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

J Cell Physiol. 2010 Apr;223(1):68-75. doi: 10.1002/jcp.22010.


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(i) (2+)) oscillations were present in about 29% of human cardiac fibroblasts, and the number of cells with Ca(i) (2+) oscillations was increased to 57.3% by application of 3% fetal bovine serum. Ca(i) (2+) oscillations were dependent on Ca(2+) entry. Ca(i) (2+) 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(i) (2+) oscillations. Inhibition of plasma membrane Ca(2+) pump (PMCA) and Na(+)-Ca(2+) exchanger (NCX) also suppressed Ca(i) (2+) oscillations. In addition, the frequency of Ca(i) (2+) 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(i) (2+) 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sodium-Calcium Exchanger / antagonists & inhibitors
  • Sodium-Calcium Exchanger / metabolism
  • Time Factors
  • Type C Phospholipases / antagonists & inhibitors
  • Type C Phospholipases / metabolism


  • Calcium Channel Agonists
  • Calcium Channel Blockers
  • Enzyme Inhibitors
  • Inositol 1,4,5-Trisphosphate Receptors
  • RNA, Messenger
  • Sodium-Calcium Exchanger
  • Type C Phospholipases
  • Plasma Membrane Calcium-Transporting ATPases
  • Calcium