Gating-dependent mechanism of 4-aminopyridine block in two related potassium channels - PubMed (original) (raw)
Gating-dependent mechanism of 4-aminopyridine block in two related potassium channels
G E Kirsch et al. J Gen Physiol. 1993 Nov.
Abstract
4-aminopyridine (4AP) is widely used as a selective blocker of voltage-activated K+ currents in excitable membranes, but its mechanism and site of action at the molecular level are not well understood. To address this problem we have analyzed 4AP block in Kv2.1 and Kv3.1, mammalian representatives of the Drosophila Shab and Shaw subfamilies of voltage-gated K+ channels, respectively. The two channels were expressed in Xenopus oocytes and analyzed at both the macroscopic and single channel levels. Whole cell analysis showed that 4AP sensitivity of Kv3.1 was approximately 150 times greater than that of Kv2.1. Patch clamp analysis revealed that the mechanism of 4AP block in both channels was qualitatively similar. 4AP reached its blocking site via the cytoplasmic side of the channels, the ON rate for block was strongly accelerated when channels opened and the drug was trapped in closed channels. Single channel analysis showed that 4AP decreased burst duration and increased the latency-to-first-opening. These effects were found to be related, respectively to drug ON and OFF rates in the activated channel. Kv3.1's high 4AP sensitivity relative to Kv2.1 was associated with both a slower OFF rate and therefore increased stability of the blocked state, as well as a faster ON rate and therefore increased access to the binding site. Our results indicate that in both channels 4AP enters the intracellular mouth to bind to a site that is guarded by the gating mechanism. Differences in channel gating as well as differences in the structure of the intracellular mouth may be important for specifying the 4AP sensitivity in related voltage-gated K+ channels.
Similar articles
- Reverse use dependence of Kv4.2 blockade by 4-aminopyridine.
Tseng GN, Jiang M, Yao JA. Tseng GN, et al. J Pharmacol Exp Ther. 1996 Nov;279(2):865-76. J Pharmacol Exp Ther. 1996. PMID: 8930194 - Segmental exchanges define 4-aminopyridine binding and the inner mouth of K+ pores.
Kirsch GE, Shieh CC, Drewe JA, Vener DF, Brown AM. Kirsch GE, et al. Neuron. 1993 Sep;11(3):503-12. doi: 10.1016/0896-6273(93)90154-j. Neuron. 1993. PMID: 8398143 - A Model of the Block of Voltage-Gated Potassium Kv4.2 Ionic Currents by 4-Aminopyridine.
Kehl SJ. Kehl SJ. J Pharmacol Exp Ther. 2017 Nov;363(2):184-195. doi: 10.1124/jpet.117.243097. Epub 2017 Sep 1. J Pharmacol Exp Ther. 2017. PMID: 28864468 - An essential 'set' of K+ channels conserved in flies, mice and humans.
Salkoff L, Baker K, Butler A, Covarrubias M, Pak MD, Wei A. Salkoff L, et al. Trends Neurosci. 1992 May;15(5):161-6. doi: 10.1016/0166-2236(92)90165-5. Trends Neurosci. 1992. PMID: 1377421 Review. - Molecular biology of the voltage-gated potassium channels of the cardiovascular system.
Roberds SL, Knoth KM, Po S, Blair TA, Bennett PB, Hartshorne RP, Snyders DJ, Tamkun MM. Roberds SL, et al. J Cardiovasc Electrophysiol. 1993 Feb;4(1):68-80. doi: 10.1111/j.1540-8167.1993.tb01214.x. J Cardiovasc Electrophysiol. 1993. PMID: 8287238 Review.
Cited by
- Kv2 channels contribute to neuronal activity within the vagal afferent-nTS reflex arc.
Ramirez-Navarro A, Lima-Silveira L, Glazebrook PA, Dantzler HA, Kline DD, Kunze DL. Ramirez-Navarro A, et al. Am J Physiol Cell Physiol. 2024 Jan 1;326(1):C74-C88. doi: 10.1152/ajpcell.00366.2023. Epub 2023 Nov 20. Am J Physiol Cell Physiol. 2024. PMID: 37982174 - Inactivation of the Kv2.1 channel through electromechanical coupling.
Fernández-Mariño AI, Tan XF, Bae C, Huffer K, Jiang J, Swartz KJ. Fernández-Mariño AI, et al. Nature. 2023 Oct;622(7982):410-417. doi: 10.1038/s41586-023-06582-8. Epub 2023 Sep 27. Nature. 2023. PMID: 37758949 Free PMC article. - Personalized structural biology reveals the molecular mechanisms underlying heterogeneous epileptic phenotypes caused by de novo KCNC2 variants.
Mukherjee S, Cassini TA, Hu N, Yang T, Li B, Shen W, Moth CW, Rinker DC, Sheehan JH, Cogan JD; Undiagnosed Diseases Network; Newman JH, Hamid R, Macdonald RL, Roden DM, Meiler J, Kuenze G, Phillips JA, Capra JA. Mukherjee S, et al. HGG Adv. 2022 Jul 19;3(4):100131. doi: 10.1016/j.xhgg.2022.100131. eCollection 2022 Oct 13. HGG Adv. 2022. PMID: 36035247 Free PMC article. - Mechanism of use-dependent Kv2 channel inhibition by RY785.
Marquis MJ, Sack JT. Marquis MJ, et al. J Gen Physiol. 2022 Jun 6;154(6):e202112981. doi: 10.1085/jgp.202112981. Epub 2022 Apr 18. J Gen Physiol. 2022. PMID: 35435946 Free PMC article. - Neuropeptide S Receptor Stimulation Excites Principal Neurons in Murine Basolateral Amygdala through a Calcium-Dependent Decrease in Membrane Potassium Conductance.
Park S, Flüthmann P, Wolany C, Goedecke L, Spenner HM, Budde T, Pape HC, Jüngling K. Park S, et al. Pharmaceuticals (Basel). 2021 May 27;14(6):519. doi: 10.3390/ph14060519. Pharmaceuticals (Basel). 2021. PMID: 34072275 Free PMC article.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Molecular Biology Databases
Miscellaneous