β_2-肾上腺素能受体过表达后成年犬心肌细胞收缩功能的改变及机制

Changes in contractile function of cardiocytes following overexpressing beta 2 adrenergic receptor in canines and the underlying mechanisms

背景:在转基因小鼠、大鼠等小动物实验中发现,心肌细胞特异性过表达β-肾上腺素受体可以改善其收缩功能,但目前尚缺乏在大型哺乳动物进行的有关实验报道。目的:探讨犬心肌细胞过表达β2-肾上腺素受体后心肌细胞收缩功能的改变及其可能机制。方法:采用胶原酶消化法分离培养犬心肌细胞,用携带β2-肾上腺素受体目的基因的重组腺病毒转染心肌细胞。转染48h后观察心肌细胞β2-肾上腺素受体蛋白表达及在基础状态和最大收缩状态下(以异丙肾上腺素10-6mol/L刺激)心肌细胞cAMP水平及收缩功能的变化。结果与结论:转染β2-肾上腺素受体的心肌细胞β2-肾上腺素受体蛋白表达及胞内cAMP水平明显增多(P<0.05),基础状态下收缩功能明显增强,但不改变最大收缩幅度百分比。说明β2-肾上腺素受体的过表达可能通过增加心肌细胞内cAMP水平改善心肌细胞的收缩功能。

BACKGROUND：Previous studies have found that cardiocytes overexpressing β-adrenergic receptors（β-AR） can improve its contractile function in transgenic mice,rats and other small animals,but experimental reports about the large mammals are few.OBJECTIVE：To observe changes and mechanisms of contractile function following cardiocytes overexpressing β2-AR in canines.METHODS：Canine cardiocytes were isolated by collagenase II and transfected by adenovirus β2AR.The expression of β2AR protein of cardiocytes,the level of intracellular cyclic adenosine monophosphate（cAMP） at basic state and maximum systolic states,and the changes of contractile function were observed at 48 hours after operation.RESULTS AND CONCLUSION：Compared with the control group,the expression of β2AR protein of cardiocytes and the level of the intracellular cAMP in the adenovirus β2AR group were increased（P 0.05）.The basal contraction amplitude of cadiocytes in adenovirus β2-AR group was also increased significantly（P 0.05）,but the max contraction amplitude of cardiocytes was not changed significantly between two groups.The study suggested that the over-expression of β2AR could increase the level of intracellular cAMP and improved the contractile function of cadiocytes in canines.