Inhibition by external Cd2+ of Na/Ca exchange and L-type Ca channel in rabbit ventricular myocytes

Ion A. Hobai, Jenny A. Bates, F. Chris Howarth, Allan J. Levi

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75 Citations (Scopus)

Abstract

We investigated the effect of external Cd2+ on the Na/Ca exchange and the L-type Ca channel current (I(Ca,L)) in whole cell patch-clamped rabbit ventricular myocytes at 36°C. After the interfering ion channels and the Na/K pump were blocked, the exchange current was measured as the membrane current that was inhibited by 5 mM nickel. External Cd2+ inhibited Na/Ca exchange with a dissociation constant (K(D) of 320.6 ± 12.4 μM and a Hill coefficient of 1.5 ± 0.09 (n = 13 cells) and I(Ca,L) with a K(D) of 2.14 ± 0.15 μM and a Hill coefficient of 0.74 ± 0.03 (n = 11 cells). We observed some overlap in the Cd2+ concentration that blocked each mechanism. Cd2+ (100-500 μM) is used commonly to block I(Ca,L) completely. However, 100 μM Cd2+ also inhibits 20% of the Na/Ca exchange activity, whereas 500 μM Cd2+ inhibits 60%.

Original languageEnglish
Pages (from-to)H2164-H2172
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume272
Issue number5 41-5
DOIs
Publication statusPublished - 1997
Externally publishedYes

Keywords

  • exchange current
  • excitation-contraction coupling
  • patch clamp

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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