Ultraviolet Photoalteration of Late Na+ Current in Guinea-pig Ventricular Myocytes

Ultraviolet Photoalteration of Late Na+ Current in Guinea-pig Ventricular Myocytes UV irradiation has multiple effects on mammalian cells, including modification of ion channel function. The present study was undertaken to investigate the response of membrane currents in guinea-pig ventricular myocytes to the type A (355, 380 nm) irradiation commonly used in Ca2+ imaging studies. Myocytes configured for whole-cell voltage clamp were generally held at −80 mV, dialyzed with K+-, Na+-free pipette solution, and bathed with K+-free Tyrode’s solution at 22°C. During experiments that lasted for ≈ 35 min, UVA irradiation caused a progressive increase in slowly-inactivating inward current elicited by 200-ms depolarizations from −80 to −40 mV, but had little effect on background current or on L-type Ca2+ current. Trials with depolarized holding potential, Ca2+ channel blockers, and tetrodotoxin (TTX) established that the current induced by irradiation was late (slowly-inactivating) Na+ current (I Na). The amplitude of the late inward current sensitive to 100 μM TTX was increased by 3.5-fold after 20–30 min of irradiation. UVA modulation of late I Na may (i) interfere with imaging studies, and (ii) provide a paradigm for investigation of intracellular factors likely to influence slow inactivation of cardiac I Na. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Ultraviolet Photoalteration of Late Na+ Current in Guinea-pig Ventricular Myocytes

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Publisher
Springer-Verlag
Copyright
Copyright © 2006 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-005-0844-6
Publisher site
See Article on Publisher Site

Abstract

UV irradiation has multiple effects on mammalian cells, including modification of ion channel function. The present study was undertaken to investigate the response of membrane currents in guinea-pig ventricular myocytes to the type A (355, 380 nm) irradiation commonly used in Ca2+ imaging studies. Myocytes configured for whole-cell voltage clamp were generally held at −80 mV, dialyzed with K+-, Na+-free pipette solution, and bathed with K+-free Tyrode’s solution at 22°C. During experiments that lasted for ≈ 35 min, UVA irradiation caused a progressive increase in slowly-inactivating inward current elicited by 200-ms depolarizations from −80 to −40 mV, but had little effect on background current or on L-type Ca2+ current. Trials with depolarized holding potential, Ca2+ channel blockers, and tetrodotoxin (TTX) established that the current induced by irradiation was late (slowly-inactivating) Na+ current (I Na). The amplitude of the late inward current sensitive to 100 μM TTX was increased by 3.5-fold after 20–30 min of irradiation. UVA modulation of late I Na may (i) interfere with imaging studies, and (ii) provide a paradigm for investigation of intracellular factors likely to influence slow inactivation of cardiac I Na.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jun 17, 2006

References

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