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Demonstration of calcium-activated transient outward chloride current and delayed rectifier potassium currents in Swine atrial myocytes.
J Mol Cell Cardiol. 2004 Apr; 36(4):495-504.JM

Abstract

Cellular electrophysiology is not fully understood in the atrium of pig heart. The objective of the present study was to determine whether transient outward current (I(to)), ultra-rapid delayed rectifier potassium current (I(Kur)), and rapid and slow delayed rectifier K(+) currents (I(Kr) and I(Ks)) were present in pig atrium. The whole-cell patch technique was applied to record membrane currents and action potentials in myocytes isolated from pig atrium. It was found that an I(to) was activated upon depolarization voltage steps to between -10 and +60 mV from -50 mV in pig atrial cells, and the I(to) was sensitive to the inhibition by the blockade of L-type calcium (Ca(2+)) current, showed a "bell-shaped" I-V relationship, typical of I(to2) (i.e. I(Cl.Ca)). The I(to2) was inhibited by the chloride (Cl(-)) channel blocker anthracene-9-carboxylic acid (9-AC, 200 micromol/l) or 4,4'-diisothiocyanostilben-2,2'disulfonic acid (200 micromol/l), and by Cl(-) substitution in the superfusate. I(Kur) was found in pig atrial myocytes, and the current showed properties of weak inward rectification and use- and frequency-dependent reduction. I(Kur) was resistant to tetraethylammonium, but sensitive to inhibition by 4-aminopyridine (4-AP) (IC(50) = 71.7 +/- 3.5 micromol/l). In addition, E-4031-sensitive I(Kr) and chromanol 293B-sensitive I(Ks) were observed in pig atrial myocytes. Blockade of I(to2), I(Kur), I(Kr) or I(Ks) with corresponding blockers significantly prolonged atrial action potentials. These results indicate that Ca(2+)-activated I(to2), 4-AP-sensitive I(Kur), E-4031-sensitive I(Kr), and 293B-sensitive I(Ks) are present in pig atrial myocytes, and these currents play important roles in action potential repolarization of pig atria.

Authors+Show Affiliations

Department of Medicine Institute of Cardiovascular Science and Medicine, L8-01, Laboratory Block, Faculty of Medicine Building, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong, SAR, China. grli@hkucc.hku.hkNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15081309

Citation

Li, Gui-Rong, et al. "Demonstration of Calcium-activated Transient Outward Chloride Current and Delayed Rectifier Potassium Currents in Swine Atrial Myocytes." Journal of Molecular and Cellular Cardiology, vol. 36, no. 4, 2004, pp. 495-504.
Li GR, Sun H, To J, et al. Demonstration of calcium-activated transient outward chloride current and delayed rectifier potassium currents in Swine atrial myocytes. J Mol Cell Cardiol. 2004;36(4):495-504.
Li, G. R., Sun, H., To, J., Tse, H. F., & Lau, C. P. (2004). Demonstration of calcium-activated transient outward chloride current and delayed rectifier potassium currents in Swine atrial myocytes. Journal of Molecular and Cellular Cardiology, 36(4), 495-504.
Li GR, et al. Demonstration of Calcium-activated Transient Outward Chloride Current and Delayed Rectifier Potassium Currents in Swine Atrial Myocytes. J Mol Cell Cardiol. 2004;36(4):495-504. PubMed PMID: 15081309.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Demonstration of calcium-activated transient outward chloride current and delayed rectifier potassium currents in Swine atrial myocytes. AU - Li,Gui-Rong, AU - Sun,Haiying, AU - To,Jensen, AU - Tse,Hung-Fat, AU - Lau,Chu-Pak, PY - 2003/08/09/received PY - 2003/12/29/revised PY - 2004/01/06/accepted PY - 2004/4/15/pubmed PY - 2004/12/16/medline PY - 2004/4/15/entrez SP - 495 EP - 504 JF - Journal of molecular and cellular cardiology JO - J Mol Cell Cardiol VL - 36 IS - 4 N2 - Cellular electrophysiology is not fully understood in the atrium of pig heart. The objective of the present study was to determine whether transient outward current (I(to)), ultra-rapid delayed rectifier potassium current (I(Kur)), and rapid and slow delayed rectifier K(+) currents (I(Kr) and I(Ks)) were present in pig atrium. The whole-cell patch technique was applied to record membrane currents and action potentials in myocytes isolated from pig atrium. It was found that an I(to) was activated upon depolarization voltage steps to between -10 and +60 mV from -50 mV in pig atrial cells, and the I(to) was sensitive to the inhibition by the blockade of L-type calcium (Ca(2+)) current, showed a "bell-shaped" I-V relationship, typical of I(to2) (i.e. I(Cl.Ca)). The I(to2) was inhibited by the chloride (Cl(-)) channel blocker anthracene-9-carboxylic acid (9-AC, 200 micromol/l) or 4,4'-diisothiocyanostilben-2,2'disulfonic acid (200 micromol/l), and by Cl(-) substitution in the superfusate. I(Kur) was found in pig atrial myocytes, and the current showed properties of weak inward rectification and use- and frequency-dependent reduction. I(Kur) was resistant to tetraethylammonium, but sensitive to inhibition by 4-aminopyridine (4-AP) (IC(50) = 71.7 +/- 3.5 micromol/l). In addition, E-4031-sensitive I(Kr) and chromanol 293B-sensitive I(Ks) were observed in pig atrial myocytes. Blockade of I(to2), I(Kur), I(Kr) or I(Ks) with corresponding blockers significantly prolonged atrial action potentials. These results indicate that Ca(2+)-activated I(to2), 4-AP-sensitive I(Kur), E-4031-sensitive I(Kr), and 293B-sensitive I(Ks) are present in pig atrial myocytes, and these currents play important roles in action potential repolarization of pig atria. SN - 0022-2828 UR - https://www.unboundmedicine.com/medline/citation/15081309/Demonstration_of_calcium_activated_transient_outward_chloride_current_and_delayed_rectifier_potassium_currents_in_Swine_atrial_myocytes_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022282804000082 DB - PRIME DP - Unbound Medicine ER -