OBJECTIVETo investigate the acute effects of aldosterone (ALD) on mesenteric resistance vessels in normal or heart failure (HF) rats and its mechanism.

METHODSHF model was adopted by in vivo ligation of left anterior descending coronary artery in SD rats; segments of third-order branches of mesenteric artery were isolated and dissected into about 2 mm rings for isometric force recording.

RESULTSPretreated with ALD for 10 min,phenylephrine (PE)-induced contraction of normal mesenteric artery decreased first and then increased compared to control group along with the increase of the concentration of PE while decreased in HF rats. This effect was attenuated by ALD receptor-special antagonist eplerenone partially. ALD increased Ach-induced endothelial-dependent vascular relaxation significantly compared to control group both in normal and HF rats. Pretreated with ALD and dexamethasone (DEX) for 10 min, the effects of ALD on PE-induced contraction were weakened in mesenteric artery both of normal and HF rats. And this reaction of DEX to ALD-treated mesenteric in normal rats was attenuated by RU486 partially.

CONCLUSIONALD has biphasic effect in PE-induced response on mesenteric artery of normal rats, while reduces the sensitivity of mesenteric artery to PE in HF rats. DEX attenuates the biphasic effect of ALD on artery of normal rat partially but has no significant effect on that of HF rats.