Separate Regulation of Heme Oxygenase and Heat Shock Protein 70 mRNA Expression in the Rat Heart by Hemodynamic Stress

To elucidate the role of heat shock proteins in hearts, we examined the expression of heme oxygenase (HO) and heat shock protein 70 (HSP70) mRNAs in hearts of rats subjected to hypoxia or pulmonary artery banding, both of which produce pressure overload to the right ventricle. At 3 d of hypoxia, HO mRNA levels were elevated about fourfold compared to the basal levels in both right and left ventricles, while HSP70 mRNA s was not induced at all. Pulmonary artery banding markedly and immediately (within 6 h) increased HO mRNA levels in both ventricles, but induced HSP70 mRNA only in the right ventricle. This is the first in vivo evidence showing the separate regulation of HO and HSP70 gene expression in hearts by hemodynamic stress.