The Protective Effects Of Exogenous CGRP On Myocardia Ischemia/Reperfusion Injury During Cardiopulmonary Bypass

Objective: To investigate the myocardial protective effects of exogenous CGRP added into cardioplegic solution during myocardial ischemia /reperfusion injury caused by open heart surgery under cardio pulmonary bypass. we observed the hemodynamic change, spontaneously rebeating of the heart, the level of CTnI,the concentration of MDA,the activity of SOD,our study try to interpret the myocardial protecting mechanisms of complement of exogenous CGRP during myocardial ischemia reperfusion injury caused by open heart surgery under cardio pulmonary bypass(CPB).To get a better method to alleviate the myocardial ischemia /reperfusion injury during open-heart surgery with cardiopulmonary bypass. Methods: Twenty patients scheduled for repair of ventricular septal defect (VSD)and atrial septal defect (ASD)were randomly divided into two groups: the CGRP group (n₁=10) received CGRP 0.3μg/kg in cardioplegic solution (15ml/kg),the control group (n₂=10)received saline solution in the same fashion. The methods of CPB and infusion in two groups were the same. Standard ECG lead II,HR ,MAP,CVP, SpO₂,,P_ETCO₂ and the temperature of patient were continuously monitored. Before using medicine in the operating room, we measured the HR, MAP, as baseline. The time of clamping aorta, cardiopulmonary bypass and operating, the spontaneously rebeating of heart and the situation of electrocution defibrillation were recorded.Blood samples were taken from arter after induction(T0),5min after clamping aorta(T1),5min after opening aorta (T2), 30min after opening aorta(T3),4h after termination of cardiopulmonary bypass(T4),24h after termination of cardiopulmonary bypass(T5)for determination of the level of cTnI, the concentration of MDA and the activity of SOD. Results 1 The effect of clinic 1.1 The age and weight of the two groups have no significant difference ( P>0.05 ) .The time of clamping aorta, cardiopulmonary bypass and operating of the two groups have no significant difference(P>0.05). 1.2 The change of hemodynamic: In both groups, HR increased to slowed gradually during reperfusion. HR had no significant difference,5min after reperfusion, the CGRP group compared to the control group, HR was significantly lower in the CGRP group on left point of time of reperfusion compared to those in the control group(P<0.05);In both groups, MAP slowed to increased gradually during reperfusion. MAP had no significant difference, 5min after reperfusion, the CGRP group compared to the control group,MAP was significantly higher in the CGRP group on left point of time of reperfusion compared to those in the control group(P<0.01). 1.3 Rate of the heart spontaneously rebeating in the control group was 70%(Three patients occurred ventricular fibrillation and need electrocution defrillation)while those in the CGRP group was 100%.there was significant difference between the control group and the experiment group(P<0.05). 2 The biochemistry of myocardium 2.1 The change of cTnI level: There was no significant difference between T0 in the two group(sP>0.05).Compared with T0, cTnI level gradually increased, there was significant difference at T1 (P<0.05)and extraordinarily significant difference at T2^T5 (P<0.01)in the control group; cTnI level in the CGRP group gradually increased beginning of T1 and there was extraordinarily significant difference at T2^T5, but cTnI level at T2^T5 was notably lower in the CGRP group than that in the control group (P<0.01). 2.2 The change of MDA concentration: There was no significant difference between T0 in the two groups ( P>0.05 ) .Compared with T0, MDA concentration gradually increased in the two groups, there was extraordinarily significant difference at T1 and T2^T5 in the control group(P<0.01);there was extraordinarily significant different at T2^T5 in the experiment group (P<0.01). MDAconcentration at T2^T5 was notably lower in the experiment group than that in the control group (P<0.01). 2.3 The change of SOD activity: There was no significant difference between T0 in the two groups (P>0.05),compared with T0,the activity of SOD gradually decreased and there was extraordinarily significant different at T2^T4 in the control group(P<0.01).The activity of SOD at T5 returned to the level of T0(P>0.05).At T2^T4 the activity of SOD have significant difference in the CGRP group than that in the control group (P<0.01). Conclusions 1 At myocardial reperfusion,HR was lower in the CGRP group than that in the control group (P<0.05);MAP was notably higher in the CGRP group than that in the control group (P<0.01),Proved CGRP have positive inotropic action and negative chronotropic action. 2 Base on the result of the control group, we can observe that the level of cTnI, and the concentration of MDA gradually increased, the activity of SOD gradually decreased, the occur of arrhythmia .This indicated that myocardium occur serious injury after myocardial ischemia reperfusion. 3 CGRP group can obviously restrain the level of cTnI, and the concentration of MDA gradually increased ,the activity of SOD gradually decreased ,the occur of arrhythmia. This indicated that Exogenous CGRP could alleviate the injury of myocardial cell, lessen the degree of lipid peroxidation,...