Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc.

Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Research Abstract Details 

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Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Abstract Text:

Dao-Qi Zhang,Ziyi Sun,Douglas G McMahon,

Extracellular Ca2+ and Zn2+ influence many aspects of retinal function. Here, we examined the effect of external Ca2+ and Zn2+ on potassium channels of retinal horizontal cells. When extracellular Ca2+ was lowered from 3 mM to 0.3 mM, horizontal cell transient outward currents elicited by voltage steps from resting membrane potential (-70 mV) were decreased by approximately 50%, whereas the sustained currents remained unchanged. This effect was due to a hyperpolarizing shift in the steady-state inactivation curve of A-type K+ currents when extracellular Ca2+ concentration was lowered. The mean half inactivation potential of the steady-state inactivation curves was hyperpolarized from -56.3 +/- 4.7 mV in 3 mM Ca2+ to -76.4 +/- 3.9 mV in 0.3 mM Ca2+. Neither the state-steady activation curve nor the kinetics of inactivation was significantly changed in low extracellular Ca2+. The addition of 30 microM Zn2+ restored peak outward currents in 0.3 mM Ca2+. The half inactivation voltages were depolarized from -70 +/- 2.8 mV in 0.3 mM Ca2+ to -56 +/- 2.6 mV in 0.3 mM Ca2+ plus 30 microM Zn2+. Taken together, the results indicate that external Ca2+ and Zn2+ maintain the activity of A-type potassium channels in retinal horizontal cells by influencing the voltage dependence of steady-state inactivation.

Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Publishing Authors By Initials

DQ Zhang,Z Sun,DG McMahon,

For similar inorganic chemicals: elements: metals, heavy: zinc research abstracts see: inorganic chemicals: elements: metals, heavy: zinc research

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Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: Visual neuroscience

VOLUME: 23

Page Numbers: 825-32

Journal Abbreviation: Vis. Neurosci.

ISSN: 0952-5238

DAY: 3

MONTH: 12

YEAR: 2007

Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 8809466

Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Keywords Mesh Terms:

KEYWORDS: Zinc

MESH TERMS: pharmacology

Chemical & Substance for Abstract: Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc. Information

Substance Name: Calcium

Registry Number: 7440-70-2

Grant and Affiliation Information for Modulation of A-type potassium currents in retinal horizontal cells by extracellular calcium and zinc.

AFFILIATION: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235-1634, USA.

Country: England

AGENCY: United States NEI

GRANT: EY09256

ACRONYM: EY

MEDLINETA: Vis Neurosci

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