Hypoxia stimulates myocardial RNA synthesis and histone acetylation.

Fifteen minutes of hypoxic perfusion (95%N2:5%CO2) produced a 75%-80% decrease in contraction rate with a slight increase in coronary flow. During aerobic recovery (95%O2:5%CO2), hemodynamic function returned to control values within 3-5 min of perfusion. Uridine incorporation into total tissue RNA was stimulated 78% after 60 min of recovery perfusion. The acetylation of total nucleohistones was significantly (P .05) increased after 40 and 60 min of aerobic perfusion. These data suggest that 1) a brief period of hypoxia was sufficient to stimulate RNA synthesis and 2) enhanced histone acetylation was associated with increased myocardial RNA synthesis.