Chrysosplenol C가 분리한 백서 심실 근세포 Ca2+ Transient에 미치는 효과

Effects of Chrysosplenol C on Intracellular Ca2+ Transient in Isolated Rat Ventricular Myocytes

Chrysosplenol C [5,6-dihydroxy-2-(4-hydroxy-3-methoxyphenyl)-3,7-dimethoxychromen-4-one] is a flavonoid found in Miliusa balansae and Pterocaulon sphacelatum. We have recently shown that chrysosplenol C has positive inotropic effect in isolated rat ventricular myocytes. In the present study, we explored a possible mechanism for the positive inotropic effect of chrysosplenol C by examining intracellular Ca2+ transients during action potentials. The intracellular Ca2+ transients were measured by confocal Ca2+ imaging in field-stimulated single rat ventricular myocytes. Chrysosplenol C (50 μM) significantly increased the magnitudes (ΔF/F0) of Ca2+ transients (control, 1.08±0.05; chrysosplenol C, 1.25±0.03;n=8, P<0.01). Half decay time of the action potential-induced Ca2+ transient was not altered by chrysosplenol C (50 μM) (control, 154±6 ms; chrysosplenol C, 167±11 ms; n=21). The Ca2+ content in the sarcoplasmic reticulum (SR), measured as caffeine (10 mM)-induced Ca2+ transient, was significantly decreased by chrysosplenol C (50 μM). These results indicate that chrysosplenol C increases Ca2+ transients without altering Ca2+ removal kinetics in ventricular myocytes, providing a possible mechanism for its positive inotropic effect.