Marrannes R, de Hemptinne A, Leusen I
Pflugers Arch. 1981 Mar;389(3):199-209. doi: 10.1007/BF00584780.
Conduction velocity in isolated rabbit atrial fibers was continuously measured in solutions having a different anionic composition. When 20mmol/l of chloride was replaced by 20 mmol/l lactate or other anions of weak organic acids at constant pH 6.8, biphasic initial transient changes in conduction velocity were observed. The produced transient changes had a greater amplitude with organic acids which have a greater pK and lipid/water partition ratio. The magnitude of the transients was also greater at pH 6.8 than at pH 7.5, and also when the buffering capacity of the superfusion solution was smaller. Measurements of intracellular pH (pHi) in sheep Purkinje fibers and of pH at the surface (pHs) of sheep Purkinje and rabbit atrial fibers with pH sensitive microelectrodes, showed a transient increase of pH and a sustained decrease of pHi on replacement of 20mmol/l chloride by organic anions of weak acids (at constant pH of the superfusion solution). A combined influence of the transient pHs change and the sustained pHi modification seems to be important in the explanation of the biphasic changes in conduction velocity.
在具有不同阴离子组成的溶液中,连续测量分离的兔心房纤维中的传导速度。当在恒定pH 6.8下用20 mmol/l乳酸或其他弱有机酸阴离子替代20 mmol/l氯化物时,观察到传导速度出现双相初始瞬态变化。对于具有更大pK和脂/水分配比的有机酸,所产生的瞬态变化幅度更大。在pH 6.8时瞬变的幅度也大于pH 7.5时,并且当灌流溶液的缓冲能力较小时也是如此。用pH敏感微电极测量绵羊浦肯野纤维的细胞内pH(pHi)以及绵羊浦肯野纤维和兔心房纤维表面的pH(pHs),结果显示,用弱酸有机阴离子替代20 mmol/l氯化物时(在灌流溶液的恒定pH下),pH出现瞬态升高,pHi持续降低。瞬态pHs变化和持续的pHi改变的综合影响似乎对于解释传导速度的双相变化很重要。