Basolateral regulation of pH(i) in isolated snake renal proximal tubules in presence and absence of bicarbonate

William H. Dantzler, Oscar K. Serrano, Diane E. Abbott, Yung Kyu Kim, Olga H. Brokl

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Intracellular pH (pH(i)) and its basolateral regulation were studied in isolated proximal-proximal and distal-proximal segments of garter snake (Thamnophis spp.) renal tubules with oil-filled lumens in HEPES-buffered and in HEPES-HCO3/--buffered media (pH 7.4 at 25°C). pH(i) was measured with the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6- carboxyfluorescein (BCECF) under resting conditions and in response to NH4Cl pulse. Resting pH(i) (~7.1-7.2) and its response to and rate of recovery (dpH(i)/dt) from an NH4Cl pulse were not affected by the presence or absence of HCO3/- in either segment. Rate of recovery was depressed by Na+ removal in distal-proximal segments only and only in HEPES buffer. It was not affected by removal of Cl- or of both Na+ and Cl- or by reduction in membrane potential through addition of Ba2+ (5 mM) or high K+ (75 mM) in either segment in either HEPES or HEPES-HCO3/- buffer. The Na+/H+ exchange inhibitor ethylisopropylamiloride (EIPA) (100 μM) and the anion exchange inhibitor DIDS (100 μM) reduced dpH(i)/dt in the distal-proximal segments only and only in HEPES-HCO3 buffer. The H+-ATPase inhibitor bafilomycin (1 μM), H+-K+-ATPase and K+/NH4/+ exchange inhibitor Schering 28080 (10-100 μM), organic cation efflux inhibitor tetrapentylammonium (25 μM-20 mM), and K+ channel blocker tetraethylammonium (20 mM) had no effect on dpH(i)/dt in either segment. These data do not clearly support basolateral regulation of pH(i) in snake proximal renal tubules by commonly recognized Na+-dependent or Na+- independent acid or base transporters.

Original languageEnglish (US)
Pages (from-to)R1673-R1681
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume276
Issue number6 45-6
DOIs
StatePublished - Jun 1999

Keywords

  • Ammonium chloride pulse
  • Bafilomycin
  • Buffers
  • Garter snakes
  • Schering 28080
  • Thamnophis spp.

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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