title: Direct block by bisindolylmaleimide of the voltage-dependent K+ currents of rat mesenteric arterial smooth muscle.
abstract: We investigated the effect of bisindolylmaleimide (I), a widely used protein kinase C (PKC) inhibitor, on the voltage-dependent K(+) (Kv) currents of rat mesenteric arterial smooth muscle cells using the whole-cell patch-clamp technique. Bisindolylmaleimide (I) reversibly and dose-dependently inhibited the Kv currents with an apparent K(d) value of 0.23+/-0.001 microM. The blockade was apparently through the acceleration of the decay rate of the Kv currents. The apparent rate constants of association and dissociation for bisindolylmaleimide (I) were 17.9+/-1.6 microM(-1) s(-1) and 4.1+/-1.5 s(-1), respectively. The inhibition of Kv current by bisindolylmaleimide (I) was steeply voltage-dependent between -30 and 0 mV (voltage range of channel activation). Bisindolylmaleimide (I) had no effect on the steady-state activation and inactivation of the Kv currents. Applications of trains of pulses at 1 or 2 Hz lead to a progressive increase in the bisindolylmaleimide (I)-blockade, and the recovery from bisindolylmaleimide (I)-block at -80 mV exhibited a time constant of 577.2+/-52.7 ms. Bisindolylmaleimide (V), an inactive analogue of bisindolylmaleimide (I), similarly inhibited the Kv currents with an apparent K(d) value of 1.48+/-0.004 microM, but other PKC inhibitor chelerythrine little affected the Kv currents. These results suggest that bisindolylmaleimide (I) directly inhibits the Kv currents of rat mesenteric arterial smooth muscle cells independently of PKC inhibition, in a state-, voltage-, time- and use-dependent manner.
authors.affiliation: Department of Physiology, College of Medicine, Konkuk University, 322 Danwol-dong, Choongju 380-701, South Korea.
authors.forename: Aeran
authors.initials: A
authors.lastname: Kim
authors.forename: Young Min
authors.initials: YM
authors.lastname: Bae
authors.forename: Junghwan
authors.initials: J
authors.lastname: Kim
authors.forename: Bokyung
authors.initials: B
authors.lastname: Kim
authors.forename: Won Kyung
authors.initials: WK
authors.lastname: Ho
authors.forename: Yung E
authors.initials: YE
authors.lastname: Earm
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Cho
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D008301:Maleimides / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007211:Indoles; D008301:Maleimides; D024642:Potassium Channels, Voltage-Gated; C088060:bisindolylmaleimide