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

• Published in: Journal of cellular physiology 2010-04, Vol.223 (1), p.68-75
• Main Authors: Chen, Jing-Bo, Tao, Rong, Sun, Hai-Ying, Tse, Hung-Fat, Lau, Chu-Pak, Li, Gui-Rong
• Format: Article
• Language: English
• Subjects: Adult; Calcium - metabolism; Calcium Channel Agonists - pharmacology; Calcium Channel Blockers - pharmacology; Calcium Signaling - drug effects; Calcium Signaling - genetics; Cells, Cultured; Enzyme Inhibitors - pharmacology; Fibroblasts - drug effects; Fibroblasts - metabolism; Heart Ventricles - cytology; Heart Ventricles - drug effects; Heart Ventricles - metabolism; Humans; Inositol 1,4,5-Trisphosphate Receptors - drug effects; Inositol 1,4,5-Trisphosphate Receptors - metabolism; Microscopy, Confocal; Plasma Membrane Calcium-Transporting ATPases - antagonists & inhibitors; Plasma Membrane Calcium-Transporting ATPases - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Sodium-Calcium Exchanger - antagonists & inhibitors; Sodium-Calcium Exchanger - metabolism; Time Factors; Type C Phospholipases - antagonists & inhibitors; Type C Phospholipases - metabolism
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.22010

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 i2+) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Ca i2+ oscillations was increased to 57.3% by application of 3% fetal bovine serum. Ca i2+ oscillations were dependent on Ca2+ entry. Ca i2+ 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 i2+ oscillations. Inhibition of plasma membrane Ca2+ pump (PMCA) and Na+–Ca2+ exchanger (NCX) also suppressed Ca i2+ oscillations. In addition, the frequency of Ca i2+ 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 i2+ 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.