D On The Cardiovascular Effects Of Cyclovirobuxine Mechanism

Part 1. Effect of cyclovirobuxine D(CVB-D) on intracellular free Ca2* concentration in neonatal rat cardiomyocytesNeonatal rat cardiomyocytes was cultured to measure intracellular free Ca2+ concentration by calcium fluorescent probe Fluo-3/AM and laser confocal microscope. Result: In Hanks solution, 10-7,10-6 10-5mol-L-1 CVB-D can elevate [Ca2*], its peak values reached 1.93?. 56, 5. 90 ?.92 , 14. 36 ?. 27 respectively; which indicate that the level of [Ca2+]acts in an dose-dependent. Conclusion : CVB-D was found to increase intracellular free Ca2* concentration. The increasing of [Ca2+], may was caused by releasing from intracellular stores and extracellular Ca2+ influx.Part 2. Effect of cyclovirobuxine D(CVB-D) on intracellular free Ca2* concentration in acute isolated rat cardiomyocytes Intracellular calcium concentration in acute isolated cardiomyocytes was measured with the Ca2+ indicator Fluo-3/AM and laser scanning confocal microscopy.Result: ( 1 ) In Tyrode solution, 1(T, 10-6, KTmol-L-1 CVB-D can elevate [Ca2*L its peak values reached 1.53?.32,7.54?.01,11.74?.25 respectively; which indicate that the level of [Ca2+] acts in an dose-dependent. (2)[Ca2*L was also signficantly higher in Tyrode solution than that in D-Tyrodes solution (P<0. 01). (3) In D-Tyrode solution with ryanodine, CVB-D had no effect on level of [Ca2+]; compared with group of D-Tyrode without ryanodine (P>0.05) . Conclusion : CVB-D was found to increase intracellular free Ca2+ concentration. The increasing of [Ca2*] s wascaused by releasing from intracellular stores and extracellular Ca2* influx. The increasing of [Ca2+] caused by releasing from intracellular stores may not act in ryanodine receptor. Part 3. Effect of CVB-D on L-type calcium current and transient outwardpotassium current in rat ventricular myocyte The patch-clamp whole cell recording technique was used to observe effect of CVB-D on L-type calcium current and transient outward potassium current in rat ventricular myocyte. Result: CVB-D l(Tmol-L~\ 10-6mol-L-1can increase respectively the peak current L-type calcium current from (-1162.241110.19) pA to (-1335. 52181. 58)pA and (-1787. 07?18. 41) pA. Conclusion : CVB-D can increase L-type calcium current and proplong action potential .But it wasn't remarkable effect on transient outward potassium current in rat ventricular myocyte. So it can be used for the treatment of heart failure and arrhythmias.