Premium
Analysis of H,K‐ATPase‐mediated acid secretion along the mouse collecting duct
Author(s) -
Lynch Irma Jeanette,
Rudin Alicia,
Xia Shenling,
Wingo Charles S.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.1012.3
Subject(s) - bafilomycin , chemistry , ouabain , intracellular ph , reabsorption , atpase , secretion , microbiology and biotechnology , intracellular , biochemistry , enzyme , sodium , biology , apoptosis , organic chemistry , autophagy
In the collecting duct (CD), the H,K‐ATPases function in cation reabsorption and H secretion. The purpose of this study was to evaluate H,K‐ATPase‐mediated H secretion along the CD. Intracellular pH (pH i ) recovery to acute H loading was investigated in 1) common CD cell lines and 2) in the microperfused cortical, outer medullary, and inner medullary CD (CCD, OMCD, IMCD). pH i recovery rates (U/min) were greatest in the OMCD 1 cell line (0.25 ± 0.01), followed by mpk‐CCD c14 (0.17 ± 0.01), mIMCD‐K2 (0.12 ± 0.01), and mIMCD‐3 (0.06 ± 0.02) cells. Na,H‐exchange inhibition (EIPA) diminished the majority of pH i recovery in these cells (65%, 97%, 74%, and 90%, respectively). In OMCD 1 , where EIPA‐insensitive pH i recovery was greatest, H,K‐ATPase activity was 0.10 ± 0.01 measured as EIPA‐ and bafilomycin A 1 (H‐ATPase inhibitor)‐insensitive (EBI) pH i recovery. Sch28080 (HKa 1 inhibitor) significantly inhibited this recovery by 84%. EBI pH i recovery was greatest in the microperfused CCD (0.10 ± 0.02) then in OMCD (0.04 ±0.01) and was minimal in IMCD (0.01 ± 0.00). EBI pH i recovery was 0.30 ± 0.03 and 0.26 ± 0.03 in A‐ and B‐type ICs and was Sch28080 or ouabain (HKα 2 inhibitor) sensitive. These data suggest: 1) H,K‐ATPase mediated H secretion is greatest in the CCD, 2) both A‐ and B‐type ICs possess HKα 1 and HKα 2 H,K‐ATPase isoforms, and 3) the OMCD 1 cell line best exhibits H,K‐ATPase activity. This work was funded by NIH Grant R01‐DK‐049750.