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

doi:10.1152/ajpheart.1997.272.5.h2164

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

Research output: Contribution to journal › Article › peer-review

56 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 language	English
Pages (from-to)	H2164-H2172
Journal	American Journal of Physiology - Heart and Circulatory Physiology
Volume	272
Issue number	5 41-5
DOIs	https://doi.org/10.1152/ajpheart.1997.272.5.h2164
Publication status	Published - 1997
Externally published	Yes

Keywords

exchange current
excitation-contraction coupling
patch clamp

ASJC Scopus subject areas

Physiology
Cardiology and Cardiovascular Medicine
Physiology (medical)

Access to Document

10.1152/ajpheart.1997.272.5.h2164

Cite this

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

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%.",

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T1 - Inhibition by external Cd2+ of Na/Ca exchange and L-type Ca channel in rabbit ventricular myocytes

AU - Hobai, Ion A.

AU - Bates, Jenny A.

AU - Howarth, F. Chris

AU - Levi, Allan J.

PY - 1997

Y1 - 1997

N2 - 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%.

AB - 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%.

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