{'fraction_non_alphanumeric': 0.05951506245407789, 'fraction_numerical': 0.05290227773695812, 'mean_word_length': 3.778947368421053, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Intracellular pH in the isolated perfused rabbit proximal straight tubule.

For the purpose of measuring the intracellular pH (pHi) of the mammalian renal proximal tubule, a liquid membrane pH microelectrode was made using a neutral hydrogen ion-selective carrier. The pHi of the rabbit proximal straight tubule perfused in vitro with a solution containing 25 mM HCO3- was 7.22 +/- 0.03. We noted a value significantly lower than the bath pH of 7.44 +/- 0.02 but significantly higher than the pHi of 6.62 +/- 0.03 predicted for passive H+ distribution. Replacement of luminal Na+ with choline quickly (within 1 min) decreased pHi from 7.25 +/- 0.05 to 7.10 +/- 0.05 (P less than 0.001). This change was reversible when Na+ was added again in the luminal solution. A reduction of luminal Na+ from 20 mM to 0 also reduced pHi from 7.15 +/- 0.06 to 7.04 +/- 0.08, and this pHi reduction was blocked by luminal addition of 1 mM amiloride. However, pHi reduction induced by luminal Na+ removal was not affected by luminal addition of 1 mM SITS. Replacement of bath Na+ with choline also reversibly reduced pHi from 7.27 +/- 0.02 to 7.15 +/- 0.02 (P less than 0.001), but this change was totally blocked by the presence of 1 mM SITS. Accordingly, these data suggest that a Na+-H+ exchanger exists in the luminal membrane of the intact rabbit proximal straight tubule.