Calcium and calcimimetics regulate paracellular Na+ transport in the thin ascending limb of Henle's loop in mouse kidney

Noriko Sugawara, Tetsuji Morimoto, Elnur I. Farajov, Naonori Kumagai, Ulviyya F. Aslanova, Tatemitsu Rai, Shinichi Uchida, Sei Sasaki, Shigeru Tsuchiya, Yoshiaki Kondo

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The effect of Ca2+ and calcimimetics on NaCl transport was investigated in the in vitro isolated microperfused mouse thin ascending limb of Henle's loop. In the presence of a transmural NaCl gradient, the transepithelial diffusional potential was 13.7±0.4 mV (n=17). When the Ca2+ in the bath was increased from 1.5 to 4.5 mM at 37°C, the relative permeability of Na+ to Cl- (P Na /P Cl) estimated from the diffusional voltage deflection due to the transepithelial NaCl gradient (V d) changed from 0.371±0.017 to 0.341±0.015 (n=10, P<0.0001). When the Ca2+ in the lumen was increased from 1.5 to 4.5 mM, the P Na /P Cl decreased from 0.349±0.013 to 0.330±0.013 (n=5, P<0.002). The addition of 0.1 mM neomycin and 0.2 mM gentamicin to the bath or lumen also decreased the P Na /P Cl. The same effect on P Na /P Cl of Ca2+ and calcimimetics occurred in ClC-K1 (kidney-specific chloride channel) knockout mice. The addition of 300 μg/ml protamine to the bath strongly inhibited changes to P Na /P Cl induced by basolateral Ca2+. These data indicate that ambient Ca2+ and calcimimetics inhibit Na+ transport in the thin ascending limb, which is known to occur via the paracellular shunt pathway. Our observations strongly suggest that Ca2+ is involved in the regulation of paracellular Na+ permeability in the thin ascending limbs.

Original languageEnglish
Pages (from-to)197-205
Number of pages9
JournalPflugers Archiv European Journal of Physiology
Volume460
Issue number1
DOIs
Publication statusPublished - 2010 Jun

Keywords

  • Ca ions
  • Chloride channel
  • Kidney
  • Loop of Henle
  • Sodium transport

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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