管腔和肾小管周围HCO3(-)浓度及PCO2对体外灌注的兔近端曲管中HCO3(-)重吸收的影响。
Effect of luminal and peritubular HCO3(-) concentrations and PCO2 on HCO3(-) reabsorption in rabbit proximal convoluted tubules perfused in vitro.
作者信息
Sasaki S, Berry C A, Rector F C
出版信息
J Clin Invest. 1982 Sep;70(3):639-49. doi: 10.1172/jci110658.
The effect of luminal and peritubular HCO3(-) concentrations and PCO2 on HCO3(-) reabsorption was examined in rabbit proximal convoluted tubules perfused in vitro. Increasing luminal HCO3(-) concentration from 25 to 40 mM without changing either peritubular HCO3(-) concentration or PCO2, stimulated HCO3(-) reabsorption by 41%. When luminal HCO3(-) concentration was constant at 40 mM and peritubular HCO3(-) concentration was increased from 25 to 40 mM without changing peritubular PCO2, a 45% reduction in HCO3(-) reabsorption was observed. This inhibitory effect of increasing peritubular HCO3(-) concentration was reversed when peritubular pH was normalized by increasing PCO2. Passive permeability for HCO3(-) was also measured and found to be 1.09 +/- 0.17 X 10(-7) cm2 s-1. Using this value, the passive flux of HCO3(-) could be calculated. Only a small portion (less than 23%) of the observed changes in net HCO3(-) reabsorption can be explained by the passive HCO3(-) flux. We conclude that luminal and peritubular HCO3(-) concentrations after HCO3(-) reabsorption by changing the active H+ secretion rate. Analysis of these data suggest that both luminal and peritubular pH are major determinants of HCO3(-) reabsorption.
在体外灌注的兔近端曲管中，研究了管腔和肾小管周围HCO₃⁻浓度及PCO₂对HCO₃⁻重吸收的影响。在不改变肾小管周围HCO₃⁻浓度或PCO₂的情况下，将管腔HCO₃⁻浓度从25 mM增加到40 mM，可使HCO₃⁻重吸收增加41%。当管腔HCO₃⁻浓度恒定在40 mM，且肾小管周围HCO₃⁻浓度从25 mM增加到40 mM而不改变肾小管周围PCO₂时，观察到HCO₃⁻重吸收减少45%。当通过增加PCO₂使肾小管周围pH正常化时，增加肾小管周围HCO₃⁻浓度的这种抑制作用被逆转。还测量了HCO₃⁻的被动通透性，发现其为1.09±0.17×10⁻⁷ cm² s⁻¹。利用该值，可以计算出HCO₃⁻的被动通量。观察到的净HCO₃⁻重吸收变化中，只有一小部分（不到23%）可以用HCO₃⁻的被动通量来解释。我们得出结论，管腔和肾小管周围HCO₃⁻浓度通过改变活性H⁺分泌速率来影响HCO₃⁻重吸收。对这些数据的分析表明，管腔和肾小管周围pH都是HCO₃⁻重吸收的主要决定因素。
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