Title
HCN2 channels : a permanent open state and conductance changes HCN2 channels : a permanent open state and conductance changes
Author
Faculty/Department
Faculty of Medicine and Health Sciences
Publication type
article
Publication
New York, N.Y. ,
Subject
Chemistry
Biology
Human medicine
Source (journal)
The journal of membrane biology. - New York, N.Y.
Volume/pages
248(2015) :1 , p. 67-81
ISSN
0022-2631
ISI
000348279300009
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
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.
E-info
https://repository.uantwerpen.be/docman/iruaauth/57c1ee/134424.pdf
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000348279300009&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000348279300009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000348279300009&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle