[Preischemic infusion of alpha-human atrial natriuretic peptide elicits myoprotection through a nitric oxide-dependent mechanism]

Abstract

Objectives: Alpha-human atrial natriuretic peptide (alpha-hANP) has been used to treat patients with heart failure due to its natriuretic and vasodilatory activities. Recent reports have suggested that alpha-hANP generates nitric oxide (NO) that is known to be involved in myoprotective mechanisms. In this study, the effects of preischemic infusion of alpha-hANP against reperfusion injury were evaluated.

Methods: Isolated rat (Sprague-Dawley rat, age 8-10 weeks, weight 260-340 g) hearts were subjected to Langendorff perfusion with buffered Krebs-Henseleit solution and were divided into three groups: Six hearts were treated with 0.1 microM of alpha-hANP for 10 min (Group H), six hearts with 1 mM of a NO synthetase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) for 5 min before alpha-hANP (Group L), and six hearts served as the controls with no interventions (Group C). All groups were then subjected to 20 min of global ischemia followed by 120 min of reperfusion. Left ventricular pressures and coronary flow were measured throughout the experiment and infarct size was evaluated at the end of the experiments.

Results: Treatment with alpha-hANP significantly reduced infarct size as compared to control hearts whereas pretreatment with L-NAME almost reversed the preventive effect (Group C = 42.7 +/- 2.3%, Group H = 26.1 +/- 2.8% *, Group L = 39.0 +/- 1.6%; * p < 0.01 vs Group C). There were no significant differences in left ventricular pressure and coronary flow between the three groups.

Conclusions: Preischemic infusion of alpha-hANP may provide myoprotective effects against postischemic reperfusion, possibly through a NO-dependent mechanism.