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Titolo:
EFFECT OF BASOLATERAL CO2 HCO3- ON INTRACELLULAR PH REGULATION IN THERABBIT S3 PROXIMAL TUBULE/
Autore:
NAKHOUL NL; CHEN LK; BORON WF;
Indirizzi:
YALE UNIV,SCH MED,DEPT CELLULAR & MOLEC PHYSIOL NEW HAVEN CT 06510 YALE UNIV,SCH MED,DEPT CELLULAR & MOLEC PHYSIOL NEW HAVEN CT 06510
Titolo Testata:
The Journal of general physiology
fascicolo: 6, volume: 102, anno: 1993,
pagine: 1171 - 1205
SICI:
0022-1295(1993)102:6<1171:EOBCHO>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
GLOMERULAR MESANGIAL CELLS; CONVOLUTED TUBULE; MEMBRANE-VESICLES; BICARBONATE TRANSPORT; EXOCYTOTIC INSERTION; CL-HCO3 EXCHANGE; H+-ATPASE; SODIUM; COTRANSPORT; SALAMANDER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
45
Recensione:
Indirizzi per estratti:
Citazione:
N.L. Nakhoul et al., "EFFECT OF BASOLATERAL CO2 HCO3- ON INTRACELLULAR PH REGULATION IN THERABBIT S3 PROXIMAL TUBULE/", The Journal of general physiology, 102(6), 1993, pp. 1171-1205

Abstract

We used the absorbance spectrum of the pH-sensitive dye dimethyl-carboxyfluorescein to monitor intracellular pH (pH(i)) in the isolated perfused S3 segment of the rabbit proximal tubule, and examined the effect on pH(i) of switching from a HEPES to a CO2/HCO3- buffer in the lumen and/or the bath (i.e., basolateral solution). Solutions were titrated to pH 7.40 at 37-degrees-C. With 10 mM acetate present bilaterally (lumen and bath), this causing steady-state pH(i) to be rather high (approximately 7.45), bilaterally switching the buffer from 32 mM HEPES to 5% CO2/25 mM HCO3- caused a sustained fall in pH(i) of approximately0.26. However, with acetate absent bilaterally, this causing steady-state pH(i) to be substantially lower (approximately 6.9), bilaterally switching to CO2/HCO3- caused a transient pH(i) fall (due to the influx of CO2), followed by a sustained rise to a level approximately 0.18 higher than the initial one. The remainder of the experiments was devoted to examining this alkalinization in the absence of acetate. Switching to CO2/HCO3- only in the lumen caused a sustained pH(i) fall of approximately 0.15, whereas switching to CO2/HCO3- only in the bath caused a transient fall followed by a sustained pH(i) increase to approximately 0.26 above the initial value. This basolateral CO2/HCO3--inducedalkalinization was not inhibited by 50 muM DIDS applied shortly afterCO2/HCO3- washout, but was slowed approximately 73% by DIDS applied more than 30 min after CO2/HCO3- washout. The rate was unaffected by 100 muM bilateral acetazolamide, although this drug greatly reduced CO2-induced pH(i) transients. The alkalinization was not blocked by bilateral removal of Na+ per se, but was abolished at pH(i) values below approximately 6.5. The alkalinization was also unaffected by short-term bilateral removal of Cl- or SO4=. Basolateral CO2/HCO3- elicited the usual pH(i) increase even when all solutes were replaced, short or long-term (>45 min), by N-methyl-D-glucammonium/glucuronate (NMDG+/Glr-). Luminal CO2/HCO3- did not elicit a pH(i) increase in NMDG+/Glr-. Although the sustained pH(i) increase elicited by basolateral CO2/HCO3- could be due to a basolateral HCO3- uptake mechanism, net reabsorption of HCO3- by the S3 segment, as well as our ACZ data, suggest instead thatbasolateral CO2/HCO3- elicits the sustained pH(i) increase either by inhibiting an acid-loading process or stimulating acid extrusion across the luminal membrane (e.g., via an H+ pump).

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Documento generato il 01/10/20 alle ore 00:09:46