Effect of transient stretch on intracellular Ca2+ during triggered propagated contractions in intact trabeculae

2001 ◽  
Vol 79 (1) ◽  
pp. 68-72 ◽  
Author(s):  
Masahito Miura ◽  
Yuji Wakayama ◽  
Yoshinao Sugai ◽  
Yutaka Kagaya ◽  
Jun Watanabe ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Muscle Length ◽  
Twitch Contraction ◽  
Quick Release ◽  
Rat Hearts ◽  
Force Peak ◽  
Intracellular Ca ◽  
The Moment ◽  
The Right ◽  
Electrical Stimuli

Transient stretch of cardiac muscle during a twitch contraction may dissociate Ca2+ from myofilaments into the cytosol at the moment of quick release of the muscle. We studied the effect of stretch and quick release of trabeculae on changes in intracellular Ca2+ ([Ca2+]i) during triggered propagated contractions (TPCs). Trabeculae were dissected from the right ventricle of 9 rat hearts. [Ca2+]i was measured using electrophoretically injected fura-2. Force was measured using a silicon strain gauge and sarcomere length was measured using laser diffraction techniques. Reproducible TPCs (n = 13) were induced by trains of electrical stimuli (378 ± 19 ms interval) for 7.5 s at [Ca2+]o of 2.0 mM (27.9 ± 0.2°C). The latency of the TPC force and the underlying increase in [Ca2+]i was calculated from the time (TimeF) between the last stimulus and the peak of TPC force (PeakF), or the time (TimeCa) between the last stimulus and the peak of the increase in [Ca2+]i during the TPCs (PeakCa). As a result of a 10% increase in muscle length for 150-200 ms during the last stimulated twitches, TimeF and TimeCa decreased and PeakF and PeakCa increased significantly (n = 13). In addition, transient stretch sometimes induced a twitch contraction subsequent to the accelerated TPC and its underlying increase in [Ca2+]i. These results suggest that Ca2+ binding and dissociation from the myofilaments by the stretch and quick release of muscle may modulate the TPC force and the underlying increases in [Ca2+]i and play an important role in the induction of arrhythmias.Key words: rat cardiac trabeculae, stretch, calcium transients.

scholarly journals Stretch and quick release of rat cardiac trabeculae accelerates Ca2+ waves and triggered propagated contractions

2001 ◽  
Vol 281 (5) ◽  
pp. H2133-H2142 ◽  
Author(s):  
Yuji Wakayama ◽  
Masahito Miura ◽  
Yoshinao Sugai ◽  
Yutaka Kagaya ◽  
Jun Watanabe ◽  
...  
Keyword(s):  
Strain Gauge ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Laser Diffraction ◽  
Active Force ◽  
Quick Release ◽  
Rat Hearts ◽  
Initiation And Propagation ◽  
Intracellular Ca ◽  
Ventricular Trabeculae

Rapid shortening of active cardiac muscle [quick release (QR)] dissociates Ca2+ from myofilaments. We studied, using muscle stretches and QR, whether Ca2+ dissociation affects triggered propagated contractions (TPCs) and Ca2+waves. The intracellular Ca2+ concentration was measured by a SIT camera in right ventricular trabeculae dissected from rat hearts loaded with fura 2 salt, force was measured by a silicon strain gauge, and sarcomere length was measured by laser diffraction while a servomotor controlled muscle length. TPCs ( n = 27) were induced at 28°C by stimulus trains (7.5 s at 2.65 ± 0.13 Hz) at an extracellular Ca2+ concentration ([Ca2+]o) = 2.0 mM or with 10 μM Gd3+ at [Ca2+]o = 5.2 ± 0.73 mM. QR during twitch relaxation after a 10% stretch for 100–200 ms reduced both the time between the last stimulus and the peak TPC (PeakTPC) and the time between the last stimulus and peak Ca2+ wave (PeakCW) and increased PeakTPC and PeakCW ( n= 13) as well as the propagation velocity ( V prop; n = 8). Active force during stretch also increased V prop( r = 0.84, n = 12, P < 0.01), but Gd3+ had no effect ( n = 5). These results suggest that Ca2+ dissociation by QR during relaxation accelerates the initiation and propagation of Ca2+ waves.

Effects of acidosis on Ca2+sensitivity of contractile elements in intact ferret myocardium

1998 ◽  
Vol 274 (1) ◽  
pp. H147-H154 ◽  
Author(s):  
Kimiaki Komukai ◽  
Tetsuya Ishikawa ◽  
Satoshi Kurihara
Keyword(s):  
Muscle Length ◽  
Length Change ◽  
Troponin C ◽  
Tetanic Contraction ◽  
Twitch Contraction ◽  
Intracellular Ca ◽  
The Right ◽  
The Hill ◽  
The Relationship ◽  
Stimulation Of

We investigated the effects of acidosis on the intracellular Ca2+ concentration ([Ca2+]i) and contractile properties of intact mammalian cardiac muscle during tetanic and twitch contractions. Aequorin was injected into ferret papillary muscles, and the [Ca2+]iand tension were simultaneously measured. Acidosis was attained by increasing the CO2 concentration in the bicarbonate (20 mM)-buffered Tyrode solution from 5% (pH 7.35, control) to 15% (pH 6.89, acidosis). Tetanic contraction was produced by repetitive stimulation of the preparation following treatment with 5 μM ryanodine. The relationship between [Ca2+]iand tension was measured 6 s after the onset of the stimulation and was fitted using the Hill equation. Acidosis decreased the maximal tension to 81 ± 2% of the control and shifted the [Ca2+]i-tension relationship to the right by 0.18 ± 0.01 pCa units. During twitch contraction, a quick shortening of muscle length from the length at which developed tension became maximal ( L max) to 92% L maxproduced a transient change in the [Ca2+]i(extra Ca2+). The magnitude of the extra Ca2+ was dependent on the [Ca2+]iimmediately before the length change, suggesting that the extra Ca2+ is related to the amount of troponin-Ca complex. Acidosis decreased the normalized extra Ca2+ to [Ca2+]iimmediately before the length change, which indicates that the amount of Ca2+ bound to troponin C is less when [Ca2+]iis the same as in the control. The decrease in the Ca2+ binding to troponin C explains the decrease in tetanic and twitch contraction, and mechanical stress applied to the preparation induced less [Ca2+]ichange in acidosis.

scholarly journals Acute effects of gastrocnemius muscle stretching after contusion in rats

2014 ◽  
Vol 21 (1) ◽  
pp. 53-59
Author(s):  
Ana Carolina Brandt de Macedo ◽  
Julye Leiko Ywazaki ◽  
Jaqueline Pacheco ◽  
Sibelly Gonçalves ◽  
Anna Raquel Silveira Gomes
Keyword(s):  
Body Weight ◽  
Sarcomere Length ◽  
Body Weight Gain ◽  
Muscle Length ◽  
Acute Effects ◽  
Muscle Weight ◽  
Final Body Weight ◽  
Male Wistar Rats ◽  
The Right ◽  
Sarcomere Number

The aim of this study was to evaluate the acute effects of stretching after gastrocnemius contusion in rats. Thirty-three male Wistar rats were selected (8 weeks, 219±35 g) and divided into 4 groups: Control (CG, n=3) - intact; Lesion (LG, n=10); Stretching (SG, n=10): Lesion and Stretching (LSG, n=10). The right gastrocnemius (RG) was submitted to contusion. Stretching on RG was performed manually, with 4 repetitions of 30 seconds each day, for 5 consecutive days, beginning 72 hour after contusion. One week later, rats were weighed and both paws were removed for investigation of muscle length, serial sarcomere number and sarcomere length. The final body weight increased in all groups. The muscle weight and length, as well as the serial sarcomere number (SSN) of LG, were higher than SG. However, the SSN of LSG was higher than SG. The sarcomere length of SG was the highest among all groups. It was concluded that the contusion and stretching did not affect body weight gain. The stretching induced sarcomerogenesis in injured muscle, but did not modify the healthy muscle.

Sarcomere length and capillary curvature of rat hindlimb muscles in vivo

1995 ◽  
Vol 78 (6) ◽  
pp. 2047-2051 ◽  
Author(s):  
M. A. Ledvina ◽  
S. S. Segal
Keyword(s):  
Skeletal Muscle ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Physiological Saline ◽  
Mammalian Skeletal Muscle ◽  
Sprague Dawley ◽  
Hindlimb Muscles ◽  
Physiological Saline Solution ◽  
The Right

Mammalian skeletal muscle fibers have been reported to develop maximum force at a sarcomere length (Ls) of approximately 2.5 microns. However, the functional range of muscle length (Lm) and Ls encountered by skeletal muscle in vivo is not well defined. Changes in Ls markedly influence capillary geometry, but this effect has been shown only in fixed preparations. The purpose of this study was to evaluate the influence of limb position on Lm, Ls, and capillary geometry in living undisturbed hindlimb muscles. We tested the hypothesis that maximal excursion of the foot would have similar effects on Ls and capillary geometry of antagonistic soleus (Sol) and extensor digitorum longus (EDL) muscles in vivo. Female Sprague-Dawley rats (n = 9; 243 +/- 3 g) were anesthetized (pentobarbital sodium; 35 mg/kg). The right Sol and EDL muscles were exposed and irrigated with physiological saline solution (34 degrees C; pH 7.4). Sarcomeres and capillaries were observed with video microscopy (total magnification x 1,900; spatial resolution < 1 micron); sarcomeres were labeled with a fluorescent dye [4-(4-diethylaminostyryl)-N-methylpyridinium iodide]. As foot angle increased from 30 degrees (maximal dorsiflexion) to 170 degrees (maximal plantarflexion), Lm and Ls increased for EDL muscles (27.51 +/- 0.42 to 30.97 +/- 0.25 mm and 2.33 +/- 0.01 to 3.09 +/- 0.05 microns, respectively; P < 0.05) and decreased for Sol muscles (26.09 +/- 0.38 to 20.27 +/- 0.34 mm and 3.17 +/- 0.03 to 2.22 +/- 0.04 microns, respectively; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological Basis of the Disparity Between Muscle Length and Sarcomere Length in the Myocardium

1973 ◽  
Vol 31 ◽  
pp. 422-423
Author(s):  
G.E. Adomian ◽  
L. Chuck ◽  
W.W. Pannley
Keyword(s):  
Cardiac Muscle ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Contractile Force ◽  
Direct Function ◽  
Morphological Basis ◽  
Tension Curve

Sonnenblick, et al, have shown that sarcomeres change length as a function of cardiac muscle length along the ascending portion of the length-tension curve. This allows the contractile force to be expressed as a direct function of sarcomere length. Below L max, muscle length is directly related to sarcomere length at lengths greater than 85% of optimum. However, beyond the apex of the tension-length curve, i.e. L max, a disparity occurs between cardiac muscle length and sarcomere length. To account for this disproportionate increase in muscle length as sarcomere length remains relatively stable, the concept of fiber slippage was suggested as a plausible explanation. These observations have subsequently been extended to the intact ventricle.

Would you Make the Right Decision? – Decision Making Biases in Economy - Related Dilemmas

2018 ◽  
Vol 9 (1) ◽  
pp. 59-66
Author(s):  
Zsuzsanna Gödör ◽  
Georgina Szabó
Keyword(s):  
Decision Making ◽  
Online Survey ◽  
Framing Effect ◽  
Economic Knowledge ◽  
Bank Account ◽  
Financial Decisions ◽  
Hungarian Population ◽  
The Moment ◽  
The Right ◽  
Decision Making Biases

Abstract As they say, money can’t buy happiness. However, the lack of it can make people’s lives much harder. From the moment we open our first bank account, we have to make lots of financial decisions in our life. Should I save some money or should I spend it? Is it a good idea to ask for a loan? How to invest my money? When we make such decisions, unfortunately we sometimes make mistakes, too. In this study, we selected seven common decision making biases - anchoring and adjustment, overconfidence, high optimism, the law of small numbers, framing effect, disposition effect and gambler’s fallacy – and tested them on the Hungarian population via an online survey. In the focus of our study was the question whether the presence of economic knowledge helps people make better decisions? The decision making biases found in literature mostly appeared in the sample as well. It proves that people do apply them when making decisions and in certain cases this could result in serious and costly errors. That’s why it would be absolutely important for people to learn about them, thus increasing their awareness and attention when making decisions. Furthermore, in our research we did find some connection between decisions and the knowledge of economics, people with some knowledge of economics opted for the better solution in bigger proportion

JUSTICE AND SOCIAL CHANGE FOR INCLUSIVE EDUCATION IN INDONESIA AND ASEAN FOR DISABLED PERSONS (STUDY ON PEOPLE AFFECTED BY LEPROSY)

2017 ◽  
Vol 1 (1) ◽  
pp. 1-5
Author(s):  
Nuah Perdamenta Tarigan ◽  
Christian Siregar ◽  
Simon Mangatur Tampubolon
Keyword(s):  
Inclusive Education ◽  
Local Governments ◽  
Disabled Persons ◽  
Equal Rights ◽  
Central Java ◽  
The People ◽  
Asean Countries ◽  
The Government ◽  
The Moment ◽  
The Right

Justice that has not existed and is apparent among the disabilities in Indonesia is very large and spread in the archipelago is very large, making the issue of equality is a very important thing especially with the publication of the Disability Act No. 8 of 2016 at the beginning of that year. Only a few provinces that understand properly and well on open and potential issues and issues will affect other areas including the increasingly growing number of elderly people in Indonesia due to the increasing welfare of the people. The government of DKI Jakarta, including the most concerned with disability, from the beginning has set a bold step to defend things related to disability, including local governments in Solo, Bali, Makassar and several other areas. Leprosy belonging to the disability community has a very tough marginalization, the disability that arises from leprosy quite a lot, reaches ten percent more and covers the poor areas of Indonesia, such as Nusa Tenggara Timur, Papua, South Sulawesi Provinces and even East Java and West Java and Central Java Provinces. If we compare again with the ASEAN countries we also do not miss the moment in ratifying the CRPD (Convention of Rights for People with Disability) into the Law of Disability No. 8 of 2016 which, although already published but still get rejections in some sections because do not provide proper empowerment and rights equality. The struggle is long and must be continued to build equal rights in all areas, not only health and welfare but also in the right of the right to receive continuous inclusive education.

(-)-Terpinen-4-ol changes intracellular Ca 2+ handling and induces pacing disturbance in rat hearts

2017 ◽  
Vol 807 ◽  
pp. 56-63 ◽  
Author(s):  
Antonio Nei Santana Gondim ◽  
Aline Lara ◽  
Artur Santos-Miranda ◽  
Danilo Roman-Campos ◽  
Sandra Lauton-Santos ◽  
...  
Keyword(s):  
Rat Hearts ◽  
Intracellular Ca

scholarly journals Attenuation of extracellular ATP response in cardiomyocytes isolated from hearts subjected to ischemia-reperfusion

2005 ◽  
Vol 289 (2) ◽  
pp. H614-H623 ◽  
Author(s):  
Harjot K. Saini ◽  
Vijayan Elimban ◽  
Naranjan S. Dhalla
Keyword(s):  
Cardiac Function ◽  
Positive Inotropic Effect ◽  
Ischemia Reperfusion ◽  
Cardiac Contractility ◽  
Extracellular Atp ◽  
Binding Characteristics ◽  
Rat Hearts ◽  
The Status ◽  
Intracellular Ca ◽  
Isolated Rat

Extracellular ATP is known to augment cardiac contractility by increasing intracellular Ca2+ concentration ([Ca2+]i) in cardiomyocytes; however, the status of ATP-mediated Ca2+ mobilization in hearts undergoing ischemia-reperfusion (I/R) has not been examined previously. In this study, therefore, isolated rat hearts were subjected to 10–30 min of global ischemia and 30 min of reperfusion, and the effect of extracellular ATP on [Ca2+]i was measured in purified cardiomyocytes by fura-2 microfluorometry. Reperfusion for 30 min of 20-min ischemic hearts, unlike 10-min ischemic hearts, revealed a partial depression in cardiac function and ATP-induced increase in [Ca2+]i; no changes in basal [Ca2+]i were evident in 10- or 20-min I/R preparations. On the other hand, reperfusion of 30-min ischemic hearts for 5, 15, or 30 min showed a marked depression in both cardiac function and ATP-induced increase in [Ca2+]i and a dramatic increase in basal [Ca2+]i. The positive inotropic effect of extracellular ATP was attenuated, and the maximal binding characteristics of 35S-labeled adenosine 5′-[γ-thio]triphosphate with crude membranes from hearts undergoing I/R was decreased. ATP-induced increase in [Ca2+]i in cardiomyocytes was depressed by verapamil and Cibacron Blue in both control and I/R hearts; however, this response in I/R hearts, unlike control hearts, was not affected by ryanodine. I/R-induced alterations in cardiac function and ATP-induced increase in [Ca2+]i were attenuated by treatment with an antioxidant mixture and by ischemic preconditioning. The observed changes due to I/R were simulated in hearts perfused with H2O2. The results suggest an impairment of extracellular ATP-induced Ca2+ mobilization in I/R hearts, and this defect appears to be mediated through oxidative stress.

Abstract 5402: Two Photon Microscopy Measurements Of Sub-epicardial Sarcomere Length In Perfused Rat Hearts

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Patrizia Camelliti ◽  
Gil Bub ◽  
Daniel J Stuckey ◽  
Christian Bollensdorff ◽  
Damian J Tyler ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Left Ventricular ◽  
Model Systems ◽  
Future Research ◽  
Fundamental Parameter ◽  
Rat Hearts ◽  
Perfused Hearts ◽  
Over Time

Sarcomere length (SL) is a fundamental parameter underlying the Frank Starling relation in the heart, as it offers an absolute representation of myocardial stretch. Previous studies addressed the Frank Starling relation by measuring SL in isolated myocytes or muscle strips. Here, we report first data obtained using a novel technique to measure sub-epicardial SL in perfused hearts. Rat hearts were Langendorff perfused (normal Tyrode solution) at a constant pressure of 90mmHg, labeled with the fluorescent membrane marker di-4-ANEPPS, and then arrested with high-K + Tyrode for either 2-photon microscopy (n=4) or MRI (n=4). Image analysis software was developed to extract SL at the cell level from >1,400 2-photon images (Fig 1 ) and correct for cell angle. SL increased by 10±2 % between 30 and 80 min of perfusion (1.98±0.04 to 2.17±0.03 μm; p<0.05; Fig 1 ). Measurements of left ventricular myocardial volume (LVMV) were made in vivo and in perfused hearts using 3D MRI. LVMV increased by 24±7% from in vivo to 30 min of perfusion, and by 11±3 % between 30 and 90 min (539±35; 664±44; 737±49 mm 3 , respectively; p<0.05; Fig 1 ). We show that SL can be measured in isolated perfused hearts. The method allowed monitoring of changes in SL over time, and showed that SL and LVMV increase to a similar extent during 30–80 min perfusion with crystalloid solution, probably due to tissue oedema. This result, together with the increase in LVMV during the first 30 min, highlights the pronounced differences between in vivo , in situ , and in vitro model systems for studies of cardiac physiology and mechanics. Future research will compare changes in SL in healthy hearts and disease models involving contractile dysfunction. Figure 1: Left: 2-photon microscopy image of di-4-ANEPPS labeled myocardium. Right: SL and LVMV changes over time.

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