Adenovirus-Mediated Gene Transfer Reconstitutes Depressed Sarcoplasmic Reticulum Ca 2+ -ATPase Levels and Shortens Prolonged Cardiac Myocyte Ca 2+ Transients

Abstract

Background Decreased expression of the sarcoplasmic reticulum (SR) Ca 2+ -ATPase of the cardiac myocyte (SERCA2) and abnormal Ca 2+ regulation have been independently linked to human heart failure. This study was designed to determine whether expression of a SERCA2 transgene could reconstitute depressed cardiac myocyte SERCA2 levels, augment SR Ca 2+ uptake, and shorten prolonged excitation-contraction (EC)–associated Ca 2+ transients in neonatal rat cardiac myocytes (NM). Methods and Results Cultured NM were treated with phorbol-12-myristate-13-acetate (PMA), a compound that decreases endogenous SERCA2 expression and results in prolongation of EC-associated Ca 2+ transients. PMA-treated NM had a 75% reduction in SERCA2 mRNA and a 40% reduction in SERCA2 protein levels. SERCA2 adenovirus infection increased SERCA2 mRNA expression to 2.5 times control and reconstituted SERCA2 protein levels in PMA-treated cells. This reconstitution was associated with a 32.4% reduction in the time for decline of the Indo-1 Ca 2+ transient to half-maximum levels ( t 1/2 [Ca 2+ ] i ) ( P <.05). A 34.5% augmentation of oxalate-facilitated SR Ca 2+ 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 Ca 2+ transients, and augment SR Ca 2+ uptake. It is conceivable that such an approach might be used in vivo to normalize altered Ca 2+ regulation in human heart failure.