Publication
Title
HCN2 channels : a permanent open state and conductance changes
Author
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in the membranes of heart and brain cells can conduct Na+ and K+ ions and activate between -30 and -120 mV. We express the alpha subunit of HCN2 channels in Xenopus laevis oocytes and are confronted with two unexpected problems. First, we observe a rise in membrane conductance at resting potential proportional to the amount of expression. On activation to hyperpolarizing potentials, the instantaneous conductance rises in proportion to the amount of activated current. CsCl reduces the observed effects. This can be explained by the expression in oocytes membranes of a fraction of permanently open HCN2 channels. Second, using TEVC technique, our data show a completely different behaviour in physiological solutions of heterogeneously expressed HCN2 currents from what is observed in wild-type currents in the absence of drugs. During pulse trains, we frequently observe (1) a fast and significant decline of the amplitude of HCN2 current during hyperpolarizing steps, (2) no recovery of this decline after a long period at resting membrane potential, (3) a different behaviour of the tail currents at depolarization with other and slower changes than during activation, (4) recovery of this decline in high K+/low Na+ bath solution. The decline of the HCN2 current in physiological conditions is caused by a reduction of the conductance of the HCN2 channel presumably caused by the mere presence of sodium in the channel, in competition with potassium ions and with a limitative effect on the channel conductance.
Language
English
Source (journal)
The journal of membrane biology. - New York, N.Y.
Publication
New York, N.Y. : 2015
ISSN
0022-2631
Volume/pages
248:1(2015), p. 67-81
ISI
000348279300009
Full text (Publishers DOI)
Full text (publishers version - intranet only)
UAntwerpen
Faculty/Department
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 20.07.2016
Last edited 24.04.2017
To cite this reference