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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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Vilarinho KAS, de Oliveira PPM, Saad MJA, Eghtesady P, Filho LMS, Vieira RW, Petrucci O. Erythropoietin protects the systolic function of neonatal hearts against ischaemia/reperfusion injury. Eur J Cardiothorac Surg 2012; 43:156-62. [PMID: 22564802 DOI: 10.1093/ejcts/ezs254] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES The effect of erythropoietin (EPO) on neonatal hearts is not well understood. The current hypothesis is that EPO has protective effects against ischaemia-reperfusion when administered prior to ischaemia induction. METHODS Systolic and diastolic indices, as well as the Akt and extracellular-regulated kinase (Erk) signalling pathways, were studied in vivo using a neonatal pig heart model. Regional ischaemia was induced for 45 min by the ligation of the left anterior descending artery, followed by 90 min of reperfusion. The treatment groups consisted of: (i) untreated controls, (ii) treatment with EPO 3 min prior to ischaemia and (iii) treatment with EPO 24 h before ischaemia. Sophisticated myocardial contractility indices were assessed by pressure/volume loops of the left ventricle. The Akt and Erk pathways were evaluated via a western blot. RESULTS Elastance was found to be higher in the group receiving EPO 3 min prior to ischaemia. In addition, preload recruitable stroke work was higher for both groups receiving EPO prior to ischaemia when compared with controls. The time constant of the isovolumic relaxation and end-diastolic pressure-volume relationship did not differ between the three groups after 90 min of reperfusion. Furthermore, EPO treatment enhanced phosphorylation of Akt, but not Erk, and EPO-treated animals showed lower levels of apoptosis-related proteins. CONCLUSIONS EPO had a protective effect on neonatal systolic function after ischaemia/reperfusion injury, but no effect on diastolic function. This cardioprotective effect might be mediated by the activation of the Akt pathway.
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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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Shmuylovich L, Kovács SJ. Stiffness and relaxation components of the exponential and logistic time constants may be used to derive a load-independent index of isovolumic pressure decay. Am J Physiol Heart Circ Physiol 2008; 295:H2551-9. [PMID: 18952715 DOI: 10.1152/ajpheart.00780.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In current practice, empirical parameters such as the monoexponential time constant tau or the logistic model time constant tauL are used to quantitate isovolumic relaxation. Previous work indicates that tau and tauL are load dependent. A load-independent index of isovolumic pressure decline (LIIIVPD) does not exist. In this study, we derive and validate a LIIIVPD. Recently, we have derived and validated a kinematic model of isovolumic pressure decay (IVPD), where IVPD is accurately predicted by the solution to an equation of motion parameterized by stiffness (Ek), relaxation (tauc), and pressure asymptote (Pinfinity) parameters. In this study, we use this kinematic model to predict, derive, and validate the load-independent index MLIIIVPD. We predict that the plot of lumped recoil effects [Ek.(P*max-Pinfinity)] versus resistance effects [tauc.(dP/dtmin)], defined by a set of load-varying IVPD contours, where P*max is maximum pressure and dP/dtmin is the minimum first derivative of pressure, yields a linear relation with a constant (i.e., load independent) slope MLIIIVPD. To validate the load independence, we analyzed an average of 107 IVPD contours in 25 subjects (2,669 beats total) undergoing diagnostic catheterization. For the group as a whole, we found the Ek.(P*max-Pinfinity) versus tauc.(dP/dtmin) relation to be highly linear, with the average slope MLIIIVPD=1.107+/-0.044 and the average r2=0.993+/-0.006. For all subjects, MLIIIVPD was found to be linearly correlated to the subject averaged tau (r2=0.65), tauL(r2=0.50), and dP/dtmin (r2=0.63), as well as to ejection fraction (r2=0.52). We conclude that MLIIIVPD is a LIIIVPD because it is load independent and correlates with conventional IVPD parameters. Further validation of MLIIIVPD in selected pathophysiological settings is warranted.
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Affiliation(s)
- Leonid Shmuylovich
- Cardiovascular Biophysics Laboratory, Department of Internal Medicine, College of Arts and Sciences, Washington University School of Medicine, 660 S. Euclid Ave., Box 8086, St. Louis, MO 63110, USA
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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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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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