Direct control of contraction force of single frog atrial cells by extracellular ions

Shepherd, Neal; Kavaler, Frederic

doi:10.1152/ajpcell.1986.251.5.c653

Cited by 24 publications

(18 citation statements)

References 16 publications

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“…The frequency bandwidth and noise level (RMS) in our measurements were comparable to those of the other transducer methods [5,8,10,12,16,20]. Our transducer thus achieves better isometric conditions and a better frequency response.…”

Section: Discussionsupporting

confidence: 71%

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Knobloch

Vögel

Fink

2000

Pflügers Arch - Eur J Physiol

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A new transducer, using the effect of frustrated total internal reflection of electromagnetic waves, was developed for displacement and force measurements in muscle research. The physical theory for this effect predicts the formation of an evanescent electromagnetic field in the gap between two separated optical surfaces. This evanescent electromagnetic field enables the transmission of light across the gap between the two media, an effect not contained in ray optics formalism. In the apparatus described here, the optical surfaces were obtained by bevelling 2 optical fibres to angles higher than the specific critical angle of the media used. Since the amount of transmitted light depends strongly on the distance between the surfaces, very small forces are detectable if one fibre is used as a cantilever. To test the transducer a small myofibrillar bundle (20 microm diameter) was mounted isometrically on it and contraction activated by release of "caged" Ca2+. Force and displacement steps of 180-220 nN and 9-11 nm respectively were measured with resolutions of 10 nN and 288 pm, respectively. From theoretical and practical considerations, it is expected that the presented principle will be able to achieve even much higher sensitivity for the determination of force (better than picoNewton) and distance (femtometre).

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Section: Discussionsupporting

confidence: 71%

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Knobloch

Vögel

Fink

2000

Pflügers Arch - Eur J Physiol

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“…In 1986, Shepherd et al mounted single bullfrog atrial myocytes to a pair of glass rods of known compliance [3]. The contractile force was calculated by means of optical displacement recording of the glass rods.…”

Section: Introductionmentioning

confidence: 99%

Mechano-Pharmacological Characterization of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells

Goßmann

Frotscher

Linder³

et al. 2016

Cell Physiol Biochem

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Background/Aims: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. Methods: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca²⁺ channels (S-Bay K8644/verapamil) and Na⁺ channels (veratridine/lidocaine). Results: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. Conclusion: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.

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“…It is thought that depolarization of surface membrane activates the Ca24 current (Ic. ) Studies with light-sensitive Ca2"-channel blockers (5), antipyrylazo III as an extracellular Ca24 probe (6), or rapid exchange of solutions in isolated single myocytes (7) suggest that the transsarcolemmal Ca24 influx is the primary source for the activation of tension in the frog heart. Similar studies on the mammalian heart, however, show that ICa contributes at best between 5 and 30o to the activation of contraction, depending on experimental conditions (8).…”

mentioning

confidence: 99%

Epinephrine enhances Ca2+ current-regulated Ca2+ release and Ca2+ reuptake in rat ventricular myocytes.

Callewaert

Cleemann

Morad

1988

Proc. Natl. Acad. Sci. U.S.A.

125

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The voltage dependence of the intracellular Ca2 + transients was measured in single rat ventricular myocytes with the fluorescent Ca24 indicator dye fura-2. The whole-cell voltage damp technique was used to measure the membrane current, and 0.9 mM fura-2 was loaded into the cell by including it in the dialyzing solution of the patch electrode. A mechanical light chopper operating at 1200 Hz was used to obtain simultaneous measurements of the intracellular Ca2+ activity with fluorescence excitation on either side of the isosbestic point (330 am and 410 nm). The symmetry of the two optical Ca24 signals was used as a criterion to guard against artifacts resulting, for instance, from motion. The voltage dependence of peak Ca2+ current and the Ca24 transient measured 25 ms after depolarizing clamps from a holding potential of -40 mV were bell-shaped and virtually identical. The Ca2+ entry estimated from the integral of the Ca2+ current (0 mV, 25 ms) corresponds to a 5-10 pM increase in the total intracellular Ca24 concentration, whereas the optical signal indicated a 100 FM increase in total intracellular Ca24. Repolarization of clamp pulses from highly positive potentials were accompanied by a second Ca2+ transient, the magnitude of which, when summed with that measured during depolarization, was nearly constant. Ryanodine (10 #M) had little or no effect on the peak Ca2+ current but reduced the magnitude of the early Ca2+ transients by 70-90%. Epinephrine (1 FM) increased the Ca2+ current and the Ca2+ transients, accelerated the rate of decline of the Ca2+ transients at potentials between -30 and + 70 mV, and reduced the intracellular [Ca2+] below baseline at potentials positive to + 80 or negative to -40 mV, where clamp pulses did not elicit any Ca2+ release. Elevation of intracellular cAMP mimicked the relaxant effect of epinephrine at depolarizing potentials, whereas elevation of extracellular [Ca2+] did not. These results suggest that most of the activator Ca2+ in rat ventricular cells is released from the sarcoplasmic reticulum as a graded response to sarcolemmal Ca2+ influx. Consistent with a graded Ca2+-induced Ca2+ release we find that epinephrine increases the internal Ca2+ release by increasing the Ca2+ current. Epinephrine may also increase the Ca2+ content of the sarcoplasmic reticulum that may, in turn,

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Direct control of contraction force of single frog atrial cells by extracellular ions

Cited by 24 publications

References 16 publications

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

A new transducer based on the evanescent field effect for high-resolution displacement and force measurements

Mechano-Pharmacological Characterization of Cardiomyocytes Derived from Human Induced Pluripotent Stem Cells

Epinephrine enhances Ca2+ current-regulated Ca2+ release and Ca2+ reuptake in rat ventricular myocytes.

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