| Secretion of HCO3-/OH- in cortical distal tubule of the rat. | |
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MedLine Citation:
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PMID: 7769608 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Secretion of bicarbonate has been described for distal nephron epithelium and attributed to apical Cl-/HCO3- exchange in beta-intercalated cells. We investigated the presence of this mechanism in cortical distal tubules by perfusing these segments with acid (pH 6) 10 mM phosphate Ringer. The kinetics of luminal alkalinization was studied in stationary microperfusion experiments by double-barreled pH (ion-exchange resin)/1 M KCl reference microelectrodes. Luminal alkalinization may be due to influx (into the lumen) of HCO3- or OH-, or efflux of H+. The magnitude of the Cl-/HCO3- exchange component was measured by perfusing the lumen with solutions with or without chloride, which was substituted by gluconate. This component was not different from zero in control and alkalotic (chronic plus acute) Wistar rats. Homozygous Brattleboro rats (BRB), genetically devoid of antidiuretic hormone, were used since this hormone has been shown to stimulate H+ secretion, which could mask bicarbonate secretion. In these rats, no evidence for Cl-/HCO3- exchange was found in control BRB and in early distal segments of alkalotic animals, but in late distal tubule a significant component of 0.14 +/- 0.033 nmol/cm2.sec was observed, which, however, is small when compared to the reabsorptive flow found in control Wistar rats, of 0.95 +/- 0.10 nmol/cm2.sec. In addition, 5 x 10(-4) M SITS had no effect on distal bicarbonate reabsorption in controls as well as on secretion in alkalotic Wistar and Brattleboro rats, which is compatible with the absence of effect of this drug on the apical Cl-/HCO3- exchange in other tissues.(ABSTRACT TRUNCATED AT 250 WORDS) |
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Authors:
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R Fernandez; G Malnic |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of membrane biology Volume: 143 ISSN: 0022-2631 ISO Abbreviation: J. Membr. Biol. Publication Date: 1995 Feb |
Date Detail:
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Created Date: 1995-07-06 Completed Date: 1995-07-06 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0211301 Medline TA: J Membr Biol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 227-35 Citation Subset: IM |
Affiliation:
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Department of Physiology and Biophysics, USP, University of São Paulo, Brazil. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid
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pharmacology Animals Antiporters / metabolism Bicarbonates / metabolism* Chloride-Bicarbonate Antiporters Chlorides / pharmacology Gluconates / pharmacology Hydroxides / metabolism* Kidney Cortex / metabolism* Kidney Tubules, Distal / metabolism* Male Perfusion Rats Rats, Brattleboro Rats, Wistar |
| Chemical | |
Reg. No./Substance:
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0/Antiporters; 0/Bicarbonates; 0/Chloride-Bicarbonate Antiporters; 0/Chlorides; 0/Gluconates; 0/Hydroxides; 27816-59-7/4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid |
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