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|Title:||Voltage-gated potassium currents in rat vas deferens smooth muscle cells|
|Authors:||Harhun, M. I.|
Jurkiewicz, N. H.
Kryshtal, D. O.
Shuba, M. F.
Vladimirova, I. A.
Bogomoletz Inst Physiol
Universidade Federal de São Paulo (UNIFESP)
A-type potassium current
delayed rectifying potassium current
|Citation:||Pflugers Archiv-european Journal of Physiology. New York: Springer-verlag, v. 446, n. 3, p. 380-386, 2003.|
|Abstract:||Voltage-gated components of the outward current in single smooth muscle cells isolated from the epididymal part of the rat vas deferens were studied using amphotericin B perforated patch-clamp techniques. the complex kinetics of the net outward current elicited by positive voltage steps from -80 mV to +40 mV suggested the presence of several components. Bath application of 200 nM charybdotoxin, a potent blocker of large-conductance, Ca2+-dependent K+ channels (BKCa), reduced the current amplitude significantly. When BKCa channels were suppressed, fast-inactivating (I-K,I-f) and delayed rectifying (I-K,I-dr) components of the outward current were identified. I-K,I-f was characterized by fast kinetics of current decay, negative steady-state activation and inactivation dependencies and sensitivity to 4-aminopyridine with an apparent K-d of 0.32 mM, properties similar to those of the A-type K+ current. in contrast, I-K,I-dr activated and inactivated at more positive potentials. the time constant of activation of I-K,I-dr was voltage dependent with an e-fold decrease per 21 mV depolarization. I-K,I-dr was inhibited by clofilium, a blocker of voltage-gated K+ channels, with an IC50 of 12 muM and was not blocked by 5 mM 4-aminopyridine. the possible significance of the voltage-gated currents is discussed.|
|Appears in Collections:||Em verificação - Geral|
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