Cardioprotective role of S-Nitroso Human Serum Albuminduring regional myocardial ischemia-reperfusion.

BACKGROUND: The early period of reperfusion after myocardial ischemia is critical for endothelial dysfunction and the impairment of nitric oxide synthesis plays a critical role. We investigated the cardioprotective effect of S-NO-HSA in a regional myocardial ischemia/reperfusion rat model reproducing clinical scenarios. METHODS AND RESULTS: Male Wistar rats (n: 120) underwent reversible occlusion of the left anterior descending artery for 30 minutes and subsequent reperfusion for 24 hours. The animals were randomly treated with S-NO-HSA (0.3 μmol/kg/h) or human serum albumin (HSA) infusion. The infusion started 15 minutes before the beginning of ischemia in a group (Pre-I) whereas it starter 15 min after the initiation of ischemia in the other group (Post-I). The infusion continued until the first 30 minutes of reperfusion in both groups. Ventricular systolic and diastolic function was evaluated during early and late reperfusion (120 min and 24 h) in vivo at different preloads by a Millar microtip P-V conductance catheter. Hearts were excised after reperfusion to determine infarct size (IS) and area at risk (AR). Biopsies were obtained to measure high-energy phosphates, the expression of endothelial nitric oxide synthase (eNOS) and inducile nitric oxide synthase (iNOS) and the production of NFkB. Treatment with S-NO-HSA had a significative effect in reducing IS (42.2% +/-3.5 vs. 65.3 +/-4.2; p<0.05), the maximum effect is produced when the drug is administered before ischemia. S-NO-HSA effect on LV systolic function is evident considering the preload independent contractility parameters: maximal slope of the systolic pressure increment end diastolic volume relationship (dP/dtMAX-EDV), the slope EMAX of the end-systolic P-V relationship and the preload recruitable stroke work (PRSW) were significantly increased during reperfusion in all treated animals and after ischemia only in the pre-treated group (Pre-I). The LV diastolic function was improved by S-NO-HSA treatment. Tau-Weiss (index of ventricular relaxation), LV end-diastolic pressure (LVEDP) and end-diastolic P-V relationship (EDPVR) (indexes of ventricular stiffness) were significantly decreased with S-NO-HSA both in Pre-I and Post-I group after ischemia and during the 24 h reperfusion. NO supplementation by S-NO-HSA led to partial and in Pre-I group to total preservation of high energy phosphates. Phosphocreatine (CrP) content was preserved in Pre-I group (5.25 +/- 1.65 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) and in Post-I group (3.85 +/- 1.12 vs. 1.53 +/- 1.29 μmol/g protein; p < 0.05) after 24 h reperfusion. Indeed energy charge was significantly higher only in the Pre-I group (0.62 +/- 0.07 vs 0.30 +/- 0.07). S-NO-HSA did not change the constitutive eNOS expression (measured by immunohistochemistry), instead it prevent the NFkB activation (quantified by EMSA) and therefore the iNOS mRNA expression (measured by Northern Blot). CONCLUSIONS: S-NO-HSA limits the infarct size, improves diastolic and systolic function and the energetic reserve of the heart after regional myocardial ischemia/reperfusion. These results suggest that S- NO-HSA might be an interesting option for patients undergoing regional myocardial ischemia reperfusion.