EFFECTS OF LEVOSIMENDAN, A CARDIOTONIC AGENT TARGETED TO TROPONIN-C, ON CARDIAC-FUNCTION AND ON PHOSPHORYLATION AND CA2+ SENSITIVITY OF CARDIAC MYOFIBRILS AND SARCOPLASMIC-RETICULUM IN GUINEA-PIG HEART

被引:215
作者
EDES, I
KISS, E
KITADA, Y
POWERS, FM
PAPP, JG
KRANIAS, EG
SOLARO, RJ
机构
[1] UNIV ILLINOIS, COLL MED, DEPT PHYSIOL & BIOPHYS MC901, CHICAGO, IL 60612 USA
[2] ALBERT SZENT GYORGYI MED UNIV, DEPT MED 2, H-6701 SZEGED, HUNGARY
[3] ALBERT SZENT GYORGYI MED UNIV, DEPT PHYSIOL, H-6701 SZEGED, HUNGARY
[4] ALBERT SZENT GYORGYI MED UNIV, DEPT PHARMACOL, H-6701 SZEGED, HUNGARY
[5] UNIV CINCINNATI, DEPT PHARMACOL & CELL BIOPHYS, CINCINNATI, OH 45267 USA
关键词
LEVOSIMENDAN; TROPONIN C; CARDIAC CONTRACTILITY;
D O I
10.1161/01.RES.77.1.107
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
A new cardiotonic agent, (R)-[[4-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)-phenyl] hydrazono]propanedinitrile (Levosimendan), has been developed and screened for its ability to bind to cardiac troponin C. In perfused hearts, low concentrations of 0.03 or 0.1 mu mol/L Levosimendan increased +dP/dt, but did not affect the speed of relaxation and produced only a slight increase in spontaneous heart rate in the hearts perfused with 0.1 mu mol/L of the drug. In these same hearts, perfusion with 0.03 mu mol/L Levosimendan did not alter the P-32 incorporation into troponin I or C protein, whereas a slight but significant increase was noted for phospholamban, with no detectable change in tissue cAMP levels. Administration of 0.1 or 0.3 mu mol/L Levosimendan significantly increased myocardial cAMP levels as well as the phosphorylation of phospholamban, troponin I, and C protein. Levosimendan (0.03 to 10 mu mol/L) reversibly increased force generated by detergent-extracted fiber bundles over a range of submaximally activating free Ca2+ concentrations with no significant effect on maximum force or on Ca2+ binding to myofilament troponin C. There was no direct effect of Levosimendan on Ca2+ uptake by vesicles of sarcoplasmic reticulum (SR). In contrast, under conditions optimal for cAMP-dependent phosphorylation, Levosimendan slightly but significantly lowered the concentration of Ca2+, yielding half-maximal uptake rates by the SR vesicles. Our results indicate that at low concentrations Levosimendan acts preferably as a Ca2+ sensitizer, whereas at higher concentrations its action as a phosphodiesterase inhibitor contributes to the positive inotropic effect.
引用
收藏
页码:107 / 113
页数:7
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