Contractile force measured in unskinned isolated adult rat heart fibres

Brady, A. J.; Tan, S. T.; Ricchiuti, N. V.

doi:10.1038/282728a0

Cited by 66 publications

(36 citation statements)

References 6 publications

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“…All of the functional characteristics described were analogous to those established by a number of studies using papillary muscle (4,6) or trabeculae preparations (7). The present results confirmed the fact that each myocyte forms the functional basis for ventricular function and that single cell mechanics can be a link between subcellular events and ventricular mechanics.…”

Section: Discussionsupporting

confidence: 86%

Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions

Nishimura¹,

Yasuda²,

Katoh³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

101

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One of the most salient characteristics of the heart is its ability to adjust work output to external load. To examine whether a single cardiomyocyte preparation retains this property, we measured the contractile function of a single rat cardiomyocyte under a wide range of loading conditions using a force-length measurement system implemented with adaptive control. A pair of carbon fibers was used to clamp the cardiomyocyte, attached to each end under a microscope. One fiber was stiff, serving as a mechanical anchor, while the bending motion of the compliant fiber was monitored for force-length measurement. Furthermore, by controlling the position of the compliant fiber using a piezoelectric translator based on adaptive control, we could change load dynamically during contractions. Under unloaded conditions, maximal shortening velocity was 106 +/- 8.9 microm/s (n = 13 cells), and, under isometric conditions, peak developed force reached 5,720 nN (41.6 +/- 5.6 mN/mm(2); n = 17 cells). When we simulated physiological working conditions consisting of an isometric contraction, followed by shortening and relaxation, the average work output was 828 +/- 123 J/m(3) (n = 20 cells). The top left corners of tension-length loops obtained under all of these conditions approximate a line, analogous to the end-systolic pressure-volume relation of the ventricle. All of the functional characteristics described were analogous to those established by studies using papillary muscle or trabeculae preparations. In conclusion, the present results confirmed the fact that each myocyte forms the functional basis for ventricular function and that single cell mechanics can be a link between subcellular events and ventricular mechanics.

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Section: Discussionsupporting

confidence: 86%

Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions

Nishimura¹,

Yasuda²,

Katoh³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

101

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“…Cultures of dissociated embryonic or neonatal cardiac myocytes, respectively, have been used in studies on the pharmacology of cardiovascular physiology for more than 50 years [2]. Various approaches were made using these cells as models to investigate myocyte-related characteristics such as ion channel function [3,4], cardiac hypertrophy [5] and the contractility of cardiac structures [6][7][8][9]. The patch-clamp technique [10] became a wellaccepted tool for analysing electrical properties such as action potentials of isolated cardiac myocytes.…”

Section: Introductionmentioning

confidence: 99%

Contractile tension and beating rates of self-exciting monolayers and 3D-tissue constructs of neonatal rat cardiomyocytes

Linder

Trzewik

Rüffer

et al. 2009

Med Biol Eng Comput

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The CellDrum technology (The term 'CellDrum technology' includes a couple of slightly different technological setups for measuring lateral mechanical tension in various types of cell monolayers or 3D-tissue constructs) was designed to quantify the contraction rate and mechanical tension of self-exciting cardiac myocytes. Cells were grown either within flexible, circular collagen gels or as monolayer on top of respective 1-mum thin silicone membranes. Membrane and cells were bulged outwards by air pressure. This biaxial strain distribution is rather similar the beating, blood-filled heart. The setup allowed presetting the mechanical residual stress level externally by adjusting the centre deflection, thus, mimicking hypertension in vitro. Tension was measured as oscillating differential pressure change between chamber and environment. A 0.5-mm thick collagen-cardiac myocyte tissue construct induced after 2 days of culturing (initial cell density 2 x 10(4) cells/ml), a mechanical tension of 1.62 +/- 0.17 microN/mm(2). Mechanical load is an important growth regulator in the developing heart, and the orientation and alignment of cardiomyocytes is stress sensitive. Therefore, it was necessary to develop the CellDrum technology with its biaxial stress-strain distribution and defined mechanical boundary conditions. Cells were exposed to strain in two directions, radially and circumferentially, which is similar to biaxial loading in real heart tissues. Thus, from a biomechanical point of view, the system is preferable to previous setups based on uniaxial stretching.

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“…Several techniques have been devised for directly measuring tension changes in small, isolated cell preparations (Brady et al ., 1979 ;Tarr et al, 1979 ;Warshaw and Fay, 1983) . However, there are several practical limitations that preclude the routine measurement of tension from single myocytes .…”

Section: Relationship Between Creep Currents and Mechanical Activitymentioning

confidence: 99%

"Creep currents" in single frog atrial cells may be generated by electrogenic Na/Ca exchange.

Hume¹,

Uehara²

1986

The Journal of General Physiology

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The objective of these experiments was to test the hypothesis that the "creep currents" induced by Na loading of single frog atrial cells (Hume, J . R ., and A . Uehara . 1986 . Journal of General Physiology. 87 :833) may be generated by an electrogenic Na/Ca exchanger . Creep currents induced by Na loading were examined over a wide range of membrane potentials . During depolarizing voltage-clamp pulses, outward creep currents were observed, followed by inward creep currents upon the return to the holding potential .During hyperpolarizing voltage-clamp pulses, creep currents of the opposite polarity were observed : inward creep currents were observed during the pulses, followed by outward creep currents upon the return to the holding potential . The current-voltage relations for inward and outward creep currents in response to depolarizing or hyperpolarizing voltage displacements away from the holding potential all intersect the voltage axis at a common potential, which indicates that inward and outward creep currents may have a common reversal potential under equilibrium conditions and may therefore be generated by a common mechanism . Measurements of inward creep currents confirm that voltage displacements away from the holding potential rapidly alter equilibrium conditions . Current-voltage relationships of inward creep currents after depo-

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Contractile force measured in unskinned isolated adult rat heart fibres

Cited by 66 publications

References 6 publications

Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions

Single cell mechanics of rat cardiomyocytes under isometric, unloaded, and physiologically loaded conditions

Contractile tension and beating rates of self-exciting monolayers and 3D-tissue constructs of neonatal rat cardiomyocytes

"Creep currents" in single frog atrial cells may be generated by electrogenic Na/Ca exchange.

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