Inhibition of NF kappa B activation by pyrrolidine dithiocarbamate prevents in vivo hypoxia/reoxygenation-mediated myocardial angiogenesis

This study sought to examine the effect of nonlethal moderate whole body hy poxic challenge (10% O2/90% N-2) on rat myocardial angiogenesis. Sprague Da wley rats were subjected to 4 h of systemic normobaric hypoxemic hypoxia (1 0 +/- 0.4% O-2) in an anesthesia chamber or to 4 h of normoxia (ambient 20. 9 +/- 0.4% O-2) to time-match the duration of hypoxia. All rats were then k ept under normoxic conditions. Rats were sacrificed and hearts harvested ei ther after 2 h for subsequent electrophoretic mobility gel shift assay for NF kappaB, or after 24 h for subsequent Western blot analysis for vascular endothelial growth factor (VEGF) and after 7 days for immunohistochemistry for capillary density measurement. We also used pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF kappaB, before 1 h of hypoxia to establish the possible role of NF kappaB in modulating myocardial angiogenesis. The resul ts showed significant induction of VEGF protein expression after 4 h of hyp oxia followed by 24 h of reoxygenation in the rat myocardium. The DNA bindi ng activity of NF kappaB was increased compared with the hypoxic group. How ever inhibition of NF kappaB by PDTC decreased capillary density significan tly when compared with the hypoxic group. These findings demonstrate the ro le of NF kappaB and VEGF in myocardial angiogenesis for the first time.