In single myocytes of the guinea pig taenia coli, dispersed by enzymatic digestion, the late outward current is carried by K+. It has both a Ca2+-activated component and a voltage-dependent component which is resistant to external Co2+. The reversal potential is -84 mV, and the channel(s) for it are highly selective to K+. At 33 degrees C, the activation follows n2 kinetics, with a voltage-dependent time constant of 10.6 ms at 0 mV, which shortens to 1.7 ms at +70 mV. Deactivation follows a single-exponential time course, with a voltage-dependent time constant of 11 ms at -50 mV, which lengthens to 33 ms at -20 mV. During a 4.5-s maintained depolarization, IK inactivates, most of it into two exponential components, but there is a small noninactivating residue. It is surmised that during an action potential under physiological conditions, there is sufficient IK to cause repolarization.
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1 March 1989
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March 01 1989
Outward current in single smooth muscle cells of the guinea pig taenia coli.
Y Yamamoto,
Y Yamamoto
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
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S L Hu,
S L Hu
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
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C Y Kao
C Y Kao
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
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Y Yamamoto
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
S L Hu
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
C Y Kao
Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1989) 93 (3): 551–564.
Citation
Y Yamamoto, S L Hu, C Y Kao; Outward current in single smooth muscle cells of the guinea pig taenia coli.. J Gen Physiol 1 March 1989; 93 (3): 551–564. doi: https://doi.org/10.1085/jgp.93.3.551
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