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

JING-BO CHEN; RONG TAO; HAI-YING SUN; HUNG-FAT TSE; CHU-PAK LAU; GUI-RONG LI

Ca2+ signaling pathways are well studied in cardiac myocytes, but not in cardiac fibroblasts. The aim of the present study is to characterize Ca2+ signaling pathways in cultured human cardiac fibroblasts using confocal scanning microscope and RT-PCR techniques. It was found that spontaneous intracellular Ca2+ (Ca<STACK>i2+</STACK>) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Ca<STACK>i2+</STACK> oscillations was increased to 57.3% by application of 3% fetal bovine serum. Ca<STACK>i2+</STACK> oscillations were dependent on Ca2+ entry. Ca<STACK>i2+</STACK> oscillations were abolished by the store-operated Ca2+ (SOC) entry channel blocker La3+, 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<STACK>i2+</STACK> oscillations. Inhibition of plasma membrane Ca2+ pump (PMCA) and Na+–Ca2+ exchanger (NCX) also suppressed Ca<STACK>i2+</STACK> oscillations. In addition, the frequency of Ca<STACK>i2+</STACK> oscillations was reduced by nifedipine, and increased by Bay K8644 in cells with spontaneous Ca2+ oscillations. RT-PCR revealed that mRNAs for IP3R1-3, SERCA1-3, CaV1.2, 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<STACK>i2+</STACK> oscillations are present in cultured human cardiac fibroblasts and are regulated by multiple Ca2+ pathways, which are not identical to those of the well-studied contractile cardiomyocytes. This study provides a base for future investigations into how Ca2+ 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.

CALCIUM-binding proteins; FIBROBLASTS; CALCIUM in the body; CARRIER proteins; CELLS; CARDIOLOGY

Journal of Cellular Physiology, 2010, Vol 223, Issue 1, p68

0021-9541

Academic Journal

10.1002/jcp.22010