Title: Experimental Study of β-adrenergic Receptor Channel in Ischemia-reperfusion Injury in Aged Myocardium
Abstract: Objective To study β adrenergic receptor channel in experimental ischemia reperfusion injury in aged myocardium.Methods Twenty dogs(15~20 kg) were randomly divided into two groups:group A (young,3~4years old, n =10) ,group B (old,7~8 years old, n =10).All the dogs were anaesthetized firstly then followed 60 minutes of global ischemia and 30 minutes of reperfusion under cardiopulmonary bypass (CPB).During this time,a vent was inserted through the left ventricular apex,from which LVEDP?+dp/dt? dp/dt and ECG Were measured by using MPA 2000 bio signal analytical system.Myocardial specimens were collected at the beginning of reperfusion,30 min after reperfusion and 60 min after reperfusion.Myocardium were prepared for measureing the density of β adrenergic receptor,G protein level,cAMP and AC activity.Results (1) Group B had higher LVEDP but lower +dp/dt max and dp/dt max than group A at each stage.After CPB,LVEDP showed no difference before and after surgery in either group ,while decrease of +dp/dt max and dp/dt max were found in both group A and group B,more significant in group B.(2) The density of β adrenergic receptor was decreased at the beginning of reperfusion and increased at 60 min after reperfusion in both groups.The recovery speed of the density in group B was slower than that in group A.(3) There was no significant difference in Gs before and after surgery in group A.Compared with group B,the level of Gi decreased significantly after the reperfusion in group A.There were decrease in Gs and Gi after reperfusion in group B,more greatly in the former.The ratio of Gi/Gs in group B was greatly higher than that in group A.(4) Compared with group A,the AC activity and cAMP decreased more significantly in group B.Conclusion After cardiac surgery in the old,the increase of β adrenergic receptor density was less than that in the young,the ratio of Gi/Gs was greatly higher than the young,hence aggravate the ischemia reperfusion injury in old myocardium.
Publication Year: 2004
Publication Date: 2004-01-01
Language: en
Type: article
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