Activation by divalent cations of a Ca2+-activated K+ channel from skeletal muscle membrane
Author
dc.contributor.author
Oberhauser, Andres
Author
dc.contributor.author
Alvarez, Osvaldo
Author
dc.contributor.author
Latorre, Ramón
Admission date
dc.date.accessioned
2019-01-29T14:47:58Z
Available date
dc.date.available
2019-01-29T14:47:58Z
Publication date
dc.date.issued
1988
Cita de ítem
dc.identifier.citation
Journal of General Physiology, Volumen 92, Issue 1, 2018, Pages 67-86
Identifier
dc.identifier.issn
15407748
Identifier
dc.identifier.issn
00221295
Identifier
dc.identifier.other
10.1085/jgp.92.1.67
Identifier
dc.identifier.uri
https://repositorio.uchile.cl/handle/2250/160679
Abstract
dc.description.abstract
Several divalent cations were studied as agonists of a Ca2+-activated K+ channel obtained from rat muscle membranes and incorporated into planar lipid bilayers. The effect of these agonists on single-channel currents was tested in the absence and in the presence of Ca2+. Among the divalent cations that activate the channel, Ca2+ is the most effective, followed by Cd2+, Sr2+, Mn2+, Fe2+, and Co2+. Mg2+, Ni2+, Ba2+, Cu2+, Zn2+, Hg2+, and Sn2+ are ineffective. The voltage dependence of channel activation is the same for all the divalent cations. The time-averaged probability of the open state is a sigmoidal function of the divalent cation concentration. The sigmoidal curves are described by a dissociation constant K and a Hill coefficient N. The values of these parameters, measured at 80 mV are: N = 2.1, K- 4 × 10-7 mMN for Ca2+; N = 3.0, K = 0.02 mMN for Cd2+; N = 1.45, K = 0.63 mMN for Sr2+; N = 1.7, K = 0.94 mMN for Mn2+; N = 1.1, K = 3.0 mMN for Fe2+; and N = 1.1 K = 4.35 mMN for Co2+