This study aimed to underline the interaction between hypoxia inducible factor 1(HIF-1) and the inducible NO synthase (iNOS) gene in vivo and their contribution to the delayed myocardial preconditioning induced by acute intermittent hypoxia (IH) in the rat using chromatin immunoprecipitation and pharmacological inhibition by low-dose cadmium. Langendorff-perfused hearts of Wistar rats exposed to normoxia (N) or IH 24 hours earlier were submitted to global ischemia and reperfusion. Effects of iNOS inhibition by aminoguanidine (Ag, 100µM) prior to ischemia or of low-dose injection of cadmium chloride (Cd, 1mg.kg-1) prior to N or IH, were tested. Myocardial HIF-1and iNOS quantification and in vivo chromatin immunoprecipitation of HIF-1bound to the iNOS gene promoter were performed. IH-induced delayed cardioprotection resulted in an improvement in coronary flow and functional recovery at reperfusion and a decrease in infarct size (I/V ratio). Myocardial HIF 1 activity was increased with resulting targeting of the iNOS gene. Ag abolished the cardioprotective effects of IH. Cd treatment prior to IH prevented myocardial HIF-1 activation (72.3±4.0 vs. 42.1±9.7 a.u. after Cd, p0.05), targeting of the iNOS gene, iNOS expression and preconditioning (I/V: 15.9±5.6 vs. 30.1±5.4% after Cd, p0.05). This study is the first to demonstrate the interaction of HIF-1 with the myocardial iNOS gene in situ following hypoxic preconditioning. Prevention of HIF-1 activation and iNOS gene targeting by a single low dose of cadmium abolished the delayed cardioprotective effects and brings insight into the cardiovascular consequences of cadmium exposure.