The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids

Marisa L Zallocchi, Pilar Igarreta, Juan Carlos Calvo, Nancy Amaral Reboucas, María Cristina Damasco

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Background: Previously we showed that corticosterone and aldosterone increased proton fluxes in proximal tubule, by micropuncture and stationary microperfusion. Since the Na+/H+ exchanger is responsible for the main proximal proton secretion, we have now evaluated the effects aldosterone on Na+/H+ exchange activity in brush border vesicles. In order to evaluate the mechanism of action of glucocorticoids and mineralocorticoids, we studied the comparative effects of corticosterone and aldosterone on the abundance of NHE3 and NHE2 isoforms. Material/Methods: We isolated renal brush border vesicles from rats by differential centrifugation in sham-operated, adrenalectomized, and adrenalectomized-aldosterone treated (ADX + aldosterone) animals. We measured the kinetics of H+ transport in response to increasing concentrations of Sodium Gluconate by fluorimetry using acridine orange. For Na+/H+ exchanger abundance we used Western blot analysis of brush border proteins in the above groups and in adrenalectomized-corticosterone treated rats. Results: The Vmax in adrenalectomized animals was 22,162±1828 fluorescence units/min; in sham animals, 37,020±2722; and in ADX + aldosterone, 42,344±3044 (p<0.01 adrenalectomized vs others). No differences in Km were observed. Adrenalectomy decreased NHE3 abundance over Sham by 32% without modifying NHE2. Corticosterone-replacement enhanced NHE3 abundance by 76% and failed to increase NHE2. Aldosterone enhanced NHE2 abundance by 75% and did not increase NHE3. Conclusion: Mineralocorticoids enhance Na+/H+ exchange activity by increasing NHE2 abundance; glucocorticoids, by increasing NHE3 abundance.

Original languageEnglish (US)
JournalMedical Science Monitor
Volume9
Issue number2
StatePublished - Feb 1 2003

Fingerprint

Sodium-Hydrogen Antiporter
Microvilli
Aldosterone
Adrenal Cortex Hormones
Corticosterone
Mineralocorticoids
Glucocorticoids
Protons
Fluorometry
Acridine Orange
Adrenalectomy
Centrifugation
Punctures
Protein Isoforms
Fluorescence
Western Blotting
Kidney

Keywords

  • Aldosterone
  • Glucocorticoids
  • H transport
  • NHE2
  • NHE3

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Zallocchi, M. L., Igarreta, P., Calvo, J. C., Reboucas, N. A., & Damasco, M. C. (2003). The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids. Medical Science Monitor, 9(2).

The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids. / Zallocchi, Marisa L; Igarreta, Pilar; Calvo, Juan Carlos; Reboucas, Nancy Amaral; Damasco, María Cristina.

In: Medical Science Monitor, Vol. 9, No. 2, 01.02.2003.

Research output: Contribution to journalArticle

Zallocchi, ML, Igarreta, P, Calvo, JC, Reboucas, NA & Damasco, MC 2003, 'The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids', Medical Science Monitor, vol. 9, no. 2.
Zallocchi, Marisa L ; Igarreta, Pilar ; Calvo, Juan Carlos ; Reboucas, Nancy Amaral ; Damasco, María Cristina. / The mechanisms of brush border Na+/H+ exchanger activation by corticosteroids. In: Medical Science Monitor. 2003 ; Vol. 9, No. 2.
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