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Inhibition of human ether-a-go-go-related gene potassium channels by alpha 1-adrenoceptor antagonists prazosin, doxazosin, and terazosin.
Naunyn Schmiedebergs Arch Pharmacol. 2004 May; 369(5):462-72.NS

Abstract

Human ether-a-go-go-related gene (HERG) potassium channels are expressed in multiple tissues including the heart and adenocarcinomas. In cardiomyocytes, HERG encodes the alpha-subunit underlying the rapid component of the delayed rectifier potassium current, I(Kr), and pharmacological reduction of HERG currents may cause acquired long QT syndrome. In addition, HERG currents have been shown to be involved in the regulation of cell proliferation and apoptosis. Selective alpha 1-adrenoceptor antagonists are commonly used in the treatment of hypertension and benign prostatic hyperplasia. Recently, doxazosin has been associated with an increased risk of heart failure. Moreover, quinazoline-derived alpha 1-inhibitors induce apoptosis in cardiomyocytes and prostate tumor cells independently of alpha1-adrenoceptor blockade. To assess the action of the effects of prazosin, doxazosin, and terazosin on HERG currents, we investigated their acute electrophysiological effects on cloned HERG potassium channels heterologously expressed in Xenopus oocytes and HEK 293 cells.Prazosin, doxazosin, and terazosin blocked HERG currents in Xenopus oocytes with IC(50) values of 10.1, 18.2, and 113.2 microM respectively, whereas the IC(50) values for HERG channel inhibition in human HEK 293 cells were 1.57 microM, 585.1 nM, and 17.7 microM. Detailed biophysical studies revealed that inhibition by the prototype alpha 1-blocker prazosin occurred in closed, open, and inactivated channels. Analysis of the voltage-dependence of block displayed a reduction of inhibition at positive membrane potentials. Frequency-dependence was not observed. Prazosin caused a negative shift in the voltage-dependence of both activation (-3.8 mV) and inactivation (-9.4 mV). The S6 mutations Y652A and F656A partially attenuated (Y652A) or abolished (F656A) HERG current blockade, indicating that prazosin binds to a common drug receptor within the pore-S6 region. In conclusion, this study demonstrates that HERG potassium channels are blocked by prazosin, doxazosin, and terazosin. These data may provide a hypothetical molecular explanation for the apoptotic effect of quinazoline-derived alpha1-adrenoceptor antagonists.

Authors+Show Affiliations

Department of Cardiology, Medical University Hospital Heidelberg, Bergheimerstrasse 58, 69115, Heidelberg, Germany. Dierk_Thomas@med.uni-heidelberg.deNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo 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

15098086

Citation

Thomas, Dierk, et al. "Inhibition of Human Ether-a-go-go-related Gene Potassium Channels By Alpha 1-adrenoceptor Antagonists Prazosin, Doxazosin, and Terazosin." Naunyn-Schmiedeberg's Archives of Pharmacology, vol. 369, no. 5, 2004, pp. 462-72.
Thomas D, Wimmer AB, Wu K, et al. Inhibition of human ether-a-go-go-related gene potassium channels by alpha 1-adrenoceptor antagonists prazosin, doxazosin, and terazosin. Naunyn Schmiedebergs Arch Pharmacol. 2004;369(5):462-72.
Thomas, D., Wimmer, A. B., Wu, K., Hammerling, B. C., Ficker, E. K., Kuryshev, Y. A., Kiehn, J., Katus, H. A., Schoels, W., & Karle, C. A. (2004). Inhibition of human ether-a-go-go-related gene potassium channels by alpha 1-adrenoceptor antagonists prazosin, doxazosin, and terazosin. Naunyn-Schmiedeberg's Archives of Pharmacology, 369(5), 462-72.
Thomas D, et al. Inhibition of Human Ether-a-go-go-related Gene Potassium Channels By Alpha 1-adrenoceptor Antagonists Prazosin, Doxazosin, and Terazosin. Naunyn Schmiedebergs Arch Pharmacol. 2004;369(5):462-72. PubMed PMID: 15098086.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Inhibition of human ether-a-go-go-related gene potassium channels by alpha 1-adrenoceptor antagonists prazosin, doxazosin, and terazosin. AU - Thomas,Dierk, AU - Wimmer,Anna-Britt, AU - Wu,Kezhong, AU - Hammerling,Bettina C, AU - Ficker,Eckhard K, AU - Kuryshev,Yuri A, AU - Kiehn,Johann, AU - Katus,Hugo A, AU - Schoels,Wolfgang, AU - Karle,Christoph A, Y1 - 2004/04/20/ PY - 2003/12/11/received PY - 2004/03/27/accepted PY - 2004/4/21/pubmed PY - 2004/12/16/medline PY - 2004/4/21/entrez SP - 462 EP - 72 JF - Naunyn-Schmiedeberg's archives of pharmacology JO - Naunyn Schmiedebergs Arch. Pharmacol. VL - 369 IS - 5 N2 - Human ether-a-go-go-related gene (HERG) potassium channels are expressed in multiple tissues including the heart and adenocarcinomas. In cardiomyocytes, HERG encodes the alpha-subunit underlying the rapid component of the delayed rectifier potassium current, I(Kr), and pharmacological reduction of HERG currents may cause acquired long QT syndrome. In addition, HERG currents have been shown to be involved in the regulation of cell proliferation and apoptosis. Selective alpha 1-adrenoceptor antagonists are commonly used in the treatment of hypertension and benign prostatic hyperplasia. Recently, doxazosin has been associated with an increased risk of heart failure. Moreover, quinazoline-derived alpha 1-inhibitors induce apoptosis in cardiomyocytes and prostate tumor cells independently of alpha1-adrenoceptor blockade. To assess the action of the effects of prazosin, doxazosin, and terazosin on HERG currents, we investigated their acute electrophysiological effects on cloned HERG potassium channels heterologously expressed in Xenopus oocytes and HEK 293 cells.Prazosin, doxazosin, and terazosin blocked HERG currents in Xenopus oocytes with IC(50) values of 10.1, 18.2, and 113.2 microM respectively, whereas the IC(50) values for HERG channel inhibition in human HEK 293 cells were 1.57 microM, 585.1 nM, and 17.7 microM. Detailed biophysical studies revealed that inhibition by the prototype alpha 1-blocker prazosin occurred in closed, open, and inactivated channels. Analysis of the voltage-dependence of block displayed a reduction of inhibition at positive membrane potentials. Frequency-dependence was not observed. Prazosin caused a negative shift in the voltage-dependence of both activation (-3.8 mV) and inactivation (-9.4 mV). The S6 mutations Y652A and F656A partially attenuated (Y652A) or abolished (F656A) HERG current blockade, indicating that prazosin binds to a common drug receptor within the pore-S6 region. In conclusion, this study demonstrates that HERG potassium channels are blocked by prazosin, doxazosin, and terazosin. These data may provide a hypothetical molecular explanation for the apoptotic effect of quinazoline-derived alpha1-adrenoceptor antagonists. SN - 0028-1298 UR - https://www.unboundmedicine.com/medline/citation/15098086/Inhibition_of_human_ether_a_go_go_related_gene_potassium_channels_by_alpha_1_adrenoceptor_antagonists_prazosin_doxazosin_and_terazosin_ L2 - https://dx.doi.org/10.1007/s00210-004-0931-8 DB - PRIME DP - Unbound Medicine ER -