NDLI: Voltage-dependent blockade of HERG channels expressed in Xenopus oocytes by external Ca2+ and Mg2+

Content Provider	PubMed Central
Author	Ho, Won-kyung Kim, Injune Lee, Chin O. Earm, Yung E.
Copyright Year	1998
Abstract	We expressed the human eag-related gene (HERG), which is known to encode the delayed rectifier K+ current (I Kr) in cardiac muscle, in Xenopus oocytes. Using a two-microelectrode voltage clamp technique, the effect of external Ca2+ and Mg2+ on the HERG current (I HERG) was investigated. When [Ca2+]o was increased, the amplitude of outward I HERG elicited by depolarization decreased, and the rate of current onset slowed. The rate of current decay observed on repolarization was greatly accelerated. The threshold and fully activated potential of I HERG shifted to a more positive potential. On the other hand, the inactivation property represented by the negative slope of the I-V curve and the instantaneous conductance of I HERG were little affected by [Ca2+]o. The effect of [Ca2+]o on I HERG can be interpreted using the channel blockade model. The blockade is voltage dependent; smaller dissociation constants (K M) at more negative potentials indicate that block is facilitated by hyperpolarization. K M changes e-fold for 14.5 mV and the fractional electrical distance of the binding site calculated from this value is 0.86. Blockade by a low concentration of Ca2+ (0.5 mm) was inhibited by increasing [K+]o (from 2 to 20 mm), whereas blockade by a high concentration of Ca2+ (5 mm) was not affected by varying [K+]o, indicating that there is competition between permeating ions and blocking ions. The effect of [Mg2+]o on I HERG was qualitatively similar to that of [Ca2+]o, but the potency was lower. These results suggest that external Ca2+ and Mg2+ block the HERG channel in a voltage- and time-dependent manner, resulting in a voltage dependence which has been regarded as a property of the activation gate.
Related Links	http://dx.doi.org/10.1111/j.1469-7793.1998.631bs.x
Ending Page	638
Page Count	8
Starting Page	631
File Format	PDF
ISSN	00223751
e-ISSN	14697793
Journal	The Journal of Physiology
Issue Number	Pt 3
Volume Number	507
Language	English
Publisher	Blackwell Science Inc
Publisher Date	1998-03-01
Access Restriction	Open
Rights Holder	Blackwell Science Inc
Subject Keyword	Physiology Research in Higher Education
Content Type	Text
Resource Type	Article
Subject	Physiology Sports Science

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Blockade of HERG channels expressed in Xenopus laevis oocytes by external divalent cations.

Voltage-dependent blockade of HERG channels expressed inXenopusoocytes by external $Ca^{2+}$and $Mg^{2+}$

Blockade of HERG channels expressed in Xenopus oocytes by external H+

A mutation in the pore region of HERG K+ channels expressed in Xenopus oocytes reduces rectification by shifting the voltage dependence of inactivation

State-dependent barium block of wild-type and inactivation-deficient HERG channels in Xenopus oocytes

Internal Mg2+ block of recombinant NMDA channels mutated within the selectivity filter and expressed in Xenopus oocytes

Characterization of voltage-dependent calcium channels expressed in Xenopus oocytes injected with mRNA from rat heart.

Mutations of the S4-S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes

Internal Na+ and Mg2+ blockade of DRK1 (Kv2.1) potassium channels expressed in Xenopus oocytes. Inward rectification of a delayed rectifier

Voltage-dependent blockade of HERG channels expressed in Xenopus oocytes by external Ca2+ and Mg2+

Similar Documents

Blockade of HERG channels expressed in Xenopus laevis oocytes by external divalent cations.

Voltage-dependent blockade of HERG channels expressed inXenopusoocytes by external $Ca^{2+}$and $Mg^{2+}$

Blockade of HERG channels expressed in Xenopus oocytes by external H+

A mutation in the pore region of HERG K+ channels expressed in Xenopus oocytes reduces rectification by shifting the voltage dependence of inactivation

State-dependent barium block of wild-type and inactivation-deficient HERG channels in Xenopus oocytes

Internal Mg2+ block of recombinant NMDA channels mutated within the selectivity filter and expressed in Xenopus oocytes

Characterization of voltage-dependent calcium channels expressed in Xenopus oocytes injected with mRNA from rat heart.

Mutations of the S4-S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes

Internal Na+ and Mg2+ blockade of DRK1 (Kv2.1) potassium channels expressed in Xenopus oocytes. Inward rectification of a delayed rectifier

Voltage-dependent blockade of HERG channels expressed in Xenopus oocytes by external Ca2+ and Mg2+