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Voltage‐gated K + currents in freshly isolated myocytes of the pregnant human myometrium
Author(s) -
Knock Gregory A.,
Smirnov Sergey V.,
Aaronson Philip I.
Publication year - 1999
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1999.0769p.x
Subject(s) - tetraethylammonium , myometrium , biophysics , myocyte , chemistry , membrane potential , 4 aminopyridine , kinetics , depolarization , patch clamp , voltage clamp , potassium channel , potassium , biology , endocrinology , uterus , biochemistry , receptor , physics , organic chemistry , quantum mechanics
1 Voltage‐gated K + currents in human myometrium are not well characterized, and were therefore investigated, using the whole‐cell patch clamp technique, in freshly isolated myometrial smooth muscle cells from pregnant women at term. 2 Three types of voltage‐gated K + currents were identified. I K1 was a 4‐aminopyridine‐insensitive current with a negative half‐inactivation ( V 0.5 = ‐61 to ‐67 mV) and negative activation characteristics (threshold between ‐60 and ‐40 mV) and slow kinetics. I K2 was a 4‐aminopyridine‐sensitive current (half‐maximal block at ≈1 mM) with relatively positive half‐inactivation (V 0.5 = ‐30 mV) and activation characteristics (threshold between ‐40 and ‐30 mV) and faster kinetics. I K,A was a 4‐aminopyridine‐sensitive current with a negative inactivation and very fast inactivation kinetics. 3 Both I K1 and I K2 were sensitive to high concentrations of tetraethylammonium (half‐maximal block at ≈3 mM) and low concentrations of clofilium (half‐maximal block by 3‐10 μM). 4 IK1 and I K2 were unevenly distributed between myometrial cells, most cells possessing either I K1 (30 cells) or I K2 (24 cells) as the predominant current. 5 The characteristics of these currents suggest a possible function in the control of membrane potentials and smooth muscle quiescence in the pregnant human myometrium.