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Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin.
Sheng Li Xue Bao. 2008 Aug 25; 60(4):525-34.SL

Abstract

In the present study, we investigated the inhibitory action of ketanserin on wild-type (WT) and Y652 mutant human ether-a-go-go-related gene (HERG) potassium channels expressed in Xenopus oocytes and the effects of changing the channel molecular determinants characteristics on the blockade with and without ketanserin intervention using standard two-microelectrode voltage-clamp techniques. Point mutations were introduced into HERG gene (Y652A and Y652R) and subcloned into the pSP64 plasmid expression vector. Complementary RNAs for injection into oocytes were prepared with SP6 Cap-Scribe after linearization of the expression construct with EcoR I. Clampfit 9.2 software was employed for data collection and analysis. Origin 6.0 software was used to fit the data, calculate time constants and plot histograms. The results showed that ketanserin blocked WT HERG currents in voltage- and concentration-dependent manner and showed minimal tonic blockade of HERG current evaluated by the envelope of tails test. The IC50 value was (0.38+/-0.04) micromol/L for WT HERG potassium channel. The peaks of the I-V relationship for HERG channel suggested a negative shift in the voltage-dependence of activation after using ketanserin, whose midpoint of activation values (V1/2) were (-16.59+/-1.01) mV (control) vs (-20.59+/-0.87) mV (ketanserin) at 0.1 micromol/L, (-22.39+/-0.94) mV at 1 micromol/L, (-23.51+/-0.91) mV at 10 micromol/L, respectively (P<0.05, n=6). Characteristics of blockade were consistent with an open-state channel blockade, because the extent and rate of onset of blockade was voltage-dependent, increasing at more potentials even in the condition of leftward shift of activation curve. Meanwhile, in the different depolarization duration, the fractional blockade of end-pulse step current and peak tail current at 100 ms duration was significantly lower than that at 400 ms and 700 ms, which indicated that following the channel activation fractional blockade was enhanced by the activated channels. Ketanserin could also modulate the inactivation of HERG channel, which shifted the voltage-dependence of WT HERG channel inactivation curve from (-51.71+/-2.15) mV to (-80.76+/-14.98) mV (P<0.05, n=4). The S6 mutation, Y652A and Y652R, significantly attenuated the blockade by ketanserin. The IC50 value were (27.13+/-9.40) micromol/L and (20.20+/-2.80) micromol/L, respectively, increased by approximately 72-fold for Y652A and 53-fold for Y652R compared to that of WT HERG channel blockade [(0.38+/-0.04) micromol/L]. However, between the inhibitory effects of Y652A and Y652R, there was no significant difference. In conclusion, ketanserin blocks WT HERG currents in voltage- and concentration-dependent manner and preferentially blocks open-state HERG channels. Tyr-652 is one of the critical residues in the ketanserin-binding sites.

Authors+Show Affiliations

Research Center of Ion Channelopathy, Department of Cardiology, Institute of Cardiovascular Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

18690396

Citation

Tu, Dan-Na, et al. "Blockade of the Human Ether-a-go-go-related Gene Potassium Channel By Ketanserin." Sheng Li Xue Bao : [Acta Physiologica Sinica], vol. 60, no. 4, 2008, pp. 525-34.
Tu DN, Zou AR, Liao YH, et al. Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin. Sheng Li Xue Bao. 2008;60(4):525-34.
Tu, D. N., Zou, A. R., Liao, Y. H., Du, Y. M., Wang, X. P., & Li, L. (2008). Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin. Sheng Li Xue Bao : [Acta Physiologica Sinica], 60(4), 525-34.
Tu DN, et al. Blockade of the Human Ether-a-go-go-related Gene Potassium Channel By Ketanserin. Sheng Li Xue Bao. 2008 Aug 25;60(4):525-34. PubMed PMID: 18690396.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin. AU - Tu,Dan-Na, AU - Zou,An-Ruo, AU - Liao,Yu-Hua, AU - Du,Yi-Mei, AU - Wang,Xian-Pei, AU - Li,Lu, PY - 2008/8/12/pubmed PY - 2015/5/20/medline PY - 2008/8/12/entrez SP - 525 EP - 34 JF - Sheng li xue bao : [Acta physiologica Sinica] JO - Sheng Li Xue Bao VL - 60 IS - 4 N2 - In the present study, we investigated the inhibitory action of ketanserin on wild-type (WT) and Y652 mutant human ether-a-go-go-related gene (HERG) potassium channels expressed in Xenopus oocytes and the effects of changing the channel molecular determinants characteristics on the blockade with and without ketanserin intervention using standard two-microelectrode voltage-clamp techniques. Point mutations were introduced into HERG gene (Y652A and Y652R) and subcloned into the pSP64 plasmid expression vector. Complementary RNAs for injection into oocytes were prepared with SP6 Cap-Scribe after linearization of the expression construct with EcoR I. Clampfit 9.2 software was employed for data collection and analysis. Origin 6.0 software was used to fit the data, calculate time constants and plot histograms. The results showed that ketanserin blocked WT HERG currents in voltage- and concentration-dependent manner and showed minimal tonic blockade of HERG current evaluated by the envelope of tails test. The IC50 value was (0.38+/-0.04) micromol/L for WT HERG potassium channel. The peaks of the I-V relationship for HERG channel suggested a negative shift in the voltage-dependence of activation after using ketanserin, whose midpoint of activation values (V1/2) were (-16.59+/-1.01) mV (control) vs (-20.59+/-0.87) mV (ketanserin) at 0.1 micromol/L, (-22.39+/-0.94) mV at 1 micromol/L, (-23.51+/-0.91) mV at 10 micromol/L, respectively (P<0.05, n=6). Characteristics of blockade were consistent with an open-state channel blockade, because the extent and rate of onset of blockade was voltage-dependent, increasing at more potentials even in the condition of leftward shift of activation curve. Meanwhile, in the different depolarization duration, the fractional blockade of end-pulse step current and peak tail current at 100 ms duration was significantly lower than that at 400 ms and 700 ms, which indicated that following the channel activation fractional blockade was enhanced by the activated channels. Ketanserin could also modulate the inactivation of HERG channel, which shifted the voltage-dependence of WT HERG channel inactivation curve from (-51.71+/-2.15) mV to (-80.76+/-14.98) mV (P<0.05, n=4). The S6 mutation, Y652A and Y652R, significantly attenuated the blockade by ketanserin. The IC50 value were (27.13+/-9.40) micromol/L and (20.20+/-2.80) micromol/L, respectively, increased by approximately 72-fold for Y652A and 53-fold for Y652R compared to that of WT HERG channel blockade [(0.38+/-0.04) micromol/L]. However, between the inhibitory effects of Y652A and Y652R, there was no significant difference. In conclusion, ketanserin blocks WT HERG currents in voltage- and concentration-dependent manner and preferentially blocks open-state HERG channels. Tyr-652 is one of the critical residues in the ketanserin-binding sites. SN - 0371-0874 UR - https://www.unboundmedicine.com/medline/citation/18690396/Blockade_of_the_human_ether_a_go_go_related_gene_potassium_channel_by_ketanserin_ L2 - http://www.actaps.com.cn/qikan/manage/wenzhang/2008-4-12.pdf DB - PRIME DP - Unbound Medicine ER -