZ) diabetic rats, including the normalization of hyperglycaemia and the prevention of diabetes-induced cardiac dysfunc tion. However, the effectiveness of vanadyl sulphate on diabetes-relat ed vascular aberrations has not been questioned. Hence, in the present work, we have specifically addressed the question of whether chronic oral vanadyl sulphate treatment has any beneficial effect on diabetes- induced changes in vascular reactivity. Male albino rats were injected with a single intravenous dose of STZ (55 mg/kg). Vanadyl sulphate wa s administered in the drinking water at a concentration of 1 mg/ml fro m 7 days after the STZ injection and treatment was maintained for 10 w eeks. Vanadyl intake was accompanied by decreased blood glucose and se rum insulin levels. The effects of diabetes on vascular smooth muscle function were assessed by the responsiveness of aortae to noradrenalin e and KC1. Contractile responses of the diabetic aortae were found to be significantly increased as compared with controls. However, there w ere no significant differences in pD(2) values of the agonists in eith er of the groups. Treatment of diabetic rats with vanadyl sulphate com pletely prevented the increases in responsiveness of aortae to noradre naline and KC1. The effect of diabetes on the fast and slow components of noradrenaline-induced contraction was also examined. Both componen ts of the response to noradrenaline were significantly increased in di abetic aortae. These changes were also prevented by vanadyl sulphate t reatment. The data demonstrate that 10-week vanadyl sulphate treatment results in improved vascular reactivity of diabetic rats.