Chronic DOC treatment enhances Na+-H+ exchanger activity of β-intercalated cells in rabbit CCD

Yasuyoshi Yamaji, Matsuhiko Hayashi, Masahiro Iyori, Waichi Kitajima, Takao Saruta

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Abstract

Chronic deoxvcorticosterone (DOC) treatment is known to increase HCO3-secretion in rabbit cortical collecting ducts (CCD). In this study, we examined whether changes in number or function of intercalated cells (ICC) are induced by DOC treatment. The number of total ICC [acetoxymethyl ester of 2′,7′-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein (BCECF/AM)-positive cells after its luminal loading], and β-ICC (peanut agglutinin-positive cells) was not different between DOC and control groups in either initial CCD or terminal CCD. To evaluate the single-cell function of ICC, the rate of intracellular pH (pHi) recovery (dpHi/dt, pHU/s × 103) after NH4+/NH3 prepulse was studied in the in vitro microperfused CCD in the presence of HCO3-/CO2 with BCECP/AM. The mean rate of dpHi/dt of β-ICC in the DOC group was faster than that in the control group (6.19 ± 0.36 vs. 4.30 ± 0.41, P < 0.005, respectively), whereas baseline pHi and buffer capacity were similar in the two groups. The inhibition of basolateral Na+-H+ exchanger with 1 mM amiloride eliminated the difference of dpHi/dt between the two groups, indicating the increased activity of basolateral Na+-H+ exchanger of β-ICC in the DOC group. The correction of DOC-induced metabolic alkalosis by oral acid loading abolished the increase in Na+/H+ exchanger activity by chronic DOC treatment. These results suggest that DOC treatment induces a functional change in a single β-ICC and that this functional change was induced by in vivo acid-base status.

Original languageEnglish
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume262
Issue number5 31-5
Publication statusPublished - 1992

Fingerprint

Sodium-Hydrogen Antiporter
Rabbits
Peanut Agglutinin
Alkalosis
Control Groups
Acids
Amiloride
Fluorescein
Buffers
Esters

Keywords

  • Intracellular pH
  • Metabolic acidosis
  • Metabolic alkalosis
  • Microperfusion
  • Sodium-proton exchanger

ASJC Scopus subject areas

  • Physiology

Cite this

Chronic DOC treatment enhances Na+-H+ exchanger activity of β-intercalated cells in rabbit CCD. / Yamaji, Yasuyoshi; Hayashi, Matsuhiko; Iyori, Masahiro; Kitajima, Waichi; Saruta, Takao.

In: American Journal of Physiology - Renal Fluid and Electrolyte Physiology, Vol. 262, No. 5 31-5, 1992.

Research output: Contribution to journalArticle

Yamaji, Yasuyoshi ; Hayashi, Matsuhiko ; Iyori, Masahiro ; Kitajima, Waichi ; Saruta, Takao. / Chronic DOC treatment enhances Na+-H+ exchanger activity of β-intercalated cells in rabbit CCD. In: American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 1992 ; Vol. 262, No. 5 31-5.
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AU - Iyori, Masahiro

AU - Kitajima, Waichi

AU - Saruta, Takao

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N2 - Chronic deoxvcorticosterone (DOC) treatment is known to increase HCO3-secretion in rabbit cortical collecting ducts (CCD). In this study, we examined whether changes in number or function of intercalated cells (ICC) are induced by DOC treatment. The number of total ICC [acetoxymethyl ester of 2′,7′-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein (BCECF/AM)-positive cells after its luminal loading], and β-ICC (peanut agglutinin-positive cells) was not different between DOC and control groups in either initial CCD or terminal CCD. To evaluate the single-cell function of ICC, the rate of intracellular pH (pHi) recovery (dpHi/dt, pHU/s × 103) after NH4+/NH3 prepulse was studied in the in vitro microperfused CCD in the presence of HCO3-/CO2 with BCECP/AM. The mean rate of dpHi/dt of β-ICC in the DOC group was faster than that in the control group (6.19 ± 0.36 vs. 4.30 ± 0.41, P < 0.005, respectively), whereas baseline pHi and buffer capacity were similar in the two groups. The inhibition of basolateral Na+-H+ exchanger with 1 mM amiloride eliminated the difference of dpHi/dt between the two groups, indicating the increased activity of basolateral Na+-H+ exchanger of β-ICC in the DOC group. The correction of DOC-induced metabolic alkalosis by oral acid loading abolished the increase in Na+/H+ exchanger activity by chronic DOC treatment. These results suggest that DOC treatment induces a functional change in a single β-ICC and that this functional change was induced by in vivo acid-base status.

AB - Chronic deoxvcorticosterone (DOC) treatment is known to increase HCO3-secretion in rabbit cortical collecting ducts (CCD). In this study, we examined whether changes in number or function of intercalated cells (ICC) are induced by DOC treatment. The number of total ICC [acetoxymethyl ester of 2′,7′-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein (BCECF/AM)-positive cells after its luminal loading], and β-ICC (peanut agglutinin-positive cells) was not different between DOC and control groups in either initial CCD or terminal CCD. To evaluate the single-cell function of ICC, the rate of intracellular pH (pHi) recovery (dpHi/dt, pHU/s × 103) after NH4+/NH3 prepulse was studied in the in vitro microperfused CCD in the presence of HCO3-/CO2 with BCECP/AM. The mean rate of dpHi/dt of β-ICC in the DOC group was faster than that in the control group (6.19 ± 0.36 vs. 4.30 ± 0.41, P < 0.005, respectively), whereas baseline pHi and buffer capacity were similar in the two groups. The inhibition of basolateral Na+-H+ exchanger with 1 mM amiloride eliminated the difference of dpHi/dt between the two groups, indicating the increased activity of basolateral Na+-H+ exchanger of β-ICC in the DOC group. The correction of DOC-induced metabolic alkalosis by oral acid loading abolished the increase in Na+/H+ exchanger activity by chronic DOC treatment. These results suggest that DOC treatment induces a functional change in a single β-ICC and that this functional change was induced by in vivo acid-base status.

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