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In vivo microelectrode assessment of NBCe2 activity in the distal nephron during an acid load (1122.2)
Author(s) -
Yuan yang,
Li huaqing,
Wen Donghai,
Boettger Thomas,
Sansom Steven
Publication year - 2014
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.28.1_supplement.1122.2
Subject(s) - reabsorption , nephron , microelectrode , cotransporter , chemistry , bicarbonate , in vivo , endocrinology , medicine , transepithelial potential difference , biophysics , tubule , proximal tubule , sodium , ion transporter , kidney , biochemistry , renal function , electrode , biology , microbiology and biotechnology , organic chemistry , membrane
The electrogenic Na bicarbonate co‐transporter (NBCe2) reabsorbs one Na and two or three bicarbonates in the distal nephron but its electrogenic function has not been demonstrated in‐vivo . Micropuncture was used to determine the transepithelial potential (Vte) in the distal convoluted tubule 2 (DCT2) of wild type mice (WT) and mice with a knock‐out of NBCe2 (NBCe2‐/‐). The DCT2 is the segment where expression of ENaC‐mediated Na reabsorption and ROMK‐mediated K secretion begins. Fine tip microelectrodes were placed in the lumen of the DCT2. A ground reference electrode was placed in the surface saline solution near the luminal microelectrode. Each group: n 蠅 3. We validated the microelectrode measurements by determining the effects on Vte of proximal tubule in control (‐5.6 ± 0.3 mV) and after giving 2% IP phloridzin (Vte = ‐0.2 ± 0.2 mV), an inhibitor of Na‐glucose cotransport. The Vte of the DCT2 was ‐11.0 ± 0.6 mV in WT control diet mice. When treated with acidic (280 mM NH 4 Cl) drinking water, the Vte of WT decreased to 0.4 ± 1.1 mV, a value significantly greater than WT, consistent with H+ secretion and/or bicarbonate reabsorption in this segment. When treated with acid water, the Vte of NBCe2‐/‐ was ‐3.4 ± 0.3 mV, a value significantly less than that of WT on acid water. We conclude that the NBCe2 is located in the DCT2 where it contributes to a more positive luminal potential when mice consume an acid load. Grant Funding Source : NIDDK