Correlation of Contractile Force with a Calcium Pool in the Isolated Cat Heart

Bailey, Leslie E.; Dresel, Peter E.

doi:10.1085/jgp.52.6.969

Cited by 59 publications

(13 citation statements)

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“…The conclusions regarding the importance of muscle length in determining Ca2+ influx during the rate staircase are strengthened by the observation of a similar length effect on force staircase produced by an abrupt change in [Ca2+]e. Although the extent to which the change in transsarcolemmal Ca2+ flux that accompanies alterations in [Ca2+]e is electrogenic or electroneutral has not been determined, various kinetic components of Ca2+ flux have been demonstrated repeatedly to correlate with the kinetics of the Ca2+ staircase (Bailey & Dresel, 1968;Saari & Johnson, 1971Shine et al 1971;Langer et al 1974). Acceleration of the staircase at Lmax compared to the shorter length when [Ca2+]e is increased from 10 to 5 0 mM would suggest accelerated Ca2+ influx at Lmax, whereas identical force staircases at both lengths when [Ca2+]e is reduced from 5 0 to 1-0 mmt suggests no length difference in the kinetic component of Ca2+ efflux that has been associated with the force decline in similar experiments.…”

Section: Discussionmentioning

confidence: 99%

“…In the steady state, transsarcolemmal CaO+ flux associated with each beat cannot be characterized at present. However, when transsarcolemmal Ca2+ flux is altered, either by a change in the [Ca2+] in the bathing fluid (Bailey & Dresel, 1968;Saari & Johnson, 1971Shine, Serena & Langer, 1971;Langer, Serena & Nudd, 1974), or by a change in the rate of stimulation (Winegrad & Shanes, 1962;Grossman & Furchgott, 1964;Langer, 1965; Niedergerke, Page & Talbot, 1969), force production in each ensuing beat changes until a new steady level is achieved (Niedergerke, 1956;Chapman & Niedergerke, 1970;Chapman & Tunstall, 1971). The purpose of the present study is to determine whether muscle length modifies the kinetics of the force staircases that result from stimulation or from a change in the bathing fluid [Ca2+].…”

Section: Introductionmentioning

confidence: 99%

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Force staircase kinetics in mammalian cardiac muscle: modulation by muscle length

Lakatta

Spurgeon

1980

The Journal of Physiology

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SUMMARY1. Quiescent cat papillary muscles were stimulated to contract regularly at Lmax, the length at which force production is optimal, and at 0-85 Lm.x. The resulting increase in force production (rate staircase) at each length was characterized as an exponential function.2. When stimulated from quiescence at 24 min-' in a bathing fluid [Ca2+] of 2*5 mm, sixteen of twenty-three muscles exhibited biexponential increases in force production at both lengths. The coefficients of the exponential function at Lmax were 1*5-2 times greater than their counterparts at the shorter length, and this length difference was highly significant. When the force staircases were normalized to the peak developed force attained at each length, the number of beats to attain 25, 50, 75, and 98 % of peak force at 0*85 Lmax was approximately twice that required at Lmax.3. At a given length the force staircase (1) exhibited a dependency on the number of beats rather than on stimulation frequency over a range of 12-60 min-, (2) was accelerated by increasing the bathing fluid [Ca2+] from 1x0 to 5 0 mm, (3) was accelerated in the presence of isoproterenol, and (4) was retarded in the presence of DLverapamil. Over the entire range of bathing fluid [Ca2+] and at all stimulation frequencies 24 min-' and above, more beats were required to complete a given level of the normalized staircase at 0*85 Lmax than at Lmax. There was no length difference in the presence of verapamil. These data suggest that transsarcolemmal Ca2+ influx is an important determinant of the kinetics of the force staircase, and the length dependence of the latter indicates that muscle length is an important determinant of transsarcolemmal Ca2+ influx.4. This conclusion was strengthened by the results of additional studies in which the [Ca2+] of the bathing fluid was abruptly increased from 1i0 to 5-0 mm with the muscle beating in the steady state. The resulting increase in force production (Ca2+ staircase) was described by a monoexponential function with a greater coefficient at Lmax than 0-85 Lmax; when normalized to the peak force difference in the two [Ca2+] at each length, a given level of the staircase was achieved in significantly fewer beats at Lmax than at the shorter length.5. The data provide a mechanism which, in part, explains the length dependence of excitation-contraction coupling in cardiac muscle with intact sarcolemmae.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Force staircase kinetics in mammalian cardiac muscle: modulation by muscle length

Lakatta

Spurgeon

1980

The Journal of Physiology

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“…The exchangeability of calcium contained in the heart muscle has been analyzed either by isotopic method (DECARO, 1967;SHINE et al, 1971) or by perfusion of the heart with calcium-free solution (BAILEY and DRESEL, 1968;SAARI and JOHNSON, 1971). In the present experiment this was determined by the use of the latter method on the toad, guinea pig, and rat heart preparations previously equilibrated with a normal solution.…”

Section: Calcium Washout Experimentsmentioning

confidence: 99%

Difference in Calcium Content of Atrial and Ventricular Muscle

Fukuda

1975

Jpn.J.Physiol

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The calcium content and inulin space of the atrial and ventricular muscle were determined in isolated perfused heart of the toad, bullfrog, guinea pig, rat, and cat. In all species studied, the total and "cellular" calcium content of the atrium were higher than those of the ventricle. A high calcium content of the atrial muscle was also observed in fresh unperfused hearts. The total calcium content of atrial and ventricular muscles increased when extracellular phosphate concentration was increased. When severe ventricular arrhythmia such as fibrillation occurred during perfusion, the total calcium content of the ventricle increased. The decay of tissue calcium content with calcium washout was examined in the toad, guinea pig, and rat heart. It was revealed that about 80 percent of total calcium existed as "exchangeable" calcium in both atrial and ventricular muscles. When the extracellular calcium concentration ([Ca]0) was altered in the toad, guinea pig, and rat heart preparation, the cellular calcium content of atrial muscle varied in proportion to [Ca])0 whereas that of ventricular muscle remained fairly constant at a higher [Ca]0 value. The development of contractile tension in the atrial and ventricular muscles at various [Ca]0 values corresponded well to these changes in the cellular calcium content except for the rat ventricle in which the contractile tension was almost proportional to [Ca]0. The relationship between the development of contractile tension and the level of cellular calcium content or [Ca]0 was discussed.

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“…The results of the Na + ,K + -ATPase measurements provide evidence that the net caldum gain of the cells after caldum repletion may be associated, in part, with a loss in ability of the sarcolemma to remove caldum from the cytosol. (Circ Res 54: 217-226, 1984) WHEN isolated hearts are perfused with a Ca ++ -free medium, the contractile activity declines quickly (Ringer, 1883;Bailey and Dresel, 1968;Crevey et al, 1978). The reintroduction of Ca ++ results in a massive release of enzymes and other proteins from the heart, a loss of tissue high energy phosphates, development of contracture, swelling of mitochondria, formation of intramitochondrial electron-dense material, and severe ultrastructural damage (Zimmerman and Hulsmann, 1966;Zimmerman et al, 1967;Ruigrok et al, 1975;Yates and Dhalla, 1975;Alto and Dhalla, 1979;Grinwald and Nayler, 1981;Rich and Langer, 1982).…”

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confidence: 99%

Biochemical properties of membranes isolated from calcium-depleted rabbit hearts.

Lamers¹,

Stinis²,

Ruigrok³

1984

Circulation Research

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SUMMARY. The purpose of this study was to define the biochemical properties of sarcolemma from the caldum-depleted rabbit heart. Caldum repletion after caldum-free perfusion results in irreversible damage to the heart (caldum paradox). No difference was found in specific activity of the Na + -Ca ++ antiporter in a crude preparation of sarcolemmal vesicles that was isolated from caldum-depleted hearts, compared with control perfused hearts. Likewise, the passive caldum efflux from sarcolemmal vesicles, preloaded with caldum via the Na + -Ca ++ antiporter, showed rates that were identical with control values. This indicates that the sarcolemma caldum permeability is not affected by caldum-free perfusion of the heart. Na + ,K + -ATPase activity in sarcolemma isolated from caldum-depleted hearts was reduced by 75% (P < 0.005) compared with the control activity. Sarcolemmal phosphoproteins, whether produced by endogenous cyclic AMP-or caldum-calmodulin-dependent protein kinase, were not altered by caldum-free perfusion of the heart. The content of an important caldum-binding site in the myocardial cell, the sialic add residues, was also estimated. Only a long period (60 minutes) of caldum-free perfusion resulted in a significant decrease (by 68%, P < 0.025) of sialic add content in the homogenate but not in the sarcolemma preparation. In hearts that were reperfused for 15 minutes with a normal caldum concentration (1.3 mM), sarcolemmal Na + ,K + -ATPase remained depressed and caldum permeability was still unchanged. It is possible that the sarcolemma isolation method selected a distinct part of the sarcolemma from the caldum-depleted and repleted heart that had no modified glycocalyx and permeability barriers to caldum ions, and that another part of the sarcolemma with altered properties was lost during the isolation procedure. Another possibility is that reconstitution processes during isolation affected membrane permeability properties. The results of the Na + ,K + -ATPase measurements provide evidence that the net caldum gain of the cells after caldum repletion may be associated, in part, with a loss in ability of the sarcolemma to remove caldum from the cytosol. (Circ Res 54: 217-226, 1984)

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Correlation of Contractile Force with a Calcium Pool in the Isolated Cat Heart

Abstract: The relationship between cellular calcium (Ca) stores and isometric contractile force was investigated in isolatcd, gas-pcrfuscd cat hearts.

Cited by 59 publications

References 9 publications

Force staircase kinetics in mammalian cardiac muscle: modulation by muscle length

Force staircase kinetics in mammalian cardiac muscle: modulation by muscle length

Difference in Calcium Content of Atrial and Ventricular Muscle

Biochemical properties of membranes isolated from calcium-depleted rabbit hearts.

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