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Wisialowski TA, Ether N, Foley CM, Kleiman R, Koshman Y, Leishman D, Martel E, Nichols JV, Popp J, Rajamani S, Riley S, Rossman EI, Vargas HM. mproving the in vivo QTc assay: Nonclinical concentration-QTc modeling for risk assessment. J Pharmacol Toxicol Methods 2024:107515. [PMID: 38777240 DOI: 10.1016/j.vascn.2024.107515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 05/03/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Affiliation(s)
| | | | | | | | | | | | - Eric Martel
- Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
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Rossman EI, Wisialowski TA, Vargas HM, Valentin JP, Rolf MG, Roche BM, Riley S, Pugsley MK, Nichols J, Li D, Leishman DJ, Kleiman RB, Greiter-Wilke A, Gintant GA, Engwall MJ, Delaunois A, Authier S. Best practice considerations for nonclinical in vivo cardiovascular telemetry studies in non-rodent species: Delivering high quality QTc data to support ICH E14/S7B Q&As. J Pharmacol Toxicol Methods 2023; 123:107270. [PMID: 37164235 DOI: 10.1016/j.vascn.2023.107270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/02/2023] [Accepted: 05/06/2023] [Indexed: 05/12/2023]
Abstract
The ICH E14/S7B Questions and Answers (Q&As) guideline introduces the concept of a "double negative" nonclinical scenario (negative hERG assay and negative in vivo QTc study) to demonstrate that a drug does not produce a clinically relevant QT prolongation (i.e., no QT liability). This nonclinical "double negative" data package, along with negative Phase 1 clinical QTc data, may be sufficient to substitute for a clinical Thorough QT (TQT) study in some specific cases. While standalone GLP in vivo cardiovascular studies in non-rodent species are standard practice during nonclinical drug development for small molecule programs, a variety of approaches to the design, conduct, analysis and interpretation are utilized across pharmaceutical companies and contract research organizations (CROs) that may, in some cases, negatively impact the stringent sensitivity needed to fulfill the new Q&As. Subject matter experts from both Pharma and CROs have collaborated to recommend best practices for more robust nonclinical cardiovascular telemetry studies in non-rodent species, with input from clinical and regulatory experts. The aim was to increase consistency and harmonization across the industry and to ensure delivery of high quality nonclinical QTc data to meet the proposed sensitivities defined within the revised ICH E14/S7B Q&As guideline (Q&As 5.1 and 6.1). The detailed best practice recommendations presented here cover the design and execution of the safety pharmacology cardiovascular study, including optimal methods for acquiring, analyzing, reporting, and interpreting the resulting QTc and pharmacokinetic data to allow for direct comparison to clinical exposures and assessment of safety margin for QTc prolongation.
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Affiliation(s)
- Eric I Rossman
- GSK, Nonclinical Safety, Safety Pharmacology, Collegeville, PA, USA.
| | - Todd A Wisialowski
- Pfizer Worldwide Research Development and Medical, Safety Pharmacology, Groton, CT, USA
| | - Hugo M Vargas
- Amgen Research, Translational Safety & Bioanalytical Sciences, Thousand Oaks, CA, USA
| | | | - Michael G Rolf
- AstraZeneca, Clinical Pharmacology & Safety Sciences, R&D, Gothenburg, Sweden
| | - Brian M Roche
- Charles River Laboratories, Global Safety Pharmacology, Ashland, OH, USA
| | - Steve Riley
- Pfizer Worldwide Research Development and Medical, Clinical Pharmacology, Groton, CT, USA
| | | | - Jill Nichols
- Labcorp Early Development Laboratories Inc., Madison, WI, USA
| | - Dingzhou Li
- Pfizer Global Product Development, Global Biometrics & Data Management, Groton, CT, USA
| | | | | | | | | | - Michael J Engwall
- Amgen Research, Translational Safety & Bioanalytical Sciences, Thousand Oaks, CA, USA
| | - Annie Delaunois
- UCB Biopharma SRL, Chemin du Foriest, B-1420 Braine-l'Alleud, Belgium
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Vargas HM, Rossman EI, Wisialowski TA, Nichols J, Pugsley MK, Roche B, Gintant GA, Greiter-Wilke A, Kleiman RB, Valentin JP, Leishman DJ. Improving the in Vivo QTc assay: The value of implementing best practices to support an integrated nonclinical-clinical QTc risk assessment and TQT substitute. J Pharmacol Toxicol Methods 2023; 121:107265. [PMID: 36997076 DOI: 10.1016/j.vascn.2023.107265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/19/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023]
Abstract
Recent updates and modifications to the clinical ICH E14 and nonclinical ICH S7B guidelines, which both relate to the evaluation of drug-induced delayed repolarization risk, provide an opportunity for nonclinical in vivo electrocardiographic (ECG) data to directly influence clinical strategies, interpretation, regulatory decision-making and product labeling. This opportunity can be leveraged with more robust nonclinical in vivo QTc datasets based upon consensus standardized protocols and experimental best practices that reduce variability and optimize QTc signal detection, i.e., demonstrate assay sensitivity. The immediate opportunity for such nonclinical studies is when adequate clinical exposures (e.g., supratherapeutic) cannot be safely achieved, or other factors limit the robustness of the clinical QTc evaluation, e.g., the ICH E14 Q5.1 and Q6.1 scenarios. This position paper discusses the regulatory historical evolution and processes leading to this opportunity and details the expectations of future nonclinical in vivo QTc studies of new drug candidates. The conduct of in vivo QTc assays that are consistently designed, executed and analyzed will lead to confident interpretation, and increase their value for clinical QTc risk assessment. Lastly, this paper provides the rationale and basis for our companion article which describes technical details on in vivo QTc best practices and recommendations to achieve the goals of the new ICH E14/S7B Q&As, see Rossman et al., 2023 (this journal).
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Sathish JG, Bhatt S, DaSilva JK, Flynn D, Jenkinson S, Kalgutkar AS, Liu M, Manickam B, Pinkstaff J, Reagan WJ, Shirai N, Shoieb AM, Sirivelu M, Vispute S, Vitsky A, Walters K, Wisialowski TA, Updyke LW. Comprehensive Nonclinical Safety Assessment of Nirmatrelvir Supporting Timely Development of the SARS-COV-2 Antiviral Therapeutic, Paxlovid™. Int J Toxicol 2022; 41:276-290. [PMID: 35603517 PMCID: PMC9125132 DOI: 10.1177/10915818221095489] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
COVID-19 is a potentially fatal infection caused by the SARS-CoV-2 virus. The SARS-CoV-2 3CL protease (Mpro) is a viral enzyme essential for replication and is the target for nirmatrelvir. Paxlovid (nirmatrelvir co-administered with the pharmacokinetic enhancer ritonavir) showed efficacy in COVID-19 patients at high risk of progressing to hospitalization and/or death. Nonclinical safety studies with nirmatrelvir are essential in informing benefit-risk of Paxlovid and were conducted to support clinical development. In vivo safety pharmacology assessments included a nervous system/pulmonary study in rats and a cardiovascular study in telemetered monkeys. Potential toxicities were assessed in repeat dose studies of up to 1 month in rats and monkeys. Nirmatrelvir administration (1,000 mg/kg, p.o.) to male rats produced transient increases in locomotor activity and respiratory rate but did not affect behavioral endpoints in the functional observational battery. Cardiovascular effects in monkeys were limited to transient increases in blood pressure and decreases in heart rate, observed only at the highest dose tested (75 mg/kg per dose b.i.d; p.o.). Nirmatrelvir did not prolong QTc-interval or induce arrhythmias. There were no adverse findings in repeat dose toxicity studies up to 1 month in rats (up to 1,000 mg/kg daily, p.o.) or monkeys (up to 600 mg/kg daily, p.o.). Nonadverse, reversible clinical pathology findings without clinical or microscopic correlates included prolonged coagulation times at ≥60 mg/kg in rats and increases in transaminases at 600 mg/kg in monkeys. The safety pharmacology and nonclinical toxicity profiles of nirmatrelvir support clinical development and use of Paxlovid for treatment of COVID-19.
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Affiliation(s)
- Jean G. Sathish
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Pearl River, NY, USA
| | - Siddhartha Bhatt
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Jamie K. DaSilva
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Declan Flynn
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Stephen Jenkinson
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, San Diego, CA, USA
| | - Amit S. Kalgutkar
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Cambridge, MA, USA
| | - Maggie Liu
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, San Diego, CA, USA
| | | | - Jason Pinkstaff
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, San Diego, CA, USA
| | - William J. Reagan
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Norimitsu Shirai
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Ahmed M. Shoieb
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Madhu Sirivelu
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Cambridge, MA, USA
| | - Saurabh Vispute
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Allison Vitsky
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, San Diego, CA, USA
| | - Karen Walters
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Todd A. Wisialowski
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Groton, CT, USA
| | - Lawrence W. Updyke
- Pfizer Worldwide Research, Development and Medical, Pfizer Inc, Cambridge, MA, USA
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Vargas HM, Rolf MG, Wisialowski TA, Achanzar W, Bahinski A, Bass A, Benson CT, Chaudhary KW, Couvreur N, Dota C, Engwall MJ, Michael Foley C, Gallacher D, Greiter-Wilke A, Guillon JM, Guth B, Himmel HM, Hegele-Hartung C, Ito M, Jenkinson S, Chiba K, Lagrutta A, Levesque P, Martel E, Okai Y, Peri R, Pointon A, Qu Y, Teisman A, Traebert M, Yoshinaga T, Gintant GA, Leishman DJ, Valentin JP. Time for a Fully Integrated Nonclinical-Clinical Risk Assessment to Streamline QT Prolongation Liability Determinations: A Pharma Industry Perspective. Clin Pharmacol Ther 2020; 109:310-318. [PMID: 32866317 PMCID: PMC7891594 DOI: 10.1002/cpt.2029] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/13/2020] [Indexed: 02/03/2023]
Abstract
Defining an appropriate and efficient assessment of drug‐induced corrected QT interval (QTc) prolongation (a surrogate marker of torsades de pointes arrhythmia) remains a concern of drug developers and regulators worldwide. In use for over 15 years, the nonclinical International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) S7B and clinical ICH E14 guidances describe three core assays (S7B: in vitro hERG current & in vivo QTc studies; E14: thorough QT study) that are used to assess the potential of drugs to cause delayed ventricular repolarization. Incorporating these assays during nonclinical or human testing of novel compounds has led to a low prevalence of QTc‐prolonging drugs in clinical trials and no new drugs having been removed from the marketplace due to unexpected QTc prolongation. Despite this success, nonclinical evaluations of delayed repolarization still minimally influence ICH E14‐based strategies for assessing clinical QTc prolongation and defining proarrhythmic risk. In particular, the value of ICH S7B‐based “double‐negative” nonclinical findings (low risk for hERG block and in vivo QTc prolongation at relevant clinical exposures) is underappreciated. These nonclinical data have additional value in assessing the risk of clinical QTc prolongation when clinical evaluations are limited by heart rate changes, low drug exposures, or high‐dose safety considerations. The time has come to meaningfully merge nonclinical and clinical data to enable a more comprehensive, but flexible, clinical risk assessment strategy for QTc monitoring discussed in updated ICH E14 Questions and Answers. Implementing a fully integrated nonclinical/clinical risk assessment for compounds with double‐negative nonclinical findings in the context of a low prevalence of clinical QTc prolongation would relieve the burden of unnecessary clinical QTc studies and streamline drug development.
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Affiliation(s)
- Hugo M Vargas
- Translational Safety & Bioanalytical Sciences, Amgen Research, Thousand Oaks, California, USA
| | - Michael G Rolf
- Research & Development, Clinical Pharmacology & Safety Sciences, AstraZeneca, Gothenburg, Sweden
| | - Todd A Wisialowski
- Global Safety Pharmacology, Pfizer Global Research and Development, Groton, Connecticut, USA
| | | | | | - Alan Bass
- Merck & Co., Inc., Boston, Massachusetts, USA
| | | | | | - Nicolas Couvreur
- Safety Pharmacology, Institute de Recherches Servier, Suresnes, France
| | - Corina Dota
- Research & Development, Chief Medical Officer Organization, AstraZeneca, Gothenburg, Sweden
| | - Michael J Engwall
- Translational Safety & Bioanalytical Sciences, Amgen Research, Thousand Oaks, California, USA
| | - C Michael Foley
- Integrative Pharmacology, Abbvie, Inc, North Chicago, Illinois, USA
| | - David Gallacher
- Global Safety Pharmacology, Janssen Research & Development, Beerse, Belgium
| | | | | | - Brian Guth
- Department of Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | | | | | - Maki Ito
- Japan Pharmaceutical Manufacturers Association, Tokyo, Japan
| | - Stephen Jenkinson
- Global Safety Pharmacology, Pfizer Global Research and Development, San Diego, California, USA
| | - Katsuyoshi Chiba
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | | | - Paul Levesque
- BMS Bristol-Myers Squibb Company, Princeton, New Jersey, USA
| | - Eric Martel
- Department of Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Yoshiko Okai
- Takeda Pharmaceutical Company Ltd., Fujisawa, Kanagawa, Japan
| | - Ravikumar Peri
- Takeda Pharmaceutical Company Ltd., Cambridge, Massachusetts, USA
| | - Amy Pointon
- Research & Development, Clinical Pharmacology & Safety Sciences, AstraZeneca, Cambridge, UK
| | - Yusheng Qu
- Translational Safety & Bioanalytical Sciences, Amgen Research, Thousand Oaks, California, USA
| | - Ard Teisman
- Global Safety Pharmacology, Janssen Research & Development, Beerse, Belgium
| | - Martin Traebert
- Safety Pharmacology, Novartis Institute of Biomedical Research, Basel, Switzerland
| | | | - Gary A Gintant
- Integrative Pharmacology, Abbvie, Inc, North Chicago, Illinois, USA
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Li Z, Mirams GR, Yoshinaga T, Ridder BJ, Han X, Chen JE, Stockbridge NL, Wisialowski TA, Damiano B, Severi S, Morissette P, Kowey PR, Holbrook M, Smith G, Rasmusson RL, Liu M, Song Z, Qu Z, Leishman DJ, Steidl‐Nichols J, Rodriguez B, Bueno‐Orovio A, Zhou X, Passini E, Edwards AG, Morotti S, Ni H, Grandi E, Clancy CE, Vandenberg J, Hill A, Nakamura M, Singer T, Polonchuk L, Greiter‐Wilke A, Wang K, Nave S, Fullerton A, Sobie EA, Paci M, Musuamba Tshinanu F, Strauss DG. General Principles for the Validation of Proarrhythmia Risk Prediction Models: An Extension of the CiPA In Silico Strategy. Clin Pharmacol Ther 2020; 107:102-111. [PMID: 31709525 PMCID: PMC6977398 DOI: 10.1002/cpt.1647] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/06/2019] [Indexed: 12/27/2022]
Abstract
This white paper presents principles for validating proarrhythmia risk prediction models for regulatory use as discussed at the In Silico Breakout Session of a Cardiac Safety Research Consortium/Health and Environmental Sciences Institute/US Food and Drug Administration-sponsored Think Tank Meeting on May 22, 2018. The meeting was convened to evaluate the progress in the development of a new cardiac safety paradigm, the Comprehensive in Vitro Proarrhythmia Assay (CiPA). The opinions regarding these principles reflect the collective views of those who participated in the discussion of this topic both at and after the breakout session. Although primarily discussed in the context of in silico models, these principles describe the interface between experimental input and model-based interpretation and are intended to be general enough to be applied to other types of nonclinical models for proarrhythmia assessment. This document was developed with the intention of providing a foundation for more consistency and harmonization in developing and validating different models for proarrhythmia risk prediction using the example of the CiPA paradigm.
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Gosink MM, Chapin RE, Wilkie D, Davenport S, Kumpf SW, Enerson BE, Houle C, Koza-Taylor P, Wisialowski TA, Lawton MP. Use of Rat Primary Mesenteric Cells for the Prediction of PDE4 Inhibitor Drug-Induced Vascular Injury. Toxicol Sci 2017; 159:42-49. [PMID: 28903491 DOI: 10.1093/toxsci/kfx113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Drug-induced vascular injury (DIVI) in preclinical studies can delay, if not terminate, a drug development program. Clinical detection of DIVI can be very difficult as there are no definitive biomarkers known to reliably detect this disorder in all instances. The preclinical identification of DIVI requires detailed microscopic examination of a wide range of tissues although one of the most commonly affected areas in rats is the mesenteric vasculature. The reason for this predisposition of mesenteric arteries in rats as well as the exact mechanism and cell types involved in the initial development of these lesions have not been fully elucidated. We hypothesized that by using a mixed culture of cells from rat mesenteric tissue, we would be able to identify an RNA expression signature that could predict the invivo development of DIVI. Five compounds designed to inhibit Phosphodiesterase 4 activity (PDE4i) were chosen as positive controls. PDE4i's are well known to induce DIVI in the mesenteric vasculature of rats and there is microscopic evidence that this is associated, at least in part, with a proinflammatory mechanism. We surveyed, by qRT-PCR, the expression of 96 genes known to be involved in inflammation and using a Random-Forest model, identified 12 genes predictive of invivo DIVI outcomes in rats. Using these genes, we were able to cross-validate the ability of the Random-Forest modeling to predict the concentration at which PDE4i caused DIVI invivo.
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Affiliation(s)
- Mark M Gosink
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | | | - Dean Wilkie
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Scott Davenport
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Steven W Kumpf
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Bradley E Enerson
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Christopher Houle
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Petra Koza-Taylor
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
| | - Todd A Wisialowski
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut 06340
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Swanson TA, Conte T, Deeley B, Portugal S, Kreeger JM, Obert LA, Joseph EC, Wisialowski TA, Sokolowski SA, Rief C, Nugent P, Lawton MP, Enerson BE. Hemodynamic Correlates of Drug-induced Vascular Injury in the Rat Using High-frequency Ultrasound Imaging. Toxicol Pathol 2014; 42:784-91. [DOI: 10.1177/0192623314525687] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Several classes of drugs have been shown to cause drug-induced vascular injury (DIVI) in preclinical toxicity studies. Measurement of blood flow and vessel diameter in numerous vessels and across various tissues by ultrasound imaging has the potential to be a noninvasive translatable biomarker of DIVI. Our objective was to demonstrate the utility of high-frequency ultrasound imaging for measuring changes in vascular function by evaluating blood flow and vessel diameter in the superior mesenteric arteries (SMA) of rats treated with compounds that are known to cause DIVI and are known vasodilators in rat: fenoldopam, CI-1044, and SK&F 95654. Blood flow, vessel diameter, and other parameters were measured in the SMA at 4, 8, and 24 hr after dosing. Mild to moderate perivascular accumulations of mononuclear cells, neutrophils in tunica adventitia, and superficial tunica media as well as multifocal hemorrhage and necrosis in the tunica media were found in animals 24 hr after treatment with fenoldopam and SK&F 95654. Each compound caused marked increases in blood flow and shear stress as early as 4 hr after dosing. These results suggest that ultrasound imaging may constitute a functional correlate for the microscopic finding of DIVI in the rat.
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Affiliation(s)
- Terri A. Swanson
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
| | - Teri Conte
- FUJIFILM VisualSonics, Inc., Toronto, Ontario, Canada
| | - Ben Deeley
- FUJIFILM VisualSonics, Inc., Toronto, Ontario, Canada
| | - Susan Portugal
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
| | - John M. Kreeger
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
| | - Leslie A. Obert
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
| | - E. Clive Joseph
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
| | | | | | - Catherine Rief
- Pfizer Worldwide Research and Development, Andover, Massachusetts, USA
| | - Paul Nugent
- Pfizer Worldwide Research and Development, Groton, Connecticut, USA
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Sun SZ, Ramirez D, Gorczyca WP, Foote SC, Hemkens MD, Bassyouni A, Jenkinson S, Wisialowski TA. Translation of L-type calcium channel block: From in vitro assays to in vivo models. J Pharmacol Toxicol Methods 2013. [DOI: 10.1016/j.vascn.2013.01.174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Wolfgang EA, Gorczyca WP, Wisialowski TA. Changes in QRS duration and cardiac conduction time in the anesthetized guinea pig to evaluate functional Nav1.5 channel inhibition. J Pharmacol Toxicol Methods 2011. [DOI: 10.1016/j.vascn.2011.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gribkoff VK, Pieschl RL, Wisialowski TA, Park WK, Strecker GJ, de Jeu MT, Pennartz CM, Dudek FE. A reexamination of the role of GABA in the mammalian suprachiasmatic nucleus. J Biol Rhythms 1999; 14:126-30. [PMID: 10194649 DOI: 10.1177/074873099129000515] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Three independent electrophysiological approaches in hypothalamic slices were used to test the hypothesis that gamma-amino butyric acid (GABA)A receptor activation excites suprachiasmatic nucleus (SCN) neurons during the subjective day, consistent with a recent report. First, multiple-unit recordings during either the subjective day or night showed that GABA or muscimol inhibited firing activity of the SCN population in a dose-dependent manner. Second, cell-attached recordings during the subjective day demonstrated an inhibitory effect of bath- or microapplied GABA on action currents of single SCN neurons. Third, gramicidin perforated-patch recordings showed that bicuculline increased the spontaneous firing rate during the subjective day. Therefore, electrophysiological data obtained by three different experimental methods provide evidence that GABA is inhibitory rather than excitatory during the subjective day.
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Affiliation(s)
- V K Gribkoff
- Department 409, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492, USA
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Gribkoff VK, Pieschl RL, Wisialowski TA, van den Pol AN, Yocca FD. Phase shifting of circadian rhythms and depression of neuronal activity in the rat suprachiasmatic nucleus by neuropeptide Y: mediation by different receptor subtypes. J Neurosci 1998; 18:3014-22. [PMID: 9526018 PMCID: PMC6792592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neuropeptide Y (NPY) has been implicated in the phase shifting of circadian rhythms in the hypothalamic suprachiasmatic nucleus (SCN). Using long-term, multiple-neuron recordings, we examined the direct effects and phase-shifting properties of NPY application in rat SCN slices in vitro (n = 453). Application of NPY and peptide YY to SCN slices at circadian time (CT) 7.5-8.5 produced concentration-dependent, reversible inhibition of cell firing and a subsequent significant phase advance. Several lines of evidence indicated that these two effects of NPY were mediated by different receptors. NPY-induced inhibition and phase shifting had different concentration-response relationships and very different phase-response relationships. NPY-induced phase advances, but not inhibition, were blocked by the GABAA antagonist bicuculline, suggesting that NPY-mediated modulation of GABA may be an underlying mechanism whereby NPY phase shifts the circadian clock. Application of the Y2 receptor agonists NPY 13-36 and (Cys2,8-aminooctanoic acid5,24,D-Cys27)-NPY advanced the peak of the circadian rhythm but did not inhibit cell firing. The Y1 and Y5 agonist [Leu31,Pro34]-NPY evoked a substantial inhibition of discharge but did not generate a phase shift. NPY-induced inhibition was not blocked by the specific Y1 antagonist BIBP-3226; the antagonist also had no effect on the timing of the peak of the circadian rhythm. Application of the Y5 agonist [D-Trp32]-NPY produced only direct neuronal inhibition. These are the first data to indicate that at least two functional populations of NPY receptors exist in the SCN, distinguishable on the basis of pharmacology, each mediating a different physiological response to NPY application.
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Affiliation(s)
- V K Gribkoff
- Neuroscience Drug Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, Connecticut 06492, USA
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Abstract
BACKGROUND Impulse propagation in the ventricle depends on both sodium channel availability and cell-to-cell coupling through gap junctions. Sodium channel block has been shown to depress conduction velocity (theta) more longitudinal (LONG) to than transverse (TRANS) to fiber orientation. Because exposure to CO2 produces intracellular acidosis and decreased gap junction conductance in vitro, we tested the hypothesis that increased PCO2 would result in preferential depression of transverse conduction in vivo. METHODS AND RESULTS In anesthetized dogs, when atrial pH was reduced to 6.70 +/- 0.04 by increasing the fraction of inhaled CO2 to 40%, theta TRANS fell from 0.23 +/- 0.04 to 0.19 +/- 0.02 m/s (-16 +/- 8%, P < .03), while theta LONG was unchanged (-3 +/- 7%, P = NS). In contrast, with the same degree of acidemia produced by HCl infusion, only theta LONG fell (-8 +/- 7%), coincident with a rise in serum K+. CONCLUSIONS The observed effect of CO2 on propagation in the intact heart is consistent with its previously described in vitro actions to uncouple cell-to-cell communication and may provide a model to study the role of cell-to-cell coupling in normal and abnormal propagation.
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Affiliation(s)
- V R Vorperian
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tenn
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14
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Turgeon J, Wisialowski TA, Wong W, Altemeier WA, Wikswo JP, Roden DM. Suppression of longitudinal versus transverse conduction by sodium channel block. Effects of sodium bolus. Circulation 1992; 85:2221-6. [PMID: 1317273 DOI: 10.1161/01.cir.85.6.2221] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Arrhythmias resulting from treatment with sodium channel-blocking antiarrhythmic drugs have been successfully treated with sodium infusion, although the mechanism underlying this effect is uncertain. METHODS AND RESULTS In this study, we used a multielectrode array to examine the effects of O-desmethyl encainide (ODE), a potent sodium channel-blocking metabolite of encainide, on conduction in canine ventricle. ODE depressed both longitudinal and transverse conduction velocities in a plasma concentration-related fashion (r = -0.74, -0.60; p less than 0.001). At ODE concentrations less than or equal to 300 ng/ml (n = 34), conduction velocity was depressed to the same extent in the longitudinal (-21.9 +/- 8.4%, SD) and transverse orientations (-22.0 +/- 8.8%). However, at concentrations greater than 300 ng/ml (n = 17), conduction was significantly more impaired longitudinally than transversely (-44.5 +/- 11.7% versus -34.4 +/- 13.7%, p less than 0.02). In 12 animals with high concentrations (mean, 432 +/- 32 ng/ml), a 5-meq/kg bolus of sodium chloride over 1 minute immediately increased conduction velocity; this effect was significantly greater and longer lasting in the longitudinal orientation. In two animals, conduction block in the longitudinal orientation was documented at high plasma ODE and was immediately reversed by sodium bolus. CONCLUSIONS We conclude that the major effect of sodium in animals with excess sodium channel block is improvement of longitudinal propagation; this effect may underlie the antiarrhythmic action of sodium in the analogous clinical setting.
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Affiliation(s)
- J Turgeon
- Department of Pharmacology, Vanderbilt University, Nashville, Tenn. 37232-6602
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15
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Wikswo JP, Wisialowski TA, Altemeier WA, Balser JR, Kopelman HA, Roden DM. Virtual cathode effects during stimulation of cardiac muscle. Two-dimensional in vivo experiments. Circ Res 1991; 68:513-30. [PMID: 1991354 DOI: 10.1161/01.res.68.2.513] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We have found that when suprathreshold cathodal stimuli were applied to the epicardium of canine ventricle, impulse propagation originated at a "virtual cathode" with dimensions greater than those of the physical cathode. We report the two-dimensional geometry of the virtual cathode as a function of stimulus strength; the results are compared with the predictions of an anisotropic, bidomain model of cardiac conduction recently developed in our laboratories. Data were collected in six pentobarbital-anesthetized dogs by using a small plaque electrode sewn to the left ventricular epicardium. Arrival times at closely spaced bipolar electrodes oriented radially around a central cathode were obtained as a function of stimulus strength and fiber orientation. The dimensions of the virtual cathode were determined by linear back-extrapolation of arrival times to the time of stimulation. The directional dependence of the conduction velocity was consistent with previous reports: at 1 mA, longitudinal (0 degree) and transverse (90 degrees) velocities were 0.60 +/- 0.03 and 0.29 +/- 0.02 m/sec, respectively. At 7 mA, the longitudinal velocity was 0.75 +/- 0.05 m/sec, whereas there was no significant change in the transverse velocity. In contrast to conduction velocity, the virtual cathode was smallest in the longitudinal orientation and largest between 45 degrees and 60 degrees. Virtual cathode size was dependent on both orientation and stimulus strength: at 0 degree, the virtual cathode was small (approximately 1 mm) and relatively constant over the range of 1-7 mA; at oblique orientations (45 degrees-90 degrees), it displayed a roughly logarithmic dependence on stimulus strength, approximately 1 mm at 1 mA and approximately 3 mm at 7 mA. The bidomain, anisotropic model reproduced both the stimulus strength and the fiber-orientation dependence of the virtual cathode geometry when the intracellular and extracellular anisotropies were 10:1 and 4:1, respectively, but not when the two anisotropies were equal. We suggest that the virtual cathode provides a direct measure of the determinants of cardiac activation; its complex geometry appears to reflect the bidomain, anisotropic nature of cardiac muscle.
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Affiliation(s)
- J P Wikswo
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235
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