Influence of cyclic AMP on intracellular pH regulation and chloride fluxes in barnacle muscle fibres
Influence of cyclic AMP on intracellular pH regulation and chloride fluxes in barnacle muscle fibres
复制标题
环AMP对藤壶肌纤维细胞内pH调节和氯通量的影响
作者：
W. Boron;J. Russell;M. Brodwick;D. W. Keifer;A. Roos
许多细胞内过程的pH敏感性需要内部pH（pHi）的密切调节。由于许多细胞的pHi维持在比H+在细胞膜上平衡时更高的值，因此细胞代谢和被动H+流入和HCO−3流出的酸化效应必须通过主动酸排出来平衡。现在人们普遍认为，这种挤出是由pHi的降低刺激的，在一些细胞中，它是通过将外部HCO−3交换为内部Cl−来实现的（参考文献1-4）。最近，通过观察到双丁酰环磷酸腺苷减弱哺乳动物心肌中CO2诱导的pHi下降，提出了环磷酸腺苷（环AMP）在pHi调节中的作用5。我们现在报告的实验是关于环腺苷酸对藤壶肌肉纤维中酸排出和伴随的Cl−通量的影响，这种制备物已知含有环腺苷酸（参考文献6）。我们的数据表明，内部应用的环AMP增强了pH调节系统对酸负荷的响应。
THE pH sensitivity of numerous intracellular processes requires the close regulation of internal pH (pHi). As the pHi of many cells is maintained at a higher value than it would have if H+ were at equilibrium across the cell membrane, it follows that the acidifying effects of cellular metabolism and of passive H+ influx and HCO−3 efflux must be balanced by active acid extrusion. It is now generally accepted that this extrusion is stimulated by decreases in pHi, and that, in several cells, it is accomplished by exchanging external HCO−3 for internal Cl− (refs 1–4). Recently, a role for cyclic 3′,5′-adenosine monophosphate (cyclic AMP) in pHi regulation was suggested by the observation that dibutyryl cyclic AMP attenuates the CO2-induced fall of pHi in mammalian cardiac muscle5. We now report experiments on the effects of cyclic AMP on acid extrusion and on accompanying Cl− fluxes in the barnacle muscle fibre, a preparation known to contain cyclic AMP (ref. 6). Our data show that internally applied cyclic AMP enhances the response of the pHi-regulating system to acid loads.