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Lookin O, Boulali N, Cazorla O, de Tombe P. Impact of stretch on sarcomere length variability in isolated fully relaxed rat cardiac myocytes. Pflugers Arch 2023; 475:1203-1210. [PMID: 37603101 DOI: 10.1007/s00424-023-02848-2] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/24/2023] [Accepted: 08/05/2023] [Indexed: 08/22/2023]
Abstract
The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling mechanism (FSM). It is based on preload-dependent activation of sarcomeres-the elementary contractile units in muscle cells. Recent findings show a natural variability in sarcomere length (SL) in resting cardiomyocytes that, moreover, is altered in an actively contracting myocyte. SL variability may contribute to the FSM, but it remains unresolved whether the change in the SL variability is regulated by activation process per se or simply by changes in cell stretch, i.e., average SL. To separate the roles of activation and SL, we characterized SL variability in isolated, fully relaxed rat ventricular cardiomyocytes (n = 12) subjected to a longitudinal stretch with the carbon fiber (CF) technique. Each cell was tested in three states: without CF attachment (control, no preload), with CF attachment without stretch, and with CF attachment and ~ 10% stretch of initial SL. The cells were imaged by transmitted light microscopy to retrieve and analyze individual SL and SL variability off-line by multiple quantitative measures such as coefficient of variation or median absolute deviation. We found that CF attachment without stretch did not affect the extent of SL variability nor average SL. In stretched myocytes, the averaged SL significantly increased, while the SL variability remained unchanged. This result clearly indicates that the non-uniformity of individual SL is not sensitive to the average SL itself in fully relaxed myocytes. We conclude that SL variability per se does not contribute to the FSM in the heart.
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Affiliation(s)
| | - Najlae Boulali
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France
| | - Olivier Cazorla
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France
| | - Pieter de Tombe
- Laboratoire "Physiologie Et Médecine Expérimentale du Coeur Et Des Muscles," Phymedexp, INSERM, CNRS, Montpellier University, CHU Arnaud de Villeneuve, 34295, Montpellier, France.
- Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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Lookin O, Boulali N, Cazorla O, Tombe P. Impact of stretch on sarcomere length variability in isolated fully relaxed rat cardiac myocytes. Res Sq 2023:rs.3.rs-3043911. [PMID: 37398289 PMCID: PMC10312908 DOI: 10.21203/rs.3.rs-3043911/v1] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The contractility of cardiac muscle is greatly affected by preload via the Frank-Starling Mechanism (FSM). It is based on the preload-dependent activation of sarcomeres - the elementary contractile units in muscle cells. Recent findings show a natural variability in sarcomere length (SL) in resting cardiomyocytes that, moreover, is altered in an actively contracting myocyte. SL variability may contribute to the FSM but it remains unresolved whether the change in the SL variability is regulated by activation process per se or simply by changes in cell stretch, i.e. average SL. To separate the roles of activation and SL, we characterized SL variability in isolated fully relaxed rat ventricular cardiomyocytes ( n = 12) subjected to a longitudinal stretch with the carbon fiber (CF) technique. Each cell was tested in three states: without CF attachment (control, no preload), with CF attachment without stretch, and with CF attachment and ~ 10% stretch of initial SL. The cells were imaged by transmitted light microscopy to retrieve and analyze individual SL and SL variability off-line by multiple quantitative measures like coefficient of variation or median absolute deviation. We found that CF attachment without stretch did not affect the extent of SL variability and averaged SL. In stretched myocytes, the averaged SL significantly increased while the SL variability remained unchanged. This result clearly indicates that the non-uniformity of individual SL is not sensitive to the average SL itself in fully relaxed myocytes. We conclude that SL variability per se does not contribute to the FSM in the heart.
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Affiliation(s)
| | - Najlae Boulali
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
| | - Olivier Cazorla
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
| | - Pieter Tombe
- Université de Montpellier, INSERM, CNRS, CHU Arnaud de Villeneuve
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Lookin O, Balakin A, Protsenko Y. Differences in Effects of Length-Dependent Regulation of Force and Ca 2+ Transient in the Myocardial Trabeculae of the Rat Right Atrium and Ventricle. Int J Mol Sci 2023; 24:ijms24108960. [PMID: 37240302 DOI: 10.3390/ijms24108960] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
The comparative differences in the fundamental mechanisms of contractility regulation and calcium handling of atrial and ventricular myocardium remain poorly studied. An isometric force-length protocol was performed for the entire range of preloads in isolated rat right atrial (RA) and ventricular (RV) trabeculae with simultaneous measurements of force (Frank-Starling mechanism) and Ca2+ transients (CaT). Differences were found between length-dependent effects in RA and RV muscles: (a) the RA muscles were stiffer, faster, and presented with weaker active force than the RV muscles throughout the preload range; (b) the active/passive force-length relationships were almost linear for the RA and RV muscles; (c) the value of the relative length-dependent growth of passive/active mechanical tension did not differ between the RA and RV muscles; (d) the time-to-peak and amplitude of CaT did not differ between the RA and RV muscles; (e) the CaT decay phase was essentially monotonic and almost independent of preload in the RA muscles, but not in the RV muscles. Higher peak tension, prolonged isometric twitch, and CaT in the RV muscle may be the result of higher Ca2+ buffering by myofilaments. The molecular mechanisms that constitute the Frank-Starling mechanism are common in the rat RA and RV myocardium.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
| | - Alexander Balakin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
| | - Yuri Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., 620049 Yekaterinburg, Russia
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Lookin O, de Tombe P, Boulali N, Gergely C, Cloitre T, Cazorla O. Cardiomyocyte sarcomere length variability: Membrane fluorescence versus second harmonic generation myosin imaging. J Gen Physiol 2023; 155:213827. [PMID: 36695814 PMCID: PMC9930136 DOI: 10.1085/jgp.202213289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/07/2022] [Accepted: 01/10/2023] [Indexed: 01/26/2023] Open
Abstract
Sarcomere length (SL) and its variation along the myofibril strongly regulate integrated coordinated myocyte contraction. It is therefore important to obtain individual SL properties. Optical imaging by confocal fluorescence (for example, using ANEPPS) or transmitted light microscopy is often used for this purpose. However, this allows for the visualization of structures related to Z-disks only. In contrast, second-harmonic generation (SHG) microscopy visualizes A-band sarcomeric structures directly. Here, we compared averaged SL and its variability in isolated relaxed rat cardiomyocytes by imaging with ANEPPS and SHG. We found that SL variability, evaluated by several absolute and relative measures, is two times smaller using SHG vs. ANEPPS, while both optical methods give the same average (median) SL. We conclude that optical methods with similar optical spatial resolution provide valid estimations of average SL, but the use of SHG microscopy for visualization of sarcomeric A-bands may be the "gold standard" for evaluation of SL variability due to the absence of optical interference between the sarcomere center and non-sarcomeric structures. This contrasts with sarcomere edges where t-tubules may not consistently colocalize to Z-disks. The use of SHG microscopy instead of fluorescent imaging can be a prospective tool to map sarcomere variability both in vitro and in vivo conditions and to reveal its role in the functional behavior of living myocardium.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology , Ural Branch of Russian Academy of Sciences , Yekaterinburg, Russia
| | - Pieter de Tombe
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France.,Physiology and Biophysics, University of Illinois at Chicago , Chicago, IL, USA
| | - Najlae Boulali
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France
| | - Csilla Gergely
- L2C, University of Montpellier , CNRS , Montpellier, France
| | | | - Olivier Cazorla
- Laboratory "Physiologie et Médecine Expérimentale du Coeur et des Muscles", Phymedexp, INSERM, CNRS, Montpellier University , Montpellier, France
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Lookin O, Protsenko Y. The Slow Force Response and Simultaneous Changes in Ca2+ Transient in Healthy and Failing Rat Atrial and Ventricular Myocardium. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022070043] [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: 02/11/2023]
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Lookin O, Khokhlova A, Myachina T, Butova X, Cazorla O, de Tombe P. Contractile State Dependent Sarcomere Length Variability in Isolated Guinea-Pig Cardiomyocytes. Front Physiol 2022; 13:857471. [PMID: 35444559 PMCID: PMC9013801 DOI: 10.3389/fphys.2022.857471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/11/2022] [Indexed: 11/13/2022] Open
Abstract
Cardiomyocytes contract keeping their sarcomere length (SL) close to optimal values for force generation. Transmural heterogeneity in SL across the ventricular wall coordinates the contractility of the whole-ventricle. SL heterogeneity (variability) exists not only at the tissue (macroscale) level, but also presents at the level of a single cardiomyocyte (microscale level). However, transmural differences in intracellular SL variability and its possible dependence on the state of contraction (e.g. end-diastole or end-systole) have not been previously reported. In the present study, we studied three aspects of sarcomere-to-sarcomere variability in intact cardiomyocytes isolated from the left ventricle of healthy guinea-pig: 1) transmural differences in SL distribution between subepi- (EPI) and subendocardial (ENDO) cardiomyocytes; 2) the dependence of intracellular variability in SL upon the state of contraction; 3) local differences in SL variability, comparing SL distributions between central and peripheral regions within the cardiomyocyte. To characterize the intracellular variability of SL, we used different normality tests for the assessment of SL distributions, as well as nonparametric coefficients to quantify the variability. We found that individual SL values in the end-systolic state of contraction followed a normal distribution to a lesser extent as compared to the end-diastolic state of contraction (∼1.3-fold and ∼1.6-fold in ENDO and EPI, respectively). The relative and absolute coefficients of sarcomere-to-sarcomere variability in end-systolic SL were significantly greater (∼1.3-fold) as compared to end-diastolic SL. This was independent of both the transmural region across the left ventricle and the intracellular region within the cardiomyocyte. We conclude that the intracellular variability in SL, which exists in normal intact guinea-pig cardiomyocytes, is affected by the contractile state of the myocyte. This phenomenon may play a role in inter-sarcomere communication in the beating heart.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia
- *Correspondence: Oleg Lookin,
| | - Anastasia Khokhlova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia
| | - Tatiana Myachina
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia
| | - Xenia Butova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia
| | - Olivier Cazorla
- Laboratoire “Physiologie et Médecine Expérimentale du Coeur et des Muscles”, Phymedexp, INSERM—CNRS - Montpellier University, Montpellier, France
| | - Pieter de Tombe
- Laboratoire “Physiologie et Médecine Expérimentale du Coeur et des Muscles”, Phymedexp, INSERM—CNRS - Montpellier University, Montpellier, France
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, United States
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Lookin O, Kuznetsov D, Protsenko Y. Omecamtiv mecarbil attenuates length-tension relationship in healthy rat myocardium and preserves it in monocrotaline-induced pulmonary heart failure. Clin Exp Pharmacol Physiol 2021; 49:84-93. [PMID: 34459025 DOI: 10.1111/1440-1681.13584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/24/2021] [Accepted: 08/26/2021] [Indexed: 01/10/2023]
Abstract
The cardiac-specific myosin activator, omecamtiv mecarbil (OM), is an effective inotrope for treating heart failure but its effects on active force and Ca2+ kinetics in healthy and diseased myocardium remain poorly studied. We tested the effect of two concentrations of OM (0.2 and 1 µmol/L in saline) on isometric contraction and Ca-transient (CaT) in right ventricular trabeculae of healthy rats (CONT, n = 8) and rats with monocrotaline-induced pulmonary heart failure (MCT, n = 8). The contractions were obtained under preload of 75%-100% of optimal length (tension-length relationship). The 0.2 µmol/L OM did not affect the diastolic level, amplitude, or kinetics of isometric contraction and CaT, irrespective of the group of rats or preload. The 1 µmol/L OM significantly suppressed active tension-length relationships in CONT but not in MCT, while leading in both groups to a significantly prolonged relaxation. CaT time-to-peak was unaffected in CONT and MCT, but CaT decay was slightly accelerated in its early phase and considerably prolonged in its late phase to a similar extent in both groups. We conclude that the substantial prolongation of CaT decay is due to enhanced Ca2+ utilisation by troponin C mediated by the direct effect of OM on the cooperative activation of myofilaments. The lack of beneficial effect of OM in the healthy rat myocardium may be due to a relatively high level of activating Ca2+ in cells with normal Ca2+ handling, whereas the preservation of the tension-length relationship in the failing heart may relate to the diminished Ca2+ levels of sarcoplasmic reticulum.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Daniil Kuznetsov
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
| | - Yuri Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation
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Lookin O. The use of Ca-transient to evaluate Ca 2+ utilization by myofilaments in living cardiac muscle. Clin Exp Pharmacol Physiol 2020; 47:1824-1833. [PMID: 32654202 DOI: 10.1111/1440-1681.13376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/15/2020] [Accepted: 07/08/2020] [Indexed: 12/20/2022]
Abstract
The kinetics of Ca2+ interaction with myofilaments is an important determinant of the preload-dependent effects on myocardial contractility (the Frank-Starling Mechanism). However, the direct evaluation of this interaction in intact tissue is limited. To overcome this issue, the method of difference curve was proposed, which implements the subtraction of the referent Ca-transient (measured in non-stretched muscle) from the Ca-transients measured at different preloads. This method was tested on the cardiac trabeculae of healthy (CONT) and monocrotaline-treated rats (MCT), subjected to force-length protocol with simultaneous measurement of isometric twitch and Ca-transient. The difference curve had two components, C2 and C3, which are distinct in their directions and, as hypothesized, may reflect mainly the kinetics of Ca2+ utilization by and release from myofilaments, respectively. Both the components were quantitatively evaluated by their amplitude, integral magnitude and time-to-peak. The C3 component in either CONT or MCT was significantly higher in its amplitude/integral magnitude vs the C2 component, at any preload (P < .05). The time-to-peak value was preload-dependent only for the C3 component. There were tight relationships between the above characteristics of C2/C3 components and the characteristics of isometric tension (peak value, time-to-peak and the maximal rates of rise/decline) in CONT and MCT muscles. The C3 component was highly consistent with tension relaxation (Ca2+ release from myofilaments), but the C2 component was partially consistent with tension development (Ca2+ utilization by myofilaments). The novel method of the analysis of Ca-transients can be utilized for indirect evaluation of Ca2+ interaction with myofilaments in healthy and diseased myocardium.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russian Federation.,The Center for Fundamental Biotechnology and Bioengineering, Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg, Russian Federation
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Lookin O, Butova X, Protsenko Y. The role of pacing rate in the modulation of mechano-induced immediate and delayed changes in the force and Ca-transient of cardiac muscle. Prog Biophys Mol Biol 2020; 159:34-45. [PMID: 32450183 DOI: 10.1016/j.pbiomolbio.2020.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/11/2020] [Accepted: 05/11/2020] [Indexed: 12/21/2022]
Abstract
Myocardial function is tuned by dynamic changes in length and load via mechano-calcium feedback. This regulation may be significantly affected by heart rhythm. We evaluated the mechano-induced modulation of contractility and Ca-transient (CaT) in the rat myocardium subjected to twitch-by-twitch shortening-re-lengthening (↓-↑) trains of different lengths (N = 1 … 720 cycles) at low (1 Hz) and near-physiological (3.5 Hz) pacing rates. Force/CaT characteristics were evaluated in the first post-train isometric twitch (immediate effect) and during slow changes (delayed maximal elevation/decrease) and compared with those of the pre-train twitch. The immediate inotropic effect was positive for N = 30 … 720 and negative for N = 1 … 20, while the delayed effect was always positive. The immediate and delayed inotropic effects were significantly higher at 3.5-Hz vs 1-Hz (P < 0.05). The prominent inotropism was accompanied by much smaller changes in the CaT diastolic level/amplitude. The shortening-re-lengthening train induced oscillations of the slow change in force at 3.5-Hz (always) and at 1-Hz (∼50% of muscles), which were dependent of the train length and independent of the pacing rate. We suggest that twitch-by-twitch shortening-re-lengthening of cardiac muscle decreases Ca2+ buffering by troponin C and elevates Ca2+ loading of the sarcoplasmic reticulum (SR); the latter cumulatively depends on the train length. A high pacing rate intensifies the cumulative transient shift in the SR Ca2+ loading, augmenting the post-train inotropic response and prolonging its recovery to the pre-train level. The pacing-dependent mechano-induced inotropic effects remain to be elucidated in the myocardium with impaired Ca handling.
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Affiliation(s)
- Oleg Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049, 106 Pervomayskaya St., Yekaterinburg, Russia; Center for Fundamental Biotechnology and Bioengineering, Institute of Natural Sciences and Mathematics, Ural Federal University, 620002, 19 Mira St., Yekaterinburg, Russia.
| | - Xenia Butova
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049, 106 Pervomayskaya St., Yekaterinburg, Russia; Center for Fundamental Biotechnology and Bioengineering, Institute of Natural Sciences and Mathematics, Ural Federal University, 620002, 19 Mira St., Yekaterinburg, Russia
| | - Yuri Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049, 106 Pervomayskaya St., Yekaterinburg, Russia
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Lookin O, Protsenko Y. Length-Dependent Activation of Contractility and Ca-Transient Kinetics in Auxotonically Contracting Isolated Rat Ventricular Cardiomyocytes. Front Physiol 2019; 10:1473. [PMID: 31920687 PMCID: PMC6917588 DOI: 10.3389/fphys.2019.01473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/14/2019] [Indexed: 11/13/2022] Open
Abstract
Length-dependent activation (LDA) of contraction is an important mechanism of proper myocardial function that is often blunted in diseases accompanied by deficient contractility and impaired calcium homeostasis. We evaluated how the extent of LDA is related to the decreased force in healthy rat myocardium under negative inotropic conditions that affect the calcium cycle. The length-dependent effects on auxotonic twitch and Ca-transient were compared in isolated rat ventricular cardiomyocytes at room temperature (“25C”) and near-physiological temperature (“35C”) in normal Tyrode and at 25°C with thapsigargin-depleted sarcoplasmic reticulum (“25C + Thap”). At the slack length, a similar negative inotropy in “35C” and “25C + Thap” was accompanied by totally different changes in Ca-transient amplitude, time-to-peak, and time-to-decline from peak to 50% amplitude. End-systolic/end-diastolic tension-sarcomere length relationships were obtained for each individual cell, and the ratio of their slopes, the dimensionless Frank-Starling Gain index, was 2.32 ± 0.16, 1.78 ± 0.09, and 1.37 ± 0.06 in “25C,” “35C” and “25C + Thap,” respectively (mean ± S.E.M.). Ca-transient diastolic level and amplitude did not differ between “25C” and “35C” at any SL, but in “35C” it developed and declined significantly faster. In contrast, thapsigargin-induced depletion of SERCA2a significantly attenuated and retarded Ca-transient. The relative amount of Ca2+ utilized by troponin C, evaluated by the integral magnitude of a short-lived component of Ca-transient decline (“bump”), increased by ~25% per each 0.05 μm increase in SL in all groups. The kinetics of the Ca-TnC dissociation, evaluated by the bump time-to-peak, was significantly faster in “35C” and slower in “25C + Thap” vs. “25C” (respectively, 63.7 ± 5.3 and 253.6 ± 8.3% of the value in “25C,” mean ± S.E.M.). In conclusion, a similar inotropic effect can be observed in rat ventricular myocardium under totally different kinetics of free cytosolic calcium. The extent of LDA is not determined by actual peak systolic tension but is regulated by the level of peak systolic calcium and the kinetics of Ca-transient decline which, in turn, are governed by Ca-TnC dissociation and Ca2+ reuptake by the sarcoplasmic reticulum. Altogether, these findings constitute new evidence about the role of the length-dependent modulation of Ca2+ homeostasis in the mechanisms of calcium regulation of contraction and mechano-calcium feedback in the myocardium.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia.,Center for Fundamental Biotechnology and Bioengineering, Institute of Natural Sciences and Mathematics, Ural Federal University, Yekaterinburg, Russia
| | - Yuri Protsenko
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, Russia
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Lookin O, Protsenko Y. The lack of slow force response in failing rat myocardium: role of stretch-induced modulation of Ca-TnC kinetics. J Physiol Sci 2019; 69:345-357. [PMID: 30560346 PMCID: PMC10717443 DOI: 10.1007/s12576-018-0651-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/08/2018] [Indexed: 10/27/2022]
Abstract
The slow force response (SFR) to stretch is an important adaptive mechanism of the heart. The SFR may result in ~ 20-30% extra force but it is substantially attenuated in heart failure. We investigated the relation of SFR magnitude with Ca2+ transient decay in healthy (CONT) and monocrotaline-treated rats with heart failure (MCT). Right ventricular trabeculae were stretched from 85 to 95% of optimal length and held stretched for 10 min at 30 °C and 1 Hz. Isometric twitches and Ca2+ transients were collected on 2, 4, 6, 8, 10 min after stretch. The changes in peak tension and Ca2+ transient decay characteristics during SFR were evaluated as a percentage of the value measured immediately after stretch. The amount of Ca2+ utilized by TnC was indirectly evaluated using the methods of Ca2+ transient "bump" and "difference curve." The muscles of CONT rats produced positive SFR and they showed prominent functional relation between SFR magnitude and the magnitude (amplitude, integral intensity) of Ca2+ transient "bump" and "difference curve." The myocardium of MCT rats showed negative SFR to stretch (force decreased in time) which was not correlated well with the characteristics of Ca2+ transient decay, evaluated by the methods of "bump" and "difference curve." We conclude that the intracellular mechanisms of Ca2+ balancing during stretch-induced slow adaptation of myocardial contractility are disrupted in failing rat myocardium. The potential significance of our findings is that the deficiency of slow force response in diseased myocardium may be diminished under augmented kinetics of Ca-TnC interaction.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation.
- Ural Federal University, 19 Mira St., Yekaterinburg, 620002, Russian Federation.
| | - Yuri Protsenko
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation
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Lookin O, Protsenko Y. P940The deficiency in slow force response to sudden stretch in failing rat myocardium is associated with altered stretch-dependent modulation of Ca-TnC kinetics. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy564.p940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- O Lookin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Science, Ekaterinburg, Russian Federation
| | - Y Protsenko
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Science, Ekaterinburg, Russian Federation
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Myachina T, Khokhlova A, Antsygin I, Lookin O. An Approach for Improvement of Carbon Fiber Technique to Study Cardiac Cell Contractility. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1757-899x/350/1/012011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Lookin O, Balakin A, Protsenko Y. Inhibition of AT1 receptors by losartan affects myocardial slow force response in healthy but not in monocrotaline-treated young rats. Gen Physiol Biophys 2018; 37:153-162. [PMID: 29593122 DOI: 10.4149/gpb_2017025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The slow force response (SFR) of a cardiac muscle to a sudden stretch is thought to be important in the regulatory adaptation of myocardial contraction. Autocrine-paracrine regulation pathways which involve angiotensin II are participating in this mechanism. On the other hand, renin-angiotensin-aldosterone system (RAS) is altered in hypertrophic or failing myocardium. We compared the effects of sudden stretch to SFR as well as to twitch and Ca2+ transient characteristics in rat myocardium with monocrotaline-induced heart failure with those in normal rat myocardium without and with inhibition of angiotensin II type-1 (AT1) receptors. Our findings indicate that the myocardium of rats with monocrotaline-induced right ventricular failure is deficient with activation of local RAS and therefore expresses blunted SFR, very similar to the depression of SFR observed in normal myocardium under inhibition of AT1 receptors. The "failing" myocardium does not further respond to the "putative" inhibition of AT1 receptors by losartan. In conclusion, SFR is related to autocrine-paracrine regulation of myocardial contraction in normal rat myocardium and that the involvement of RAS into stretch-induced modulation of contractility may be significantly altered in failing heart.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 620049 Yekaterinburg, Russian Federation.
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15
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Peyronnet R, Bollensdorff C, Capel RA, Rog-Zielinska EA, Woods CE, Charo DN, Lookin O, Fajardo G, Ho M, Quertermous T, Ashley EA, Kohl P. Load-dependent effects of apelin on murine cardiomyocytes. Prog Biophys Mol Biol 2017; 130:333-343. [PMID: 28935153 PMCID: PMC5726609 DOI: 10.1016/j.pbiomolbio.2017.09.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 01/26/2023]
Abstract
The apelin peptide is described as one of the most potent inotropic agents, produced endogenously in a wide range of cells, including cardiomyocytes. Despite positive effects on cardiac contractility in multicellular preparations, as well as indications of cardio-protective actions in several diseases, its effects and mechanisms of action at the cellular level are incompletely understood. Here, we report apelin effects on dynamic mechanical characteristics of single ventricular cardiomyocytes, isolated from mouse models (control, apelin-deficient [Apelin-KO], apelin-receptor KO mouse [APJ-KO]), and rat. Dynamic changes in maximal velocity of cell shortening and relaxation were monitored. In addition, more traditional indicators of inotropic effects, such as maximum shortening (in mechanically unloaded cells) or peak force development (in auxotonic contracting cells, preloaded using the carbon fibre technique) were studied. The key finding is that, using Apelin-KO cardiomyocytes exposed to different preloads with the 2-carbon fibre technique, we observe a lowering of the slope of the end-diastolic stress-length relation in response to 10 nM apelin, an effect that is preload-dependent. This suggests a positive lusitropic effect of apelin, which could explain earlier counter-intuitive findings on an apelin-induced increase in contractility occurring without matching rise in oxygen consumption.
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Affiliation(s)
- Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg · Bad Krozingen, Medical School of the University of Freiburg, Germany; Imperial College London, NHLI, Heart Science Centre, UK.
| | - Christian Bollensdorff
- Imperial College London, NHLI, Heart Science Centre, UK; Sidra Medical and Research Center, Qatar Foundation, Qatar
| | | | - Eva A Rog-Zielinska
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg · Bad Krozingen, Medical School of the University of Freiburg, Germany; Imperial College London, NHLI, Heart Science Centre, UK
| | - Christopher E Woods
- Stanford University Division of Cardiovascular Medicine, Stanford, USA; Palo Alto Medical Foundation, Burlingame, CA, USA
| | - David N Charo
- Stanford University Division of Cardiovascular Medicine, Stanford, USA
| | - Oleg Lookin
- Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russian Federation
| | - Giovanni Fajardo
- Stanford University Division of Cardiovascular Medicine, Stanford, USA
| | - Michael Ho
- Stanford University Division of Cardiovascular Medicine, Stanford, USA
| | | | - Euan A Ashley
- Stanford University Division of Cardiovascular Medicine, Stanford, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg · Bad Krozingen, Medical School of the University of Freiburg, Germany; Imperial College London, NHLI, Heart Science Centre, UK
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Lookin O, Balakin A, Kuznetsov D, Protsenko Y. The length-dependent activation of contraction is equally impaired in impuberal male and female rats in monocrotaline-induced right ventricular failure. Clin Exp Pharmacol Physiol 2015; 42:1198-206. [DOI: 10.1111/1440-1681.12471] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 07/23/2015] [Accepted: 07/27/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility; Institute of Immunology and Physiology; Ural Branch of Russian Academy of Sciences; Yekaterinburg Russian Federation
| | - Alexander Balakin
- Laboratory of Biological Motility; Institute of Immunology and Physiology; Ural Branch of Russian Academy of Sciences; Yekaterinburg Russian Federation
| | - Daniil Kuznetsov
- Laboratory of Biological Motility; Institute of Immunology and Physiology; Ural Branch of Russian Academy of Sciences; Yekaterinburg Russian Federation
| | - Yuri Protsenko
- Laboratory of Biological Motility; Institute of Immunology and Physiology; Ural Branch of Russian Academy of Sciences; Yekaterinburg Russian Federation
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17
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Lookin O, Kuznetsov D, Protsenko Y. Sex differences in stretch-dependent effects on tension and Ca(2+) transient of rat trabeculae in monocrotaline pulmonary hypertension. J Physiol Sci 2015; 65:89-98. [PMID: 25359385 PMCID: PMC10718032 DOI: 10.1007/s12576-014-0341-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [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: 05/21/2014] [Accepted: 10/03/2014] [Indexed: 10/24/2022]
Abstract
We aim to compare the effects of stretch on isometric tension/Ca(2+) transient in the right ventricular trabeculae of control (CONT) and hypertensive (MCT, monocrotaline application) adult male and female rats. The treatment with MCT resulted in RV hypertrophy in males only. Blunted active force-length relation and substantially prolonged twitch were found in MCT-males but not MCT-females (vs same-sex CONT). Ca(2+) transient was prolonged in both MCT-treated groups but extremely so in the MCT-males. The gradual stretch resulted in a distinct "bump" on Ca(2+) transient decline in CONT and MCT-treated groups. The integral magnitude of the "bump" was unaffected by the treatment with MCT in males or females but was larger in males vs females. The rate of "bump" development was significantly slower in MCT-males. In conclusion, the sex-specific differences in the stretch-dependent regulation of [Ca(2+)] i may underlie preservation of the Frank-Starling mechanism in female rat myocardium in monocrotaline-induced pulmonary hypertension.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, Yekaterinburg, 620049, Russia,
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18
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Katsnelson LB, Solovyova O, Balakin A, Lookin O, Konovalov P, Protsenko Y, Sulman T, Markhasin VS. Contribution of mechanical factors to arrhythmogenesis in calcium overloaded cardiomyocytes: model predictions and experiments. Prog Biophys Mol Biol 2011; 107:81-9. [PMID: 21699912 DOI: 10.1016/j.pbiomolbio.2011.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 06/06/2011] [Indexed: 10/18/2022]
Abstract
It is well-known that Ca²⁺ overload in cardiomyocytes may underlie arrhythmias. However, the possible contribution of mechanical factors to rhythm disturbances in Ca²⁺ overloaded myocytes has not been sufficiently investigated. We used a mathematical model of the electrical and mechanical activity of cardiomyocytes to reveal an essential role of the mechanisms of cardiac mechano-electric feedback in arrhythmogenesis in Ca²⁺ overloaded myocardium. In the model, the following mechanical factors increased Ca²⁺ overload in contracting cardiomyocytes and promoted rhythm disturbances: i) a decrease in the mechanical load for afterloaded contractions; and ii) a decrease in the initial length of sarcomeres for isometric twitches. In exact accordance with the model predictions, in experiments on papillary muscles from the right ventricle of guinea pigs with Ca²⁺ overloaded cardiomyocytes (using 0.5-1 μM of ouabain), we found that emergence of rhythm disturbances and extrasystoles depends on the mechanical conditions of muscle contraction.
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Affiliation(s)
- Leonid B Katsnelson
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences, 106 Pervomayskaya str, Ekaterinburg 620049, Russian Federation.
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Bollensdorff C, Lookin O, Kohl P. Assessment of contractility in intact ventricular cardiomyocytes using the dimensionless 'Frank-Starling Gain' index. Pflugers Arch 2011; 462:39-48. [PMID: 21494804 PMCID: PMC3114067 DOI: 10.1007/s00424-011-0964-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [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: 03/02/2011] [Revised: 03/28/2011] [Accepted: 03/28/2011] [Indexed: 11/29/2022]
Abstract
This paper briefly recapitulates the Frank–Starling law of the heart, reviews approaches to establishing diastolic and systolic force–length behaviour in intact isolated cardiomyocytes, and introduces a dimensionless index called ‘Frank–Starling Gain’, calculated as the ratio of slopes of end-systolic and end-diastolic force–length relations. The benefits and limitations of this index are illustrated on the example of regional differences in Guinea pig intact ventricular cardiomyocyte mechanics. Potential applicability of the Frank–Starling Gain for the comparison of cell contractility changes upon stretch will be discussed in the context of intra- and inter-individual variability of cardiomyocyte properties.
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Affiliation(s)
- Christian Bollensdorff
- Cardiac Biophysics and Systems Biology, The National Heart and Lung Institute, Imperial College, London, UK.
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Lookin O, Protsenko Y, Markhasin V. Slow Changes of Calcium Transient During Interaction of Inhomogeneous Cardiac Muscles. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1131] [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: 11/28/2022] Open
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Bollensdorff C, Lookin O, Helmes M, Kohl P. Length-Dependent Active Tension Development In Single Intact Cardiomyocytes, Isolated From Different Regions Of Guinea Pig Heart. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1937] [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: 11/29/2022] Open
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Smoluk L, Kobelev A, Lookin O, Balakin A, Protsenko Y. Contribution of intracellular structures into static and relaxation properties of papillary muscles. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.756.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Leonid Smoluk
- Institute of Immunology and PhysiologyUral Branch of Russian Academy of SciencesEkaterinburgRussian Federation
| | - Alexandr Kobelev
- Institute of Immunology and PhysiologyUral Branch of Russian Academy of SciencesEkaterinburgRussian Federation
| | - Oleg Lookin
- Institute of Immunology and PhysiologyUral Branch of Russian Academy of SciencesEkaterinburgRussian Federation
| | - Alexandr Balakin
- Institute of Immunology and PhysiologyUral Branch of Russian Academy of SciencesEkaterinburgRussian Federation
| | - Yuri Protsenko
- Institute of Immunology and PhysiologyUral Branch of Russian Academy of SciencesEkaterinburgRussian Federation
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Solovyova O, Katsnelson LB, Konovalov P, Lookin O, Moskvin AS, Protsenko YL, Vikulova N, Kohl P, Markhasin VS. Activation sequence as a key factor in spatio-temporal optimization of myocardial function. Philos Trans A Math Phys Eng Sci 2006; 364:1367-83. [PMID: 16766350 DOI: 10.1098/rsta.2006.1777] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Using one-dimensional models of myocardial tissue, implemented as chains of virtual ventricular muscle segments that are kinematically connected in series, we studied the role of the excitation sequence in spatio-temporal organization of cardiac function. Each model element was represented by a well-verified mathematical model of cardiac electro-mechanical activity. We found that homogeneous chains, consisting of identical elements, respond to non-simultaneous stimulation by generation of complex spatio-temporal heterogeneities in element deformation. These are accompanied by the establishment of marked gradients in local electro-mechanical properties of the elements (heterogeneity in action potential duration, Ca2+ transient characteristics and sarcoplasmic reticulum Ca2+ loading). In heterogeneous chains, composed of elements simulating fast and slow contracting cardiomyocytes from different transmural layers, we found that only activation sequences where stimulation of the slower elements preceded that of faster ones gave rise to optimization of the system's electro-mechanical function, which was confirmed experimentally. Based on the results obtained, we hypothesize that the sequence of activation of cardiomyocytes in different ventricular layers is one of the key factors of spatio-temporal organization of myocardium. Moreover, activation sequence and regional differences in intrinsic electro-mechanical properties of cardiac muscle must be matched in order to optimize myocardial function.
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Affiliation(s)
- O Solovyova
- Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Sciences (RAS) 91 Pervomayskaya Street, Ekaterinburg 620219, Russia.
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