Effects of dioscin on rat myocardial contractility / 中国药理学通报

ABSTRACT

Aim To investigate the effects of dioscin ( Dio) on rat myocardial contractility. Methods Left ventricular contractile function was measured using the Langendorff non-recirculating mode of isolated rat heart perfusion. Effects of low, middle and high concentra-tion of Dio were investigated by measuring left ventricu-lar systolic pressure ( LVSP ) and left ventricular end diastolic pressure ( LVEDP) . Also, peak rates of rise/fall of left ventricular pressure ( ± dp/dtmax ) of isolated rat heart were calculated. Effects of Dio on intracellu-lar free calcium concentration in rat H9 c2 cells were measured by using the confocal microscopy. Mitochon-drial membrane potential was detected with multifunc-tional microplate reader. Results With 0. 1, 1 μmol · L-1 Dio, LVSP were significantly enhanced from (11. 55 ± 0. 52), (10. 53 ± 0. 28) kPa to (13. 08 ± 0. 72), (12. 53 ±0. 64) kPa(P<0. 01); +dp/dtmax were dramatically increased from ( 0. 38 ± 0. 10 ) , (0. 40 ± 0. 07) kPa·ms-1 to (0. 42 ± 0. 11), (0. 43 ± 0. 02) kPa·ms-1(P<0. 05). With the 10μmol· L-1 Dio, LVSP and + dp/dtmax were both decreased from (12. 13 ± 0. 33) kPa and (0. 42 ± 0. 04) kPa· ms-1 to ( 9. 46 ± 0. 77 ) kPa and ( 0. 24 ± 0. 04 ) kPa ·ms-1 (P <0. 01). With 0. 1, 1, 10 μmol·L-1 Dio, the relative fluorescence intensity of intracellular free calcium concentrations was increased significantly from (16. 62 ± 0. 89) to (21. 48 ± 0. 80), (25. 68 ± 0. 69) and (19. 84 ± 0. 66)(P <0. 01)respectively. 0. 1, 1μmol·L-1 Dio showed no significant effects on the mitochondrial membrane potential of rat H9 c2 cells, while with effects of 10 μmol·L-1 Dio, the ra-tio of JC-1 monomer and J-aggregates was changed from (1. 14 ± 0. 03) to (1. 35 ± 0. 06)(P<0. 01), indica-ting a decrease in the mitochondrial membrane poten-tial. Conclusion Low and middle concentrations of Dio show a positive inotropic effect on isolated rat heart, as the LVSP and + dp/dtmax are enhanced, which may concern with the increase of the intracellu-lar concentration of Ca2+. It will not cause the calcium overload while the intracellular concentration of Ca2+ is increased by low and middle concentration of Dio in the myocytes except high concentration of Dio.