lated fibrosis contributes to cardiac dysfunction. Profibrotic processes are Ca 2ϩ dependent. The effect of aging on the Ca 2ϩ mobilization processes of human ventricular fibroblasts (hVFs) is unclear. Therefore, we tested whether aging altered intracellular Ca 2ϩ release and store-operated Ca 2ϩ entry (SOCE). Disease-free hVFs from 2-to 63-yr-old trauma victims were assessed for cytosolic Ca 2ϩ dynamics with fluo 3/confocal imaging. Angiotensin II or thapsigargin was used to release

more »

... reticulum Ca 2ϩ in Ca 2ϩ -free solution; CaCl2 (2 mM) was then added to assess SOCE, which was normalized to ionomycin-induced maximal Ca 2ϩ . The angiotensin II experiments were repeated after phosphoenolpyruvate pretreatment to determine the role of energy status. The expression of genes encoding SOCErelated ion channel subunits was assessed by quantitative PCR, and protein expression was assessed by immunoblot analysis. Age groups of Ͻ50 and Ն50 yr were compared using unpaired t-test or regression analysis. Ca 2ϩ release by angiotensin II or thapsigargin was not different between the groups, but SOCE was significantly elevated in the Ն50-yr group. Regression analysis showed an age-dependent phosphoenolpyruvate-sensitive increase in SOCE of hVFs. Aging did not alter the mRNA expression of SOCE-related genes. The profibrotic phenotype of hVFs was evident by sprouty1 downregulation with age. Thus, an age-associated increase in angiotensin II-and thapsigargin-induced SOCE occurs in hVFs, independent of receptor mechanisms or alterations of mRNA expression level of SOCErelated ion channel subunits but related to the cellular bioenergetics status. Elucidation of mechanisms underlying enhanced hVF SOCE with aging may refine SOCE targets to limit aging-related progression of Ca 2ϩ -dependent cardiac fibrosis. NEW & NOTEWORTHY Human ventricular fibroblasts exhibit an age-related increase in store-operated Ca 2ϩ influx induced by angiotensin II, an endogenous vasoactive hormone, or thapsigargin, an inhibitor of endoplasmic reticulum Ca 2ϩ -ATPase, independent of receptor mechanisms or genes encoding store-operated Ca 2ϩ entryrelated ion channel subunits. Selective inhibition of this augmented store-operated Ca 2ϩ entry could therapeutically limit aging-related cardiac fibrosis. aging; calcium; cardiac fibroblasts