RESUMEN
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.
RESUMEN
Mammalian oocyte maturation and early embryo development processes are Ca(2+)-dependent. In this study, we used confocal microscopy to investigate the distribution pattern of Ca2+ and its dynamic changes in the processes of bovine oocytes maturation, in vitro fertilization (IVF), parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT) embryo development. During the germinal vesicle (GV) and GV breakdown stage, Ca2+ was distributed in the cortical ooplasm and throughout the oocytes from the MI to MII stage. In IVF embryos, Ca2+ was distributed in the cortical ooplasm before the formation of the pronucleus. In 4-8 cell embryos and morulas, Ca2+ was present throughout the blastomere. In PA embryos, Ca2+ was distributed throughout the blastomere at 48 h, similar to in the 4-cell and 8-cell phase and the morula. At 6 h after activation, there was almost no distribution of Ca2+ in the SCNT embryos. However, Ca2+ was distributed in the donor nucleus at 10 h and it was distributed throughout the blastomere in the 2-8 cell embryos. In this study, Ca2+ showed significant fluctuations with regularity of IVF and SCNT groups, but PA did not. Systematic investigation of the Ca2+ location and distribution changes during oocyte maturation and early embryo development processes should facilitate a better understanding of the mechanisms involved in oocyte maturation, reconstructed embryo activation and development, ultimately improving the reconstructed embryo development rate.