目的：观察薯蓣皂苷( dioscin,Dio)对大鼠心肌收缩力的影响。方法采用 Langendorff 逆行主动脉灌流法对大鼠离体心脏进行灌流,利用压力感受器插管法测定左心室相关心功能参数,记录低、中和高3个浓度Dio对左心室收缩压(LVSP)、左心室舒张末期压(LVEDP)、左心室内压最大上升/下降速率(± dp/dtmax )的影响。利用激光共聚焦显微镜观察Dio对H9c2细胞内Ca2+浓度的影响,并利用多功能酶标仪观察药物对细胞线粒体膜电位的影响。结果0．1、1μmol·L-1 Dio可明显增加LVSP,由(11．55±0．52)、(10．53±0．28) kPa 分别增加至(13．08±0．72)、(12．53±0．64) kPa( P<0．01)；增加+dp/dtmax由(0．38±0．10)、(0．40±0．07) kPa·ms-1分别增加至(0．42±0．11)、(0．43±0．02) kPa· ms-1( P <0．05)。10μmol · L-1 Dio 则使 LVSP 由(12．13±0．33) kPa减至(9．46±0．77) kPa(P<0．01),使+dp/dtmax由(0．42±0．04) kPa · ms-1降为(0．24±0．04) kPa·ms-1( P <0．01)。0．1、1、10μmol · L-1的 Dio 可使H9c2细胞中Ca2+相对荧光强度由(16．62±0．89)分别增加至(21．48±0．80)、(25．68±0．69)和(19．84±0．66)(P <0．01)。0．1、1μmol·L-1 Dio对H9c2细胞线粒体膜电位无明显影响,而10μmol · L-1 Dio会使JC-1单体与聚合物的比值由(1．14±0．03)增加为(1．35±0．06)(P<0．01),即引起线粒体膜电位下降。结论低、中浓度Dio可增加LVSP和+dp/dtmax ,表现正性肌力作用,机制为增加细胞内Ca2+浓度。并且,其在增加细胞内Ca2+浓度的同时并不会引起钙超载,仅高浓度出现。%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.
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