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Titolo:
DIETARY HCO3 REDUCES DISTAL TUBULE ACIDIFICATION BY INCREASING CELLULAR HCO3 SECRETION
Autore:
WESSON DE;
Indirizzi:
TEXAS TECH UNIV,HLTH SCI CTR,RENAL SECT,3601 4TH ST LUBBOCK TX 79430 BAYLOR COLL MED,VET AFFAIRS MED CTR HOUSTON TX 77030
Titolo Testata:
American journal of physiology. Renal, fluid and electrolyte physiology
fascicolo: 1, volume: 40, anno: 1996,
pagine: 132 - 142
SICI:
0363-6127(1996)40:1<132:DHRDTA>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
RENAL BICARBONATE REABSORPTION; CORTICAL COLLECTING DUCT; CARBONIC-ANHYDRASE; RAT-KIDNEY; PROXIMAL ACIDIFICATION; METABOLIC ALKALOSIS; H+-SECRETION; INVIVO; NEPHRON; TRANSPORT;
Keywords:
ACETAZOLAMIDE; ALKALI; CHLORIDE; MICROPUNCTURE; SODIUM; SULFATE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
D.E. Wesson, "DIETARY HCO3 REDUCES DISTAL TUBULE ACIDIFICATION BY INCREASING CELLULAR HCO3 SECRETION", American journal of physiology. Renal, fluid and electrolyte physiology, 40(1), 1996, pp. 132-142

Abstract

We examined the components of net HCO3 reabsorption (H+/HCO3 secretion and transepithelial HCO3 permeability) in in vivo perfused distal tubules of anesthetized rats to determine the mechanisms by which dietary HCO3 reduces acidification in this nephron segment. Animals eating aminimum electrolyte diet drank either (in mM) 80 NaHCO3, 80 NaCl, or 40 Na2SO4 for 7-10 days and were compared with controls drinking distilled H2O. On perfusion with a HCO3- and Cl--containing solution, net HCO3 reabsorption was lower than control in only the NaHCO3 animals (14.4 +/- 1.3 vs. 4.1 +/- 0.5 pmol . mm(-1). min(-1), P < 0.001). On perfusion with a 0 HCO3-0 Cl- solution, distal tubule luminal HCO3 accumulation (J(HCO3)) was higher in NaHCO3 animals than control (-13.7 +/- 1.3 vs. -4.7 +/- 0.7 pmol . mm(-1). min(-1), P < 0.002). Despite a higher J(HCO3), estimated transepithelial HCO3 permeability in the NaHCO3 animals was similar to control [0.52 +/- 0.06 vs. 0.36 +/- 0.04 x 10(-7) cm(2)/s, P = not significant (NS)]. Luminal acetazolamide (At) reduced J(HCO3) in NaHCO3 animals to a level similar to control (-6.2 +/- 0.6 vs. -4.0 +/- 0.5 pmol . mm(-1). min(-1), P = NS) in this nephron segment containing cells with cytoplasmic but no luminal carbonic anhydrase activity. Including Cl- in the initial perfusate increased J,co, in NaHCO3 animals only (-20.8 +/- 1.9 vs. -13.7 +/- 1.3 pmol . mm(-1).min(-1), P < 0.02), and this increase was inhibited by luminal Az. Calculated H+ secretion was similar among groups. Together, the data indicate that dietary HCO3 reduces distal tubule acidification by increasing Az-sensitive generation of HCO3 by distal tubule cells that entersthe lumen by a mechanism augmented by luminal Cl-.

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Documento generato il 01/10/20 alle ore 16:09:35