| Objective:To observe the effects of metoprolol on Positive inotropic effection induced by levosimendan in vitro case and in vivo experiment of rats.Methods:Heart function parameters such as heart rate(HR),left ventricular developed pressure(LVDP),maximum velocity of left ventricular pressure rise(+dp/dtmax),maximum velocity of left ventricular pressure drop(-dp/dtmax)is measured in this study.Isolated rat hearts were perfused different concentration of levosimedan(30nmol/L,300nmol/L,3000nmol/L)or metoprolol(4?mol/L,20?mol/L,100?mol/L),healthy SD rats were given levosimendan(5,10,20ug/kg/min)through intravenous injection in different velocity or metoprolol(5,10,20mg/kg)through gavage in different doseage,and both were given mixture of levosimendan-metoprolol to observe the positive heart function effects of levosimendan,or levosimendan-metoprolol.Results:1.In the isolated perfused hearts and vivo experiment,a middle dosage of levosimendan definitely increased rat's heart function index without heart rate,a high dosage of levosimendan significantly increased rat's heart function index including heart rate(P<0.05).2.In the isolated perfused hearts,metoprolol have no effect on the heart function,there were no significant differences found between levosimendan group and levosimendan-metoprolol group(P>0.1).3.In vivo experiment,metoprolol significantly decreased rat's heart function and attenuated the rat's positive chronotropic responses to levosimendan(P<0.05),but it did not affect the increase of+dp/dtmax,-dp/dtmax,LVDP(P>0.1).Conclusion:In the isolated perfused hearts and vivo experiment,levosimendan definitely improve rat's heart function,but a high dosage of levosimendan significantly increase rat's heart rate.metoprolol can counteract levosimendan-induced tachycardia in vivo condition,but did't effect the positive inotropic effection caused by levosimendan. |
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