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心脏起搏点发生自动节律的原理可能与窦房结细胞内贮存的儿茶酚胺(CA)的周期性释放有关。当起搏细胞含CA的囊泡释放时,CA即可进入起搏点细胞间隙并激活细胞膜上的腺苷酸环化酶,进而促进细胞内环-磷酸腺苷的生成,后者可激活蛋白激酶,使膜蛋白发生磷酸化,继之使钙通道开放,于是Ca~(2+)即进入细胞内引起起搏细胞发生除极,从而发动一次心搏活动。在这一过程的同时,起搏细胞内的另一种环核苷酸(环-磷酸鸟苷)也相应地发生周期变化,两种环核苷酸共同调节着膜蛋白的磷酸化与去磷酸化过程。对心搏起点自律性原理的探讨,可能有助于我们弄清和控制心律失常。
The principle of automatic rhythm in cardiac pacemakers may be related to the periodic release of catecholamine (CA) stored in the sinoatrial node cells. When the pacemaker cells containing CA release of vesicles, CA can enter the pacemaker cell gap and activate the adenylyl cyclase on the cell membrane, thereby promoting the formation of intracellular cyclic adenosine monophosphate, the latter activator protein Kinase, phosphorylation of membrane protein, followed by the opening of calcium channels, so that Ca ~ (2+) into the cell caused by pacemaker cell depolarization, thus initiating a cardiac activity. Simultaneously with this process, another cyclic nucleotide (cyclic-guanosine monophosphate) within the pacemaker cells also undergoes periodic changes correspondingly. Both cyclic nucleotides co-regulate the phosphorylation and dephosphorylation of membrane proteins Process. Discussion of the principle of self-discipline of aspirations may help us to understand and control arrhythmias.