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Mizuno J, Mohri S, Yokoyama T, Otsuji M, Arita H, Hanaoka K. Temperature-dependent inotropic and lusitropic indices based on half-logistic time constants for four segmental phases in isovolumic left ventricular pressure–time curve in excised, cross-circulated canine heart. Can J Physiol Pharmacol 2017; 95:190-198. [DOI: 10.1139/cjpp-2015-0196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Varying temperature affects cardiac systolic and diastolic function and the left ventricular (LV) pressure–time curve (PTC) waveform that includes information about LV inotropism and lusitropism. Our proposed half-logistic (h-L) time constants obtained by fitting using h-L functions for four segmental phases (Phases I–IV) in the isovolumic LV PTC are more useful indices for estimating LV inotropism and lusitropism during contraction and relaxation periods than the mono-exponential (m-E) time constants at normal temperature. In this study, we investigated whether the superiority of the goodness of h-L fits remained even at hypothermia and hyperthermia. Phases I–IV in the isovolumic LV PTCs in eight excised, cross-circulated canine hearts at 33, 36, and 38 °C were analyzed using h-L and m-E functions and the least-squares method. The h-L and m-E time constants for Phases I–IV significantly shortened with increasing temperature. Curve fitting using h-L functions was significantly better than that using m-E functions for Phases I–IV at all temperatures. Therefore, the superiority of the goodness of h-L fit vs. m-E fit remained at all temperatures. As LV inotropic and lusitropic indices, temperature-dependent h-L time constants could be more useful than m-E time constants for Phases I–IV.
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Affiliation(s)
- Ju Mizuno
- Department of Anesthesiology and Pain Medicine, Juntendo University Faculty of Medicine, Tokyo 113-8431, Japan
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558, Japan
- Department of Dental Anesthesiology, Faculty of Dental Science, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
- Department of Anesthesiology and Pain Relief Center, JR Tokyo General Hospital, Tokyo, 151-8528, Japan
| | - Satoshi Mohri
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, 700-8558, Japan
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Takeshi Yokoyama
- Department of Dental Anesthesiology, Faculty of Dental Science, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Mikiya Otsuji
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Hideko Arita
- Department of Anesthesiology and Pain Relief Center, JR Tokyo General Hospital, Tokyo, 151-8528, Japan
| | - Kazuo Hanaoka
- Department of Anesthesiology and Pain Relief Center, JR Tokyo General Hospital, Tokyo, 151-8528, Japan
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Mizuno J, Morita S, Otsuji M, Arita H, Hanaoka K, Akins RE, Hirano S, Kusakari Y, Kurihara S. Half-logistic time constants as inotropic and lusitropic indices for four sequential phases of isometric tension curves in isolated rabbit and mouse papillary muscles. Int Heart J 2009; 50:389-404. [PMID: 19506342 DOI: 10.1536/ihj.50.389] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The waveforms of myocardial tension and left ventricular (LV) pressure curves are useful for evaluating myocardial and LV performance, and especially for inotropism and lusitropism. Recently, we found that half-logistic (h-L) functions provide better fits for the two partial rising and two partial falling phases of the isovolumic LV pressure curve compared to mono-exponential (m-E) functions, and that the h-L time constants for the four sequential phases are superior inotropic and lusitropic indices compared to the m-E time constants. In the present study, we tested the hypothesis that the four sequential phases of the isometric tension curves in mammalian cardiac muscles could be curve-fitted accurately using h-L functions. The h-L and m-E curve-fits were compared for the four phases of the isometric twitch tension curves in 7 isolated rabbit right ventricular and 15 isolated mouse LV papillary muscles. The isometric tension curves were evaluated in the four temporal phases: from the beginning of twitch stimulation to the maximum of the first order time derivative of tension (dF/dt(max)) (Phase I), from dF/dt(max) to the peak tension (Phase II), from the peak tension to the minimum of the first order time derivative of tension (dF/dt(min)) (Phase III), and from dF/dt(min) to the resting tension (Phase IV). The mean h-L correlation coefficients (r) of 0.9958, 0.9996, 0.9995, and 0.9999 in rabbit and 0.9950, 0.9996, 0.9994, and 0.9997 in mouse for Phases I, II, III, and IV, respectively, were higher than the respective m-E r-values (P < 0.001). The h-L function quantifies the amplitudes and time courses of the two partial rising and two partial falling phases of the isometric tension curve, and the h-L time constants for the four partial phases serve as accurate and useful indices for estimation of inotropic and lusitropic effects.
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Affiliation(s)
- Ju Mizuno
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo, Japan
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Mizuno J, Matsubara H, Mohri S, Shimizu J, Suzuki S, Mikane T, Araki J, Hanaoka K, Akins R, Morita S. Half-logistic time constant: a more reliable lusitropic index than monoexponential time constant regardless of temperature in canine left ventricle. Can J Physiol Pharmacol 2008; 86:78-87. [DOI: 10.1139/y08-001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Temperature changes influence cardiac diastolic function. The monoexponential time constant (tauE), which is a conventional lusitropic index of the rate of left ventricular (LV) pressure fall, increases with cooling and decreases with warming. We have proposed that a half-logistic time constant (tauL) is a better lusitropic index than tauE at normothermia. In the present study, we investigated whether tauL can remain a superior measure as temperature varies. The isovolumic relaxation LV pressure curves from the minimum of the first time derivative of LV pressure (dP/dtmin) to the LV end-diastolic pressure were analyzed at 30, 33, 36, 38, and 40 °C in excised, cross-circulated canine hearts. tauL and tauE were evaluated by curve-fitting using the least squares method and applying the half-logistic equation, P(t) = PA/[1 + exp(t/tauL)] + PB, and the monoexponential equation, P(t) = P0exp(–t/tauE) + P∞. Both tauL and tauE increased significantly with decreasing temperature and decreased with increasing temperature. The half-logistic correlation coefficient (r) values were significantly higher than the monoexponential r values at the 5 above-mentioned temperatures. This implies that the superiority of the goodness of the half-logistic fit is not temperature dependent. The half-logistic model characterizes the amplitude and time course of LV pressure fall more reliably than the monoexponential model. Hence, we concluded that tauL is a more useful lusitropic index regardless of temperature.
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Affiliation(s)
- Ju Mizuno
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Hiromi Matsubara
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Satoshi Mohri
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Juichiro Shimizu
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Shunsuke Suzuki
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Takeshi Mikane
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Junichi Araki
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Kazuo Hanaoka
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Robert Akins
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
| | - Shigeho Morita
- Department of Cardiovascular Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
- Molecular Cardiology Laboratory, Nemours Biomedical Research, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA
- Department of Anesthesiology, Teikyo University School of Medicine, Tokyo 173-8605, Japan
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Abstract
The heart is a frequent site of toxicity of pharmaceutical compounds in humans, and when developing a new drug it is critical to conduct a thorough preclinical evaluation of its possible adverse effects on cardiac structure and function. Changes in cardiac morphology such as myocardial necrosis, hypertrophy or valvulopathy are assessed in regulatory toxicity studies in laboratory animals, although specific models may be needed for a more accurate detection of the risk. The potential proarrhythmic risk of new drugs is a major subject of concern and needs to be fully addressed before treatment of volunteers or patients takes place. In vitro assays are conducted to determine the effects on cardiac ion channels, in particular I(Kr) potassium channel antagonism. Prolongation of the QT interval is assessed in vivo, generally in telemetered dogs. Together, these two tests are considered to detect most arrhythmic drugs. The results of this core battery can be refined by additional studies, in particular assays on isolated cardiac tissues determining changes in cardiac action potential duration, shape and variability over time. Triggering of arrhythmia is assessed in hypokalaemic dogs with artificially created bradycardia, or in vitro in isolated whole hearts. The proarrhythmic risk of the new compound is then evaluated by integrating the results of these different tests. Drug adverse effects on cardiac electrophysiological function, in particular impulse formation and conduction, are evaluated through changes in ECG, generally recorded in dogs, pigs or monkeys. Changes in cardiac contractility occurring either as a primary effect of the drug on cardiac function or as a consequence of cardiac lesions should also be carefully assessed. In telemetered or anaesthetised animals, cardiac contractility is evaluated by measurement of left ventricular pressure and its first derivative over time. Echocardiography allows non-invasive measurement of drug-induced changes in ventricular wall movements and cardiac haemodynamics indicative of effects on contractility. In conclusion, a reliable and accurate evaluation of the cardiac safety of a new pharmaceutical agent is based on the results of in vitro tests, with overall moderate to high throughput, and in vivo experiments assessing the effects of the drug on the heart in its physiological environment. The specific sensitivities of the animals used in these assays to cardiac adverse effects should also be considered. The final evaluation of the cardiac risk is therefore based on an integrated analysis of the results from a battery of tests.
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Affiliation(s)
- Gilles Hanton
- Pfizer Global Research and Development, Amboise, France.
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Mizuno J, Otsuji M, Takeda K, Yamada Y, Arita H, Hanaoka K, Hirano S, Kusakari Y, Kurihara S. Superior logistic model for decay of Ca2+ transient and isometric relaxation force curve in rabbit and mouse papillary muscles. Int Heart J 2007; 48:215-32. [PMID: 17409587 DOI: 10.1536/ihj.48.215] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A decrease in myocardial intracellular calcium concentration ([Ca(2+)](i)) precedes relaxation, and a monoexponential function is typically used for fitting the decay of the Ca(2+) transient. However, a logistic function has been shown to be a better fit for the relaxation force curve, compared to the conventional monoexponential function. In the present study, we compared the logistic and monoexponential functions for fitting the [Ca(2+)](i) declines, which were measured using the aequorin method, and isometric relaxation force curves at 4 different onsets: the minimum time-derivative of [Ca(2+)](i) (d[Ca(2+)](i)/dt (min)) and force (dF/dt(min)), and the 10%, 20% and 30% lower [Ca(2+)](i) levels and forces over the data-sampling period in 7 isolated rabbit right ventricular and 15 isolated mouse left ventricular papillary muscles. Logistic functions were significantly superior for fitting the [Ca(2+)] (i) declines and relaxation force curves, compared to monoexponential functions. Changes in the normalized logistic [Ca(2+)] (i) decline and relaxation force time constants at the delayed onsets relative to their 100% values at d[Ca(2+)] (i)/dt(min) and dF/dt(min) were significantly smaller than the changes in the normalized monoexponential time constants. The ratio of the logistic relaxation force time constant relative to the logistic [Ca(2+)](i) decline time constant was significantly smaller in mouse than in rabbit. We conclude that the logistic function more reliably characterizes the [Ca(2+)](i) decline and relaxation force curve at any onset, irrespective of animal species. Simultaneous analyses using the logistic model for decay of the Ca(2+) transient and myocardial lusitropism might be a useful strategy for analysis of species-specific myocardial calcium handling.
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Affiliation(s)
- Ju Mizuno
- Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, Japan
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Mizuno J, Mohri S, Shimizu J, Suzuki S, Mikane T, Araki J, Matsubara H, Morita T, Hanaoka K, Suga H. Starling-Effect-Independent Lusitropism Index in Canine Left Ventricle: Logistic Time Constant. Anesth Analg 2006; 102:1032-9. [PMID: 16551893 DOI: 10.1213/01.ane.0000202537.19646.10] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The logistic time constant (tau(L)) has been proposed as a better index of the rate of left ventricular (LV) relaxation or lusitropism than the conventional monoexponential time constant (tau(E)). However, whether and how the Frank-Starling effect influences tau(L) remains to be elucidated. We compared the effect of LV volume (LVV) loading on both logistic and monoexponential fittings. The isovolumic LV relaxation pressure curves from the maximum negative time derivative of pressure (-dP/dt(max)) were analyzed at 3 different end-points at 4 LVVs of 10, 12, 14, and 16 mL in 8 excised, cross-circulated canine hearts. We found that the logistic fitting was superior to the monoexponential fitting at all LVVs and end-points. LVV loading did not affect tau(L) but affected tau(E) slightly. Although the advancing end-point increased both tau(L) and tau(E), the increases were significantly smaller for tau(L) than for tau(E) at all LVVs. Moreover, the changes in both the amplitude constants and nonzero asymptotes with the advancing end-point were significantly smaller for the logistic fitting than for the monoexponential fitting. We conclude that tau(L) served as a more reliable index of lusitropism that is independent of the change in LVV loading or the Frank-Starling effect.
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Affiliation(s)
- Ju Mizuno
- Departs. of Cardiovascular Physiology, Anesthesiology, and Resuscitology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Scienes, and Depart. of Anesthesiology, The University of Tokyo, Japan. [corrected]
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