Changes of activation and inactivation gating of the transient potassium current of rat pituitary melanotrophs caused by micromolar Cd2+ and Zn2+.

Abstract:

:We studied the effects of Zn2+ and Cd2+ on the behaviour of IK(f), a transient outward potassium current in acutely dissociated melanotrophs of the pars intermedia of the rat pituitary gland. Micromolar concentrations of external Cd2+ or Zn2+ caused parallel and nearly equal rightward shifts along the voltage axis of the activation and steady-state inactivation curves for IK(f). The KD for the half-maximal shift of the activation curve was 278 microM for Cd2+ and 93 microM for Zn2+; the maximal shifts of the activation curve were 32.5 and 34 mV, for Cd2+ and Zn2+, respectively. The times to half-activation and half-inactivation were shifted rightward by 30-60 mV in both 500 microM Cd2+ and 500 microM Zn2+. We suggest that Cd2+ and Zn2+ interact specifically with a binding site on or electrically close to the IK(f) channel and in so doing modify the electric field "seen" by the voltage sensors.

authors

Davidson JL,Kehl SJ

doi

10.1139/y95-005

subject

Has Abstract

pub_date

1995-01-01 00:00:00

pages

36-42

issue

1

eissn

0008-4212

issn

1205-7541

journal_volume

73

pub_type

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