Total saponins of Cornus officinalis Sieb. ameliorates the endothelium dependent relaxation of mesenteric artery by regulating nitric oxide release in streptozotocin-induced diabetic rats.

OBJECTIVE: To explore the effects of total saponins of Cornus officinalis Sieb. (TSCO) on the contractility and relaxation of mesenteric artery in streptozotocin (STZ)-induced diabetic rats.
METHODS: Sprague Dawley rats were administrated STZ intra-peritoneally at a dosage of 60 mg/kg to induce diabetes. TSCO was administrated at a dosage of 60 mg/kg or 120 mg/kg (per os) to the diabetic rats for 28 days. Glucose and insulin in the serum as well as the responsiveness of mesenteric artery rings were determined.
RESULTS: TSCO decreased the contractile responsiveness to phenylephrine of mesenteric artery rings from diabetic rats, but increased the reactivity to acethylcholine. TSCO (120 mg/kg) ameliorated the baseline release of nitric oxide of mesenteric artery, but had little effect on the induced release of nitric oxide. Rosiglitazone had less effect on the mesenteric artery function than that of TSCO, though it was more effective on lowering blood glucose.
CONCLUSION: The effects of TSCO on mesenteric artery of diabetic rats are dose dependent, and are possibly exerted by lowering blood glucose and ameliorating the release of nitric oxide in the endothelium.