Effects Of Selective α₂-adrenergic Receptor Agonist On Postresuscitation Cardiac Function In Rabbits

Objective:Postresuscitation myocardial dysfunction contributes to the high fatality rate following successful resuscitation.The purpose of this animal research was to observe the effects of selectiveα₂-adrenergic receptor agonist alpha-methylnorepinephrine (α-MNE) on postresuscitation cardiac function in the rabbit cardiopulmonary resuscitation.Methods:After setting up rabbit model of cardiopulmonary resuscitation,18 rabbits were randomly divided into three groups, group A:operation-control group,only anesthesia,surgery, endotracheal intubation,but was not induced ventricular fibrillation; group B:epinephrine group,administration of the standard dose of epinephrine(30ug/kg) during CPR;group C:α-MNE group, administration ofα-MNE(100ug/kg) during CPR.The left ventricular end-diastolic pressure(LVEDP) and peak first derivative of left ventricular pressure(±dp/dt) were observed.Collecting blood samples at certain time points to measure the concentration of B-type natriuretic peptide(BNP) and cardiac troponin T(cTnT).At 240^th minute after successful resuscitation,killed animals and took myocardium to do light microscopy detection.Results:Compared with group A,the BNP and LVEDP of the remaining two groups gradually increased respectively(P＜0.01),±dp/dt decreased(P＜0.01).Increases of BNP and LVEDP in Group C were less than in Group B(P＜0.05,P＜0.05),whereas±dp/dt in group C were higher than in group B(P＜0.05) at the same stage. Compared with group A,the cTnT of the remaining two groups increased respectively(P＜0.01),and at 240^th minutes reached the peak.Increase of cTnT in group C were less than in Group B(P＜0.05)at the same stage,especially at 60^th minutes.group B and group C were detected myocardial injury under a light microscope, but the myocardial damage of group C were lighter than group B.Conclusion:A-MNE administered immediately during resuscitation improved postresuscitation myocardial dysfunction.It reduced the concentration of BNP and cTnT and alleviated cardiac pathological damage at the early stage of cardiopulmonary resuscitation after CPR from cardiac arrest.