Effects Of Single Low Dose Intravenous Injection Of Milrinone On Myocardial Stunning In Experimental Rabbits

Objective The research for milrinone on myocardial stunning mainly was focused on continuous intravenous injection or on high dosage. Effects of single low-dose intravenous injection of milrinone on myocardial stunning rabbits have not been reported in the recent magazine. This experiment used model of myocardial stunning in domestic rabbits and injected low dosage( 5 ug/kg ) milrinone in vein after ligaturing left anterior descending artery(LAD). The myocardial function was reflected in the hemodynamics indices such as HR, LVDP, LVSP, +DP/DTmax, -DP/Dtmax. Cardiac troponin I( cTnI ),CK,CK-MB, AST, LDH and HBDH were also measured to indicate the injury of myocardium. The effects of single low-dose intravenous milrinone on myocardial stunning in rabbits were observed. Clinical application of milrinone on stunned myocardium was also observed. Furthermore, the new method and the new convenient clinical application of milrinone could be found. Methods 30 domestic rabbits were instrumented surgicaly and divided randomly into 3 groups, 10 rabbits respectively. Male or female is not restricted, weight varies between 2 and 3 kg . A group,in which the LAD of rabbits was not occluded .B group, in which the rabbits were occluded LAD 15min and followed by 60min ischemic reperfusion. C group, after ligaturing LAD 15min,the rabbits were injected with low dosage( 5ug/kg ) milrinone in vein following by 60min ischemic reperfusion , then each was observed for 60min. In above-mentioned each time point (15min, 30min and 60min) HR, LVDP, LVSP,+DP/DT and -DP/DT were measured and 2ml left ventricle blood was took out to prepare serum specimen for the detection of cTnI, CK, CK-MB, AST ,LDH ,and HBDH. Results There are significant discrepancies ( P ﹤ 0.01 )in hemodynamics indices 15 min, 30 min and 60 min including HR, LVDP ,LVSP , + DP/DT , -DP/DT between C group and B group .CTnI15min 30 min 60 min in C group have significant decline and significant discrepancies ( P ﹤ 0.01 )compared with B group . 15 min, 30 min and 60 min of CK, CK-MB, AST, LDH and HBDH in C Group have obviouse reduction and significant discrepancies ( P ﹤ 0.01 ) compared with B group. Conclusions These results demonstrate that single low dose intravenous injection of milrinone on myocardial stunning in rabbits can increase LVSP, + DP/Dtmax and -DP/Dtmax markedly while LVDP and HR decrease slightly. In other words, single low-dose intravenous injection of milrinone can improve the hemodynamic state significantly in rabbits following with acute myocardial stunning and single low-dose intravenous injection of milrinone on myocardial stunning in rabbits can reduce CK, CK-MB, AST, LDH, HBDH and cTnI obviously. Milrinone not only has positive inotropic function but also has protective function for cardiac muscle. Milrinone not only can be applied to injecting continuously intravenous injection but also single intravenous injection. milrinone not only has therapeutic effect in routine dosage but also has therapeutic effect in low dosage. Single low dosage intravenous injection of milrinone on myocardial stunning play positive role of preserved function in rabbits.