ADENOVIRUS-MEDIATED GENE-TRANSFER RECONSTITUTES DEPRESSED SARCOPLASMIC-RETICULUM CA2-ATPASE LEVELS AND SHORTENS PROLONGED CARDIAC MYOCYTE CA2+ TRANSIENTS()

Background Decreased expression of the sarcoplasmic reticulum (SR) Ca2 +-ATPase of the cardiac myocyte (SERCA2) and abnormal Ca2+ regulation have been independently linked to human heart failure. This study was designed to determine whether expression of a SERCA2 transgene could r econstitute depressed cardiac myocyte SERCA2 levels, augment SR Ca2+ u ptake, and shorten prolonged excitation-contraction (EC)-associated Ca 2+ transients in neonatal rat cardiac myocytes (NM). Methods and Resul ts Cultured NM were treated with phorbol-12-myristate-13-acetate (PMA) , a compound that decreases endogenous SERCA2 expression and results i n prolongation of EC-associated Ca2+ transients. PMA-treated NM had a 75% reduction in SERCA2 mRNA and a 40% reduction in SERCA2 protein lev els. SERCA2 adenovirus infection increased SERCA2 mRNA expression to 2 .5 times control and reconstituted SERCA2 protein levels in PMA-treate d cells. This reconstitution was associated with a 32.4% reduction in the time for decline of the Indo-1 Ca2+ transient to half-maximum leve ls (t(1/2) [Ca2+](i)) (P<.05). A 34.5% augmentation of oxalate-facilit ated SR Ca2+ uptake was also documented in SERCA2 adenovirus-infected cells (P<.05). Conclusions Adenovirus-mediated expression of a SERCA2 transgene can reconstitute depressed endogenous SERCA2 levels, shorten prolonged Ca2+ transients, and augment SR Ca2+ uptake. It is conceiva ble that such an approach might be used in vivo to normalize altered C a2+ regulation in human heart failure.