不同浓度MgCl_2溶液对蟾蜍离体心脏收缩力和心率的影响

Effects of Different MgCl_2 Concentration Solutions on the Contractility and Heart Rate of Isolated Heart of Toad

利用蟾蜍离体心脏灌流法,先用正常任氏液灌流,后用含不同浓度MgCl2的任氏液灌流,观察了不同浓度MgCl2溶液对蟾蜍心肌收缩力和心率的影响。结果表明1.0mmol/L的MgCl2溶液显著增强心肌的收缩力(P<0.05),而对心率无明显影响;2.0mmol/L的MgCl2溶液显著增强心肌的收缩力(P<0.05),却使心率极显著减慢(P<0.01);5.0mmol/L的MgCl2溶液对心肌收缩力和心率的影响均不显著1;0.0mmol/L的MgCl2溶液使心肌收缩力减弱显著(P<0.05),对心率的影响不显著;15.0mmol/L的MgCl2溶液不仅极显著减弱心肌的收缩力(P<0.01),也显著减慢心率(P<0.05)。这些结果表明,细胞外液中低浓度的镁离子增强蟾蜍心肌的收缩力,但高浓度镁离子降低心肌的收缩力。

To study the effects of different MgCl2 concentration solutions on the myocardial contractility and heart rate of toad,isolated heart of toad was perfused with normal Ringer solution followed by the Ringer solution with MgCl2 of a certain concentration.We found that 1.0 mmol/L MgCl2 solution increased the myocardial contraction force(P <0.05),but had no effects on the heart rate;2.0 mmol/L MgCl2 solution increased the myocardial contraction force(P <0.05) and slowed the heart rate significantly(P <0.01);but 5.0 mmol/L MgCl2 solution had no effects on the myocardial contraction force and the heart rate;10.0 mmol/L MgCl2 solution decreased the myocardial contraction force(P <0.05) and had no effects on the heart rate;15.0 mmol/L MgCl2 solution significantly decreased the myocardial contraction force(P <0.01) and slowed the heart rate(P <0.05).These results indicate that extracellular Mg2+ of lower concentration strengthens the myocardial contraction force,but higher concentration reduces the myocardial contraction force.