| 11123705 |
Frey BW, Lynch FT, Kinsella JM, Horowitz B, Sanders KM, Carl A: Blocking of cloned and native delayed rectifier K channels from visceral smooth muscles by phencyclidine. Neurogastroenterol Motil. 2000 Dec;12(6):509-16.
We investigated the effect of phencyclidine (PCP) on three native delayed rectifier K+ currents and three channels cloned from canine and human circular colonic myocytes using voltage-clamp techniques. Native delayed rectifier K+ current in canine circular colon is composed of at least three components: (i) a rapidly activating, 4-aminopyridine-sensitive component (termed IdK (f)); (ii) a slowly activating, tetraethylammonium (TEA)-sensitive component (IdK (s)); and (iii) a rapidly activating, TEA-sensitive component, which has a steady-state inactivation curve shifted towards more negative potentials (IdK (n)). PCP blocked all three components with EC50 values of 45, 27 and 59 micromol L-1, respectively. Blocking was neither use-dependent nor voltage-dependent. Delayed rectifier K+ channels cloned from canine (Kv1.2, Kv1.5) and from human (Kv2.2) colon were expressed in Xenopus oocytes. PCP blocked all three currents with similar potency. In contrast, PCP (up to 10-4 mol L-1) did not reduce the magnitude of Ca2+-dependent outward current of large conductance Ca2+-activated K+ channels (BK channels). |
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