Cytochrome P-450 arachidonate metabolites affect ion fluxes in rabbit medullary thick ascending limb

B. Escalante, D. Erlij, J R Falck, J. C. McGiff

Research output: Contribution to journalArticle

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Abstract

The medullary thick ascending limb of Henle's loop (mTALH) of the rabbit metabolizes arachidonic acid (AA) via a cytochrome P-450 (P-450) monooxygenase pathway to several products, of which the principal are 20- hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) and 1,20- eicosatetraenedioic acid (20-COOH-AA). To understand their mechanism of action on alkali cation metabolism in mTALH cells, we have compared their effects with those of ouabain and furosemide. Incubation of rabbit isolated mTALH cells with either 1 mM ouabain or furosemide decreased K+ content from a control of 1,015 ± 51 peq/μg protein to 717 ± 41 and to 548 ± 48 peq/μg protein, respectively, whereas they had opposite effects on Na+ content; from a control of 138 ± 22 peq/μg protein, ouabain increased Na+ content to 357 ± 37 peq/μg protein, and furosemide decreased it to 64 ± 23 peq/μg protein. Preincubation with either 20-HETE (1 μM) or 20-COOH-AA (1 μM) decreased Na+ and K+, resembling furosemide in their effects on Na+ and K+ content. In other experiments we used monensin-treated cells to determine 86Rb uptake under conditions in which Na+ entry into the cell was not rate limiting. Under these conditions ouabain still inhibited 86Rb uptake, and the effect of AA was blocked. A major action of AA metabolites on Na+-K+-adenosinetriphosphatase was thereby excluded. Furthermore, AA metabolites did not inhibit Ba2+-sensitive 86Rb efflux, indicating that they do not act through K+ channels. We conclude that these P-450-AA metabolites have a furosemide-like effect; namely, they act principally to inhibit the Na+-K+-2Cl- cotransporter of the mTALH cells.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume266
Issue number6 35-6
StatePublished - 1994

Fingerprint

Metabolites
Arachidonic Acid
Cytochrome P-450 Enzyme System
Furosemide
Extremities
Loop of Henle
Ions
Fluxes
Rabbits
Ouabain
Proteins
Monensin
Alkalies
Mixed Function Oxygenases
Metabolism
Adenosine Triphosphatases
Cations
Cells
Experiments

Keywords

  • ion transport
  • monensin
  • ouabain
  • potassium efflux
  • sodium- potassium-activated adenosinetriphosphatase
  • sodium-potassium-2-chloride cotransporter

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

Cytochrome P-450 arachidonate metabolites affect ion fluxes in rabbit medullary thick ascending limb. / Escalante, B.; Erlij, D.; Falck, J R; McGiff, J. C.

In: American Journal of Physiology - Cell Physiology, Vol. 266, No. 6 35-6, 1994.

Research output: Contribution to journalArticle

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