| PART 1: Establishment of an experimental model of warm ischemic rat heart grafts by heart arrest induced by rapid exsanguinations as well as an experimental model of Langendorff Perfusion.Objective: To establish an experimental model of warm ischemic rat heart grafts by heart arrest induced by rapid exsanguinations as well as an experimental model of Langendorff perfusion, and to study the effect of warm ischemia on the structure and function of the rats heart grafts.Methods: 16 SD rats were divided into 2 groups randomly, the control (n=8) group and warm ischemia (n=8) group. The hearts from warm ischemia group were left in situ for 10min after rapid exsanguinations by transection of AA and IVC. Both two groups underwent routine myocardium protection of cold storage for 4 hours followed by continuous perfusion with Langendorff aparatus for 1 hour. Resuscitation of the heart were observed, the first 10ml of coronary extravagation was collected to detect CK, CK-MB, AST and LDH. The coronary flow was measured. After the heart beating was stable, the heart rate (HR), end-diastolic pressure (EDP), peak intraventricular pressure (Peak), +dp/dt max and -dp/dt max were measured. The hearts were reperfused for 1 hour, and then the hearts were harvested for histopathologic study and to determine the percentage of water content.Results: The resuscitation was better in the control group than in WI group. CK, CK-MB, AST and LDH were significantly higher in WI group than in the control group (P<0.01). Coronary flow and homodynamic values were significantly higher in the control group than in WI group (P<0.05). Percentage of water content was significantly lower in the control group than in WI group (P<0.05). Histopathologic damage was more severe in WI group than in the control group. Conclusions: It is available using the experimental model of warm ischemic rat heart grafts after heart arrest induced by rapid exsanguinations as well as a model of Langendorff perfusion to study the effect of warm ischemia on the structure and function of the rat heart grafts. Warm ischemia of 10mins could make a severe damage to the structure and function of rat heart grafts.PART 2: Myocardial protection effect of warm blood cardioplegia reperfusion on warm ischemic rat heart grafts.Objective: To investigate the myocardial protection effect of warm blood cardioplegia reperfusion on the structure and function of warm ischemic rat heart grafts.Methods: 24 SD rats were divided into 3 groups randomly, the control (A, n=8) group underwent coronary flushing with cold cardioplegia and UW solution followed by simple immersion in cold UW solution for 4h without warm ischemia, routine protection (B, n=8) group underwent the same myocardial protection procedure as A group after warm ischemia of 10min, warm blood cardioplegia reperfusion (C, n=8) group, underwent the same myocardial protection procedure as A and B group after warm ischemia of 10min followed by continuous warm blood cardioplegia reperfusion. After the preservation, Langendorff model was settled, resuscitation of the heart were observed, the first 10ml of coronary extravasations (blood flow from the coronary sinus in C group) was collected to detect CK, CK-MB, AST and LDH. The coronary flow was measured by collection of the coronary extravasations. After the heart beating was stable, an balloon was placed into the left ventricle, and the heart rate (HR), end-diastolic pressure (EDP), peak intraventricular pressure (Peak), +dp/dt max and -dp/dt max were measured. The hearts were reperfused for 1 hour, and then the hearts were harvested for histopathologic study and to determine the percentage of water content.Results The resuscitation was better in A and C group than in B group. CK, CK-MB, AST and LDH were significantly higher in B and C group than in A group (P<0.01). Coronary flow and hemodynamic values were significantly higher in A and C group than in B group (P<0.05) without significant difference between A and C group (P>0.05). Percentage of water content was significantly lower in A group than in B and C group (P<0.05), and it was lower in C group than in B group without significant difference. Histopathologic damage was more severe in B group than in A and C group.Conclusions Warm blood cardioplegia reperfusion may be useful to reduce the ischemia-reperfusion damage in heart grafts from NHBDss and improve the resuscitation and homodynamic performance after reperfusion. |
