Sodium-dependent bicarbonate absorption by cortical thick ascending limb of rat kidney.

Research output: Contribution to journalArticle

Abstract

In vitro microperfusion experiments were performed to investigate the mechanism of bicarbonate absorption in the cortical thick ascending limb of the rat. Tubules were perfused at 1.0-1.5 nl X min-1 X mm-1 and bicarbonate concentration was 25 mM in the perfusate and bath. Bicarbonate absorption rates were determined by microcalorimetry. Control tubules absorbed bicarbonate at a mean rate of 9.5 +/- 0.6 pmol X min-1 X mm-1. The limiting luminal bicarbonate concentration was approximately 5 mM for tubules perfused at slow rates with 25 mM bicarbonate in the bath. Acetazolamide (10(-4)M) in the bath reduced bicarbonate absorption by 76% without significant effect on transepithelial voltage. Removing sodium from the perfusate and bath or removing potassium from the bath reduced bicarbonate absorption and transepithelial voltage to near zero. Adding amiloride (5 X 10(-4) or 10(-3) M) to the perfusate reduced bicarbonate absorption by 60-75% without detectable effect on transepithelial voltage. Adding furosemide (10(-4)M) to the perfusate increased bicarbonate absorption significantly by 40-50% while decreasing transepithelial voltage from 17 to 1.8 mV. Thus, bicarbonate absorption by cortical thick ascending limbs requires carbonic anhydrase activity and sodium transport but is not dependent on transepithelial voltage. When considered together, the results are consistent with mediation of the bicarbonate absorption by apical membrane sodium-hydrogen exchange.

Original languageEnglish (US)
JournalThe American journal of physiology
Volume248
Issue number6 Pt 2
StatePublished - Jun 1985
Externally publishedYes

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Sodium Bicarbonate
Bicarbonates
Extremities
Kidney
Baths
Sodium
Acetazolamide
Carbonic Anhydrases
Amiloride
Furosemide
Hydrogen
Potassium

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Sodium-dependent bicarbonate absorption by cortical thick ascending limb of rat kidney. / Good, David.

In: The American journal of physiology, Vol. 248, No. 6 Pt 2, 06.1985.

Research output: Contribution to journalArticle

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