Modulation effect of Smilax glabra flavonoids on ryanodine receptor mediated intracellular Ca2+ release in cardiomyoblast cells

Smilax glabra rhizome, a plant material from Liliaceae family, is a widely used traditional Chinese medicine for anti-cardiac hypertrophy treatment. We have previously found that Smilax glabra flavonoids (SGF) exerted such anti-cardiac hypertrophy activity. However, the mechanism of this activity of SGF has not been clarified yet. This study was aimed to investigate the inhibitory role of SGF on intracellular Ca2+ release in rat cardiomyoblast cells (H9C2). Intracellular Ca2+ release was determined by Ca2+ indicator fluorescence (fluo 4-AM) in H9C2 cell line. SGF at concentrations of 0.25, 0.5, 1.0mg/ml significantly inhibited the phenylephrine or angiotensin II induced intracellular Ca2+ release in a dose-dependent manner. Furthermore, SGF could also inhibit ryanodine receptor (RyR) agonist caffeine induced Ca2+ release and phenylephrine (PE)-induced Ca2+ release under the condition in which inositol trisphosphate (IP3) receptors were blocked with 2-Aminoethoxydiphenyl borate (2-APB). Nevertheless, SGF had no impact on PE-induced Ca2+ release under the condition in which RyRs were blocked with tetracaine. Our results suggest that the protective effects of SGF are mediated via targeting inhibition of RyR mediated intracellular Ca2+ release.