Evidence for apical sodium proton exchange in macula densa cells.

Academic Article

Abstract

  • These studies were performed to determine if changes in luminal sodium chloride concentration ([NaCl]) might alter macula densa intracellular pH. Isolated thick ascending limbs with attached glomeruli were bathed in a 150 mM NaCl Ringer's solution and perfused in vitro with a 25 mM NaCl solution; N-methyl-D-glucamine cyclamate was used to substitute for NaCl. Macula densa cells were loaded with BCECF and intracellular pH was monitored using a microscope based-dual excitation photometer system. Control intracellular pH for all experiments in which tubules were initially perfused with 25 mM NaCl averaged 7.22 +/- 0.06; N = 28. Increasing luminal [NaCl] from 25 to 150 mM elevated macula densa pH by 0.15 +/- 0.03 (N = 6; P < 0.05) while increasing just luminal [Na] from 25 to 150 mM alkalinized macula densa cells by 0.17 +/- 0.05 (N = 6; P < 0.05). In addition, there was a highly significant linear relationship between luminal [Na] and intracellular pH between 25 and 150 mM NaCl. Other studies were performed to assess the effects of amiloride, an inhibitor of Na:H exchange, on macula densa intracellular pH. Addition of amiloride, to the 25 mM NaCl perfusate acidified macula densa cells by 0.09 +/- 0.03 (N = 6; P < 0.001) and significantly attenuated the increase in pH obtained when luminal [NaCl] was raised from 25 to 150 mM. Other studies evaluated the effects of inhibition of Na:2Cl:K cotransport on macula densa pH.(ABSTRACT TRUNCATED AT 250 WORDS)
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    Published In

    Keywords

  • Amiloride, Animals, Chlorides, Female, Fluorescent Dyes, Hydrogen-Ion Concentration, Intracellular Fluid, Ion Transport, Kidney Tubules, Distal, Microscopy, Fluorescence, Rabbits, Sodium, Sodium Chloride, Sodium-Hydrogen Exchangers
  • Pubmed Id

  • 22909825
  • Authorlist

  • Fowler BC; Chang YS; Laamarti A; Higdon M; Lapointe JY; Bell PD
  • Start Page

  • 746
  • End Page

  • 751
  • Volume

  • 47
  • Issue

  • 3