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He L, Yu Z, Geng Z, Huang Z, Zhang C, Dong Y, Gao Y, Wang Y, Chen Q, Sun L, Ma X, Huang B, Wang X, Zhao Y. Structure, gating, and pharmacology of human Ca V3.3 channel. Nat Commun 2022; 13:2084. [PMID: 35440630 PMCID: PMC9019099 DOI: 10.1038/s41467-022-29728-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 03/28/2022] [Indexed: 12/19/2022] Open
Abstract
The low-voltage activated T-type calcium channels regulate cellular excitability and oscillatory behavior of resting membrane potential which trigger many physiological events and have been implicated with many diseases. Here, we determine structures of the human T-type CaV3.3 channel, in the absence and presence of antihypertensive drug mibefradil, antispasmodic drug otilonium bromide and antipsychotic drug pimozide. CaV3.3 contains a long bended S6 helix from domain III, with a positive charged region protruding into the cytosol, which is critical for T-type CaV channel activation at low voltage. The drug-bound structures clearly illustrate how these structurally different compounds bind to the same central cavity inside the CaV3.3 channel, but are mediated by significantly distinct interactions between drugs and their surrounding residues. Phospholipid molecules penetrate into the central cavity in various extent to shape the binding pocket and play important roles in stabilizing the inhibitor. These structures elucidate mechanisms of channel gating, drug recognition, and actions, thus pointing the way to developing potent and subtype-specific drug for therapeutic treatments of related disorders. T-type calcium channels are implicated in many diseases. Here, multiple structures of CaV3.3 channel elucidate molecular mechanisms of T-type CaV channels activation at low voltage and interaction with different clinically used channel blockers.
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Affiliation(s)
- Lingli He
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhuoya Yu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ze Geng
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Changjiang Zhang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuhang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qihao Chen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Le Sun
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, 100069, China
| | - Xinyue Ma
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China.,IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China
| | - Bo Huang
- StoneWise Ltd., 1708, Block B, No.19 Zhongguancun Street, Haidian District, Beijing, China
| | - Xiaoqun Wang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China. .,State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China. .,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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Ji D, Fleig A, Horgen FD, Feng ZP, Sun HS. Modulators of TRPM7 and its potential as a drug target for brain tumours. Cell Calcium 2021; 101:102521. [PMID: 34953296 DOI: 10.1016/j.ceca.2021.102521] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 12/14/2022]
Abstract
TRPM7 is a non-selective divalent cation channel with an alpha-kinase domain. Corresponding with its broad expression, TRPM7 has a role in a wide range of cell functions, including proliferation, migration, and survival. Growing evidence shows that TRPM7 is also aberrantly expressed in various cancers, including brain cancers. Because ion channels have widespread tissue distribution and result in extensive physiological consequences when dysfunctional, these proteins can be compelling drug targets. In fact, ion channels comprise the third-largest drug target type, following enzymes and receptors. Literature has shown that suppression of TRPM7 results in inhibition of migration, invasion, and proliferation in several human brain tumours. Therefore, TRPM7 presents a potential target for therapeutic brain tumour interventions. This article reviews current literature on TRPM7 as a potential drug target in the context of brain tumours and provides an overview of various selective and non-selective modulators of the channel relevant to pharmacology, oncology, and ion channel function.
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Affiliation(s)
- Delphine Ji
- Department of Surgery, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Department of Physiology, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Andrea Fleig
- Center for Biomedical Research at The Queen's Medical Center and John A. Burns School of Medicine and Cancer Center at the University of Hawaii, Honolulu, Hawaii 96813, USA
| | - F David Horgen
- Department of Natural Sciences, Hawaii Pacific University, Kaneohe, Hawaii 96744, USA
| | - Zhong-Ping Feng
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8.
| | - Hong-Shuo Sun
- Department of Surgery, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Department of Physiology, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Department of Pharmacology, Temerty Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8; Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario, Canada M5S 3M2.
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3
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Lee D, Hong JH. Ca 2+ Signaling as the Untact Mode during Signaling in Metastatic Breast Cancer. Cancers (Basel) 2021; 13:1473. [PMID: 33806911 PMCID: PMC8004807 DOI: 10.3390/cancers13061473] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 01/06/2023] Open
Abstract
Metastatic features of breast cancer in the brain are considered a common pathology in female patients with late-stage breast cancer. Ca2+ signaling and the overexpression pattern of Ca2+ channels have been regarded as oncogenic markers of breast cancer. In other words, breast tumor development can be mediated by inhibiting Ca2+ channels. Although the therapeutic potential of inhibiting Ca2+ channels against breast cancer has been demonstrated, the relationship between breast cancer metastasis and Ca2+ channels is not yet understood. Thus, we focused on the metastatic features of breast cancer and summarized the basic mechanisms of Ca2+-related proteins and channels during the stages of metastatic breast cancer by evaluating Ca2+ signaling. In particular, we highlighted the metastasis of breast tumors to the brain. Thus, modulating Ca2+ channels with Ca2+ channel inhibitors and combined applications will advance treatment strategies for breast cancer metastasis to the brain.
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Affiliation(s)
| | - Jeong Hee Hong
- Department of Health Sciences and Technology, Lee Gil Ya Cancer and Diabetes Institute, GAIHST, Gachon University, 155 Getbeolro, Yeonsu-gu, Incheon 21999, Korea;
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Njegic A, Wilson C, Cartwright EJ. Targeting Ca 2 + Handling Proteins for the Treatment of Heart Failure and Arrhythmias. Front Physiol 2020; 11:1068. [PMID: 33013458 PMCID: PMC7498719 DOI: 10.3389/fphys.2020.01068] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022] Open
Abstract
Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca2+) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca2+ is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca2+ cycling and signaling play a vital role in maintaining Ca2+ homeostasis. Changes to the expression levels and function of Ca2+-channels, pumps and associated intracellular handling proteins contribute to altered Ca2+ homeostasis in CVD. The remodeling of Ca2+-handling proteins therefore results in impaired Ca2+ cycling, Ca2+ leak from the sarcoplasmic reticulum and reduced Ca2+ clearance, all of which contributes to increased intracellular Ca2+. Currently, approved treatments for targeting Ca2+ handling dysfunction in CVD are focused on Ca2+ channel blockers. However, whilst Ca2+ channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca2+ homeostasis, this review will address the molecular changes to proteins associated with both Ca2+-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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Affiliation(s)
- Alexandra Njegic
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claire Wilson
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.,Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Elizabeth J Cartwright
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom
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Evaluation of ultra-early and dose-dependent edema and ultrastructural changes in the myocyte during anti-hypertensive drug delivery in the spontaneously hypertensive rat model. PLoS One 2020; 15:e0231244. [PMID: 32298274 PMCID: PMC7162487 DOI: 10.1371/journal.pone.0231244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 03/17/2020] [Indexed: 02/05/2023] Open
Abstract
Background Quantifying dose-dependent ultra-early edema and ultrastructural changes in the myocyte after drug delivery is important for the development of new mixed calcium channel blockers (CCBs). Materials and methods Arterial cannulation was used to measure mean arterial pressure in real time; simultaneously, magnetic resonance imaging proton density mapping was used to quantify edema 5–55 min after the delivery of L-type CCBs, T- and L-type CCBs, and solvent to a spontaneously hypertensive rat model. Transmission electron microscopy was used to show ultrastructural changes in the myocyte. Results Analysis of variance showed significant differences among the three groups in mean arterial pressure reduction (F = 246.36, P = 5.75E-25), ultra-early level of edema (ULE) (F = 175.49, P = 5.62E-22), and dose-dependent level of edema (DLE) (F = 199.48, P = 4.28E-23). Compared with the solvent’s mean arterial pressure reduction (2.65±6.56±1.64), ULE (1.16±0.09±0.02), and DLE (0.0010±0.0001±0.0000), post hoc tests showed that T- and L-type CCBs had better mean arterial pressure reduction (90.67±11.58±2.90, P = 1.06E-24 vs. 68.34±15.19±3.80, P = 1.76E-12), lower ULE (1.53±0.14±0.04, P = 4.74E-9 vs. 2.08±0.18±0.04, P = 2.68E-22), and lower DLE (0.0025±0.0004±0.0001, P = 1.14E-11 vs. 0.0047±0.0008±0.0002, P = 2.10E-11) than L- type CCBs. Transmission electron microscopy showed that T- and L-type CCBs caused fewer ultrastructural changes in the myocytes after drug delivery than L-type CCBs. Conclusion T- and L-type CCBs produced less ultra-early and dose-dependent edema, fewer ultrastructural changes in the myocyte, and a greater antihypertensive effect. Proton density mapping combined with arterial cannulation and transmission electron microscopy allowed for quantification of ultra-early and dose-dependent edema, antihypertensive efficacy, and ultrastructural changes in the myocyte. This is important for the evaluation of induced vasodilatory edema.
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Visa A, Shaikh S, Alza L, Herreros J, Cantí C. The Hard-To-Close Window of T-Type Calcium Channels. Trends Mol Med 2019; 25:571-584. [PMID: 31031178 DOI: 10.1016/j.molmed.2019.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 01/03/2023]
Abstract
T-Type calcium channels (TTCCs) are key regulators of membrane excitability, which is the reason why TTCC pharmacology is subject to intensive research in the neurological and cardiovascular fields. TTCCs also play a role in cancer physiology, and pharmacological blockers such as tetralols and dihydroquinazolines (DHQs) reduce the viability of cancer cells in vitro and slow tumor growth in murine xenografts. However, the available compounds are better suited to blocking TTCCs in excitable membranes rather than TTCCs contributing window currents at steady potentials. Consistently, tetralols and dihydroquinazolines exhibit cytostatic/cytotoxic activities at higher concentrations than those required for TTCC blockade, which may involve off-target effects. Gene silencing experiments highlight the targetability of TTCCs, but further pharmacological research is required for TTCC blockade to become a chemotherapeutic option.
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Affiliation(s)
- Anna Visa
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Soni Shaikh
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Lía Alza
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Judit Herreros
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain
| | - Carles Cantí
- Laboratory of Calcium Cell Signaling, IRBLleida-Universitat de Lleida, Rovira Roure, 80, 25198-Lleida, Spain.
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Veronese ML, Gillen LP, Dorval EP, Hauck WW, Waldman SA, Greenberg HE. Effect of Mibefradil on CYP3A4 In Vivo. J Clin Pharmacol 2013; 43:1091-100. [PMID: 14517191 DOI: 10.1177/0091270003256687] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mibefradil, a calcium channel blocker, was removed from the market because of adverse drug interactions with coadministered CYP3A4 substrates. This study examined the effect of mibefradil on the activity of hepatic and intestinal CYP3A4 in vivo, employing the erythromycin breath test (EBT) and oral midazolam pharmacokinetics. This was a two-period, single-blind, placebo-controlled crossover study in which 8 male volunteers were randomized to the order of receiving placebo and a single 100-mg oral dose of mibefradil. Oral midazolam was coadministered with intravenous [14C N-methyl] erythromycin 1 hour after mibefradil/placebo administration. The EBT was performed 20 minutes following erythromycin administration. Blood and urine were collected during the 36 hours following probe drug administration for analysis of midazolam pharmacokinetics. Coadministration of mibefradil increased the Cmax of midazolam 3-fold, the AUC 8- to 9-fold, and the t1/2 4-fold. Mibefradil coadministration decreased the amount of exhaled 14CO2 in 6 of 8 subjects, with a mean decrease of 25%. It was concluded that a single oral dose of mibefradil significantly inhibits CYP3A4 in intestine and liver. These data support that adverse drug interactions involving mibefradil reflect inhibition of CYP3A4 in intestine and liver. Also, they suggest that the EBT, while a valid probe of in vivo hepatic CYP3A4 activity, is a single time point measurement and may be less sensitive than oral midazolam pharmacokinetics in detecting CYP3A4 inhibition.
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Affiliation(s)
- Maria L Veronese
- Division of Clinical Pharmacology, Department of Medicine, Jefferson Medical College, 132 South 10th Street, 1170 Main, Philadelphia, PA 19107, USA
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Evolving therapeutic indications for N-type calcium channel blockers: from chronic pain to alcohol abuse. Future Med Chem 2011; 2:791-802. [PMID: 21426203 DOI: 10.4155/fmc.10.30] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Clinical exploitation of the therapeutic potential of calcium channels has long been limited to L-type blockers for cardiovascular diseases. Recently, N-type blockers have been fully validated for the treatment of chronic pain, following approval of the intrathecally active ziconotide (Prialt(®)). This review describes the successful efforts to broaden the therapeutic scope of this mechanism to other major CNS indications, based on the discovery of N-type blockers orally active against pain. In animal models, the N-type blocker and pain-reducing NP078585 is efficacious against key elements of ethanol dependency, including self-administration and relapse. NP078585 moderately stimulates brain dopamine release without inducing reward or hyperlocomotion. N-type blockers may emerge as a novel class of 'dopamine stabilizers' for the treatment of drug dependency and other neuropsychiatric disorders without the side effects of current therapies.
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Zabkova M, Zabka M, Rodrigues AE. Separation of Racemic Chiral Drugs Using Immobilized CHIRALPAK IA: Methodology for Preparative Scale Development. SEP SCI TECHNOL 2009. [DOI: 10.1080/01496390802590079] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zabka M, Rodrigues AE. Measurement of pore diffusivity of R,S-α-Tetralol enantiomers in chiral adsorbent CHIRALPAK AD by zero length column method. Sep Purif Technol 2007. [DOI: 10.1016/j.seppur.2007.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Li M, Hansen JB, Huang L, Keyser BM, Taylor JT. Towards selective antagonists of T-type calcium channels: design, characterization and potential applications of NNC 55-0396. ACTA ACUST UNITED AC 2006; 23:173-96. [PMID: 16007233 DOI: 10.1111/j.1527-3466.2005.tb00164.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
NNC 55-0396 is a structural analog of mibefradil (Ro 40-5967) that inhibits both T-type and high-voltage-activated (HVA) Ca2+ channels with a higher selectivity for T-type Ca2+ channels. The inhibitory effect of mibefradil on HVA Ca2+ channels can be attributed to a hydrolyzed metabolite of the drug: the methoxy acetate side chain of mibefradil is removed by intracellular enzymes, thus it forms (1S,2S)-2-(2-(N-[(3-benzoimidazol-2-yl)propyl]-N-methylamino)ethyl)-6-fluoro-1,2,3,4-tetrahydro-1-isopropyl-2-naphtyl hydroxy dihydrochloride (dm-mibefradil), which causes potent inhibition of HVA Ca2+ currents. By replacing the methoxy acetate chain of mibefradil with cyclopropanecarboxylate, a more stable analog was developed (NNC 55-0396). The acute IC50 of NNC 55-0396 to block recombinant Cav3.1 T-type channels expressed in HEK293 cells is approximately 7 muM, whereas 100 microM NNC 55-0396 has no detectable effect on high voltage-activated currents in INS-1 cells. Block of T-type Ca2+ current was partially reduced by membrane hyperpolarization and was enhanced at high stimulus frequency. Washing NNC 55-0396 out of the recording chamber did not reverse the T-type Ca2+ current activity, suggesting that the compound dissolves in or passes through the plasma membrane to exert its effect; however, intracellular perfusion of the compound did not block T-type Ca2+ currents, arguing against a cytoplasmic route of action. We conclude that NNC 55-0396, by virtue of its modified structure, does not produce the metabolite that causes inhibition of L-type Ca2+ channel channels, thus rendering it more selective to T-type Ca2+ channels.
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Affiliation(s)
- Ming Li
- Department of Pharmacology SL-83, Tulane University Health Science Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
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12
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Hanck DA, Martin RL, Tytgat J, Ulens C. Newly Cloned Threshold Channels. Compr Physiol 2002. [DOI: 10.1002/cphy.cp020118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Lee DS, Goodman S, Dean DM, Lenis J, Ma P, Gervais PB, Langer A. Randomized comparison of T-type versus L-type calcium-channel blockade on exercise duration in stable angina: results of the Posicor Reduction of Ischemia During Exercise (PRIDE) trial. Am Heart J 2002; 144:60-7. [PMID: 12094189 DOI: 10.1067/mhj.2002.122869] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Mibefradil is a T-type calcium-channel antagonist and arterial vasodilator with negative chronotropic effects. It is not known if T-type calcium-channel blockade is superior to L-type calcium-channel blockade in patients with stable angina pectoris. METHODS A multicenter, randomized, double-blind trial was conducted in patients with documented coronary disease and stable angina to compare a 360 mg dose of diltiazem CD with 100 mg dose of mibefradil. The primary end point was change in time to symptom-limited exercise termination from baseline to 8 weeks. Secondary efficacy parameters included time to onset of persistent ST-segment depression, time to awareness of angina, and change in exercise duration from baseline to 2 and 4 weeks of treatment. RESULTS A total of 121 patients were randomized to mibefradil and 113 to diltiazem CD. At 8 weeks, the increase in exercise duration was 24.5 seconds greater in the mibefradil group (P =.017; 95% CI 4.4-44.7 seconds). At 8 weeks, time to development of > or =1 mm ST-segment depression was greater by 45.3 seconds (P =.0025; 95% CI 16.2-74.5) with mibefradil, but time to development of angina was not significantly different. CONCLUSION T-type calcium-channel antagonism with mibefradil improved treadmill exercise parameters compared with diltiazem in patients with chronic stable angina. Further investigation and development of antagonists of T-type calcium channels with fewer adverse drug interactions is warranted and may be promising in the management of ischemic heart disease.
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Affiliation(s)
- Douglas S Lee
- St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
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Levine TB, Bernink PJ, Caspi A, Elkayam U, Geltman EM, Greenberg B, McKenna WJ, Ghali JK, Giles TD, Marmor A, Reisin LH, Ammon S, Lindberg E. Effect of mibefradil, a T-type calcium channel blocker, on morbidity and mortality in moderate to severe congestive heart failure: the MACH-1 study. Mortality Assessment in Congestive Heart Failure Trial. Circulation 2000; 101:758-64. [PMID: 10683349 DOI: 10.1161/01.cir.101.7.758] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Calcium antagonists have proved disappointing in long-term congestive heart failure (CHF) studies. Mibefradil, a new calcium antagonist that selectively blocks T-type calcium channels, has been shown to be an effective antihypertensive, antianginal, and anti-ischemic agent, and because of its different mechanism of action, it may be beneficial as adjunct therapy in CHF patients. METHODS AND RESULTS This multicenter, randomized, double-blind study compared mibefradil with placebo as adjunct to usual therapy in 2590 CHF patients (NYHA class II to IV; left ventricular fraction <35%). The initial 50-mg daily dose of mibefradil was uptitrated to 100 mg after 1 month and continued up to 3 years. Patients were monitored at 1 week; 1, 2, and 3 months; and every 3 months thereafter. All-cause mortality, cardiovascular mortality, and cardiovascular morbidity/mortality were analyzed by use of the log-rank test (alpha=0.05). Substudies included exercise tolerance, plasma hormone and cytokines, echocardiography, and quality of life. Total mortality was similar between mibefradil- and placebo-treated patients (P=0.151). The 14% increased risk of mortality with mibefradil in the first 3 months was not statistically significant (P=0.093). Treatment groups had similar cardiovascular mortality (P=0.246), cardiovascular morbidity/mortality (P=0.783), and reasons for death or hospitalization. Patients comedicated with mibefradil and antiarrhythmics (class I or III), including amiodarone, had a significantly increased risk of death. Substudies demonstrated no significant differences between treatments. CONCLUSIONS When used as adjunct therapy, mibefradil did not affect the usual outcome of CHF. The potential interaction with antiarrhythmic drugs, especially amiodarone, and drugs associated with torsade de pointes may have contributed to poor outcomes early in the study.
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Affiliation(s)
- T B Levine
- Michigan Institute for Heart Failure and Transplant Care, Botsford General Hospital, Farmington Hills 48336, USA
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15
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Effects of mibefradil on synaptic transmission in the hippocampus and on voltage-dependent currents in isolated hippocampal and thalamic neurons of the rat. NEUROPHYSIOLOGY+ 2000. [DOI: 10.1007/bf02515162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chung O, Hinder M, Sharma AM, Bönner G, Middeke M, Platon J, Unger T. Comparison of the efficacy and safety of losartan (50-100 mg) with the T-type calcium channel blocker mibefradil (50-100 mg) in mild to moderate hypertension. Fundam Clin Pharmacol 2000; 14:31-41. [PMID: 10681072 DOI: 10.1111/j.1472-8206.2000.tb00391.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The objective of this study was to compare the antihypertensive efficacy and safety of losartan and mibefradil. 324 outpatients (57 +/- 9.2 years) with mild to moderate hypertension were randomly allocated in a double-blind fashion to receive 50 mg of losartan or mibefradil once daily p.o. for 6 weeks after 2 weeks of placebo run-in. Titration was then forced to 100 mg of losartan or mibefradil for an additional 6 weeks. Patients were assessed at baseline, 6 and 12 weeks. The primary efficacy variable was change in predose sitting diastolic (SDBP) and systolic (SSBP) blood pressure at 12 weeks. Secondary variables included change in mean 24-hour ambulatory blood pressure and comparison of safety and tolerability. Both treatments lowered SSBP and SDBP at 6 and 12 weeks (week 6: mibefradil -14/-9 mm Hg; losartan -12/-7 mm Hg) (P <0.001). The primary objective, a difference between treatments in reduction of SSBP and SDBP at week 12 could be demonstrated (mibefradil -22/-16 mm Hg; losartan -16/-10 mm Hg) (P=0.003 and P=0.001, respectively). Twenty-four-hour SBP and 24-hour DBP were reduced (P<0.001) within each treatment group at weeks 6 and 12. The secondary objective, a difference between treatments in reduction of 24-hour blood pressure at week 12 could be demonstrated (P<0.001). Twenty-four-hour heart rate was lowered in the mibefradil group at weeks 6 and 12 (P < 0.001). Responder rates at 6 and 12 weeks were 56.2% and 78.5% for mibefradil versus 56.1% and 55.3% for losartan (P = 0.001). Both treatments were equally well tolerated. This study demonstrates that 50 mg losartan is comparably effective to 50 mg mibefradil in the treatment of mild to moderate hypertension with 100 mg mibefradil being more potent than losartan.
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Affiliation(s)
- O Chung
- Institute of Pharmacology, Christian-Albrechts-University, Kiel, Germany.
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Yu DY, Su EN, Cringle SJ, Alder VA, Yu PK, DeSantis L. Systemic and ocular vascular roles of the antiglaucoma agents beta-adrenergic antagonists and Ca2+ entry blockers. Surv Ophthalmol 1999; 43 Suppl 1:S214-22. [PMID: 10416766 DOI: 10.1016/s0039-6257(99)00042-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This review addresses whether the antiglaucoma agents beta-adrenergic antagonists and Ca2+ entry blockers cause vasoactive effects in the retinal and other ocular vasculatures, as they do in other tissues. The potent vasodilating effects of Ca2+ entry blockers on ocular vessels have recently been demonstrated in in vivo and in vitro studies, implying that the maintenance of ocular vascular tone relies almost exclusively on extracellular Ca2+. Ca2+ entry blockers may potentially play a role in relaxing the retinal, long posterior ciliary, and ophthalmociliary arteries to improve the ocular circulation in vascular diseases in which there is considerable vascular tone present. The beta-adrenergic antagonists are discussed with reference to their antihypertensive role, their effect on other vascular beds, and finally what is known of their effect in the ocular vasculature. The emerging evidence that particular selective beta-adrenergic antagonists, such as betaxolol, are also potent Ca2+ channel entry blockers in other vascular beds is presented. Betaxolol has been shown to induce vasodilatation in the retinal and other ocular vascular beds, although studies have shown that beta1-adrenergic receptors are sparse in these vascular beds. This implies that an alternative mechanism must be responsible for betaxolol-induced vasodilatation. Evidence is presented that betaxolol vasodilates via its potent Ca2+ channel entry blocking properties, and its potency and ability to vasodilate are compared with those of nimodipine and timolol, as well as with those of other Ca2+ channel entry blockers. Important areas for future research in this area are discussed.
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Affiliation(s)
- D Y Yu
- Lions Eye Institute and Centre for Ophthalmology and Visual Science, University of Western Australia, Nedlands, Australia
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Becquemont L, Funck-Brentano C, Jaillon P. Mibefradil, a potent CYP3A inhibitor, does not alter pravastatin pharmacokinetics. Fundam Clin Pharmacol 1999; 13:232-6. [PMID: 10226769 DOI: 10.1111/j.1472-8206.1999.tb00344.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dramatic drug-drug interactions have been observed between several HMG-CoA reductase inhibitors and cytochrome P450 3A (CYP3A) inhibitors. The aim of the present study was to investigate the effects of mibefradil, a potent CYP3A inhibitor, on pravastatin pharmacokinetics. 12 healthy volunteers were included in this open-label one-period study. Pravastatin pharmacokinetics (following a single oral dose of 40 mg) was studied in the absence of mibefradil (day 1) and after repeated doses (100 mg/day) of mibefradil (day 8). Pravastatin pharmacokinetics after repeated doses of 40 mg/day was also studied in association with repeated doses (100 mg/day) of mibefradil (day 16). Pravastatin area under the plasma concentration vs. time curve (AUC0-infinity) and Cmax in the absence of mibefradil on day 1 (170 [117 to 395] ng h/mL and 91 [72 to 200] ng/mL respectively, geometric mean [95% confidence intervals]) were not significantly altered in the presence of mibefradil on day 8 (224 [174 to 381] ng h/mL and 124 [72 to 200] ng/mL) and on day 16 (200 [137 to 555] ng h/mL and 91 [74 to 184] ng/mL). Tmax of pravastatin in the absence of mibefradil (0.9 +/- 0.1 h, arithmetic mean +/- SD) was slightly delayed in the presence of mibefradil on day 8 and 16 (1.1 +/- 0.3 and 1.2 +/- 0.3 h respectively, p < 0.01 for both comparisons). The results of the present study confirm the lack of pharmacokinetic interactions between mibefradil and pravastatin and indicate that pravastatin may be safely prescribed in the presence of potent CYP3A inhibitors.
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Affiliation(s)
- L Becquemont
- Service de Pharmacologie, CHU Saint Antoine, Université Paris VI, France
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