Ischemia/reperfusion causes endothelial dysfunction. Prolongation of acidosis during initial cardiac reperfusion limits infarct size in animal models, but the effects of acidic reperfusion on vascular function are unknown. The present work analyzes the effects of acidic reoxygenation on vascular responses to different agonists in rat aortic rings. Arterial rings obtained from Sprague-Dawley rat aorta were placed in organ baths containing a Krebs solution oxygenated at 37°C (pH 7.4). After equilibration (30 mN, 1h), the effects of acidosis (pH 6.4) on aortic responses to acetylcholine and noradrenaline were initially assessed under normoxic conditions. Thereafter, the effects of acidosis during hypoxia (1h) or reoxygenation on aortic responses to acetylcholine, noradrenaline or sodium nitroprusside were analyzed and compared with those observed in control rings. Acidosis did not modify aortic responses to acetylcholine nor adrenaline during normoxia. In contrast, rings submitted to hypoxia and reoxygenated at pH 7.4 showed a reduction in vasodilator responses to acetylcholine and in contractions to noradrenaline, with no change in responses to sodium nitroprusside. Reoxygenation at pH 6.4 did not modify the depressed response to noradrenaline, but enhanced the recovery of acetylcholine-induced vasorelaxation. Cumulative concentration-response curves to acetylcholine showed an increased responsiveness to this drugs in rings reoxygenated at low pH. This functional improvement was associated with preservation of aortic cGMP content after stimulation of reoxygenated rings with acetylcholine. In conclusion, acidic reoxygenation preserves endothelial function in arterial rings submitted to simulated ischemia, likely through preservation of cGMP signalling.