Multiple Ca2+ signaling pathways regulate intracellular Ca2+ activity in human cardiac fibroblasts

✍ Scribed by Jing-Bo Chen; Rong Tao; Hai-Ying Sun; Hung-Fat Tse; Chu-Pak Lau; Gui-Rong Li

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 997 KB
• Volume: 223
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.22010

✦ Synopsis

Abstract

Ca^2+^ signaling pathways are well studied in cardiac myocytes, but not in cardiac fibroblasts. The aim of the present study is to characterize Ca^2+^ signaling pathways in cultured human cardiac fibroblasts using confocal scanning microscope and RT‐PCR techniques. It was found that spontaneous intracellular Ca^2+^ (Ca) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Ca oscillations was increased to 57.3% by application of 3% fetal bovine serum. Ca oscillations were dependent on Ca^2+^ entry. Ca oscillations were abolished by the store‐operated Ca^2+^ (SOC) entry channel blocker La^3+^, the phospholipase C inhibitor U‐73122, and the inositol trisphosphate receptors (IP3Rs) inhibitor 2‐aminoethoxydiphenyl borate, but not by ryanodine. The IP3R agonist thimerosal enhanced Ca oscillations. Inhibition of plasma membrane Ca^2+^ pump (PMCA) and Na^+^–Ca^2+^ exchanger (NCX) also suppressed Ca oscillations. In addition, the frequency of Ca oscillations was reduced by nifedipine, and increased by Bay K8644 in cells with spontaneous Ca^2+^ oscillations. RT‐PCR revealed that mRNAs for IP3R1‐3, SERCA1‐3, Ca~V~1.2, NCX3, PMCA1,3,4, TRPC1,3,4,6, STIM1, and Orai1‐3, were readily detectable, but not RyRs. Our results demonstrate for the first time that spontaneous Ca oscillations are present in cultured human cardiac fibroblasts and are regulated by multiple Ca^2+^ pathways, which are not identical to those of the well‐studied contractile cardiomyocytes. This study provides a base for future investigations into how Ca^2+^ signals regulate biological activity in human cardiac fibroblasts and cardiac remodeling under pathological conditions. J. Cell. Physiol. 223: 68–75, 2010. © 2009 Wiley‐Liss, Inc.