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Lertwanakarn T, Suntravat M, Sánchez EE, Wolska BM, Solaro RJ, de Tombe PP, Tachampa K. Negative inotropic mechanisms of β-cardiotoxin in cardiomyocytes by depression of myofilament ATPase activity without activation of the classical β-adrenergic pathway. Sci Rep 2021; 11:21154. [PMID: 34707114 PMCID: PMC8551325 DOI: 10.1038/s41598-021-00282-x] [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: 06/08/2021] [Accepted: 10/06/2021] [Indexed: 11/09/2022] Open
Abstract
Beta-cardiotoxin (β-CTX) from the king cobra venom (Ophiophagus hannah) was previously proposed as a novel β-adrenergic blocker. However, the involvement of β-adrenergic signaling by this compound has never been elucidated. The objectives of this study were to investigate the underlying mechanisms of β-CTX as a β-blocker and its association with the β-adrenergic pathway. The effects of β-CTX on isolated cardiac myocyte functions, calcium homeostasis, the phosphorylation level of targeted proteins, and the myofibrillar ATPase activity were studied. Healthy Sprague Dawley rats were used for cardiomyocytes isolation. Like propranolol, β-CTX attenuated the cardiomyocyte inotropy and calcium transient alterations as induced by isoproterenol stimulation. In contrast, these effects were not observed in forskolin-treated cells. Interestingly, cardiomyocytes treated with β-CTX showed no changes in phosphorylation level at any PKA-targeted sites in the myofilaments as demonstrated in Western blot analysis. The skinned fibers study revealed no change in myofilament kinetics by β-CTX. However, this protein exhibited the direct inhibition of myofibrillar ATPase activity with calcium de-sensitization of the enzyme. In summary, the negative inotropic mechanism of β-CTX was discovered. β-CTX exhibits an atypical β-blocker mechanism. These properties of β-CTX may benefit in developing a novel agent aid to treat hypertrophic cardiomyopathy.
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Affiliation(s)
- Tuchakorn Lertwanakarn
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Montamas Suntravat
- National Natural Toxins Research Center, Texas-A&M University-Kingsville, Kingsville, TX, USA.,Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, USA
| | - Elda E Sánchez
- National Natural Toxins Research Center, Texas-A&M University-Kingsville, Kingsville, TX, USA.,Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, USA
| | - Beata M Wolska
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA.,Department of Medicine, the University of Illinois at Chicago, Chicago, IL, USA
| | - R John Solaro
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA
| | - Pieter P de Tombe
- Department of Physiology and Biophysics, the University of Illinois at Chicago, Chicago, IL, USA.,Phymedexp, Université de Montpellier, Inserm, CNRS, Montpellier, France
| | - Kittipong Tachampa
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
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Ishizaka T, Yoshimatsu Y, Maeda Y, Chiba K, Mori K. Negative lusitropic property of nifekalant identified using ventricular pressure-volume loop analyses in anesthetized monkeys. Exp Anim 2019; 68:91-102. [PMID: 30333366 PMCID: PMC6389513 DOI: 10.1538/expanim.18-0098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The present study was conducted to clarify multiple cardiohemodynamic and
electrophysiological properties including inotropic/lusitropic effects of nifekalant, a
class III antiarrhythmic drug, in an isoflurane-anesthetized monkey. Nifekalant was
administered intravenously at the therapeutic dose of 0.3 mg/kg over 10 min to male
cynomolgus monkeys (n=4), followed by higher dose of 1 (n=3) or 3 mg/kg (n=1) that was
limited due to arrythmogenicity. Left ventricular (LV) pressure-volume (PV) analysis
revealed that the 0.3 mg/kg dose of nifekalant induced a negative lusitropic effect,
recognized as a decrease in maximal rate of reduction in LV pressure and a prolonged
isovolumic relaxation time. Nifekalant also decreased heart rate and increased LV
end-diastolic pressure, but had no effects on the other cardiohemodynamic parameters
examined. Electrophysiological analysis showed nifekalant at 0.3 mg/kg prolonged QT/QTc
intervals with no evidence of arrhythmia. Higher doses of nifekalant induced ventricular
arrhythmia in 3 out of 4 animals, in which both the short-term and long-term variability
of the QT interval increased just before the occurrence of arrhythmia. In conclusion, a
therapeutic dose of nifekalant had no effect on inotropic activity or cardiac compliance,
whereas it showed negative lusitropic properties and QT/QTc prolongation in
isoflurane-anesthetized monkeys. In addition, higher doses of nifekalant showed remarkable
QT/QTc prolongation leading to arrhythmogenicity, which showed good accordance with
clinical findings. Caution should be paid to negative lusitropic properties as well as
arrhythmogenisity for the safe use of nifekalant.
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Affiliation(s)
- Tomomichi Ishizaka
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Yu Yoshimatsu
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Yu Maeda
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Katsuyoshi Chiba
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
| | - Kazuhiko Mori
- Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., 1-16-13 Kita-Kasai, Edogawa-ku, Tokyo 134-8630, Japan
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Castro-Chaves P, Fontes-Carvalho R, Pintalhao M, Pimentel-Nunes P, Leite-Moreira AF. Angiotensin II-induced increase in myocardial distensibility and its modulation by the endocardial endothelium in the rabbit heart. Exp Physiol 2009; 94:665-74. [DOI: 10.1113/expphysiol.2008.046458] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Ladeiras-Lopes R, Ferreira-Martins J, Leite-Moreira AF. Acute neurohumoral modulation of diastolic function. Peptides 2009; 30:419-25. [PMID: 19028535 DOI: 10.1016/j.peptides.2008.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/26/2008] [Accepted: 10/27/2008] [Indexed: 02/07/2023]
Abstract
Diastole plays a central role in cardiovascular homeostasis. Its two main determinants, myocardial relaxation and passive properties of the ventricular wall, are nowadays regarded as physiological mechanisms susceptible of active modulation. Furthermore, diastolic dysfunction and heart failure with normal ejection fraction (previously called diastolic heart failure) are two subjects of major clinical relevance and an intense area of research. The role of several neurohumoral mediators like angiotensin-II and endothelin-1 on the modulation of diastolic function was systematically described as having only chronic deleterious effects such as cardiac hypertrophy and fibrosis. However, over the last years a growing body of evidence described a new role for several peptides on the acute modulation of diastolic function. In the acute setting, some of these mediators may have the potential to induce an adaptive cardiac response. In this review, we describe the role of angiotensin-II, endothelin-1, nitric oxide, urotensin-II and ghrelin on the acute modulation of diastolic function, emphasizing its pathophysiological relevance. Only a thorough understanding of diastolic physiology as well as its active modulation, both in the acute and chronic settings, will improve our knowledge on diastolic dysfunction and allow us to solve the enigmas of heart failure with normal ejection fraction.
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