Basic fibroblast growth factor activates calcium channels in neonatal rat cardiomyocytes

Area of Science:

• Cardiology
• Molecular Biology
• Cell Signaling

Background:

• Basic fibroblast growth factor (bFGF) is a known mitogen for cardiomyocytes.
• bFGF influences gene expression in adult ventricular myocytes, potentially contributing to myocardial hypertrophy under stress.
• The initial molecular events following bFGF cell activation remain largely uncharacterized.

Purpose of the Study:

• To investigate the early molecular mechanisms of bFGF action in cultured neonatal rat cardiomyocytes.
• To identify bFGF receptors and characterize downstream signaling pathways, particularly calcium channel involvement.

Main Methods:

• Biochemical and electrophysiological techniques were employed.
• Cardiomyocytes were cultured from neonatal rat ventricles.
• Receptor binding affinities, beating frequencies, and calcium channel activity were measured.

Main Results:

• Two classes of bFGF receptors (high and low affinity) were identified on differentiated cardiomyocytes.
• bFGF stimulation increased cardiomyocyte beating frequency by approximately 40%.
• bFGF activated non-specific, voltage-independent calcium channels (12pS), with inositol 1,4,5-trisphosphate potentially acting as a second messenger.

Conclusions:

• Cultured cardiomyocytes possess novel calcium channels activated by bFGF.
• bFGF-induced calcium channel activation is a key early step in the cellular response to this growth factor.
• These findings provide insight into the molecular basis of bFGF-mediated cardiomyocyte growth and adaptation.