A photoelectric recording set for pulsation curves of heart muscle cultures in vitro

Bucher, Otto

doi:10.1016/0014-4827(57)90050-2

Cited by 16 publications

(7 citation statements)

References 3 publications

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“…But, because the action potential is accompanied by contraction, it is necessary to distinguish between the optical signal resulting from the voltage sensitivity of the dye and the signal produced by the effects of contraction.' 'Included among the effects of contraction upon the optical signal in both stained and unstained tissue are movement-related contributions as seen in cultured heart tissue (Bucher, 1957;Sinclair, Miller and Harrison, 1970;Boder, Harley, and Johnson, 1971;Clusin, 1980) and in isolated cardiac Purkinje fibers (Kass, 1981). Other contraction related events such as changes in tissue thickness, slope, and contractile proteins could also contribute to the signal, which we found to be wavelength and location dependent in sinoatrial tissue.…”

Section: Introductionmentioning

confidence: 77%

Voltage-sensitive dyes. Discerning contraction and electrical signals in myocardium

Hill¹,

Courtney²

1982

Biophysical Journal

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Muscle contraction can introduce artifact in attempted optical measurements of the action potential in heart tissue stained with voltage-sensitive dyes. Using rabbit sinus node and atrial tissue in vitro, we found that the voltage-sensitive part of the optical signal remains relatively unchanged by variations in the rate of external stimulation or by the application of transmural stimulation (TS), while the contraction-related component can be significantly increased by these same interventions. The relative contributions of membrane voltage and contraction to the optical signal can thus be determined. In particular, the rapid upstroke component of the action potential can be easily identified using this technique.

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Section: Introductionmentioning

confidence: 77%

Voltage-sensitive dyes. Discerning contraction and electrical signals in myocardium

Hill¹,

Courtney²

1982

Biophysical Journal

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“…The microphotometer output, filtered above 200 Hz, was displayed on an oscilloscope and recorded on an oscillograph. With this photomultiplier, variations in the transmittance of light were measured (14) in an area of the cell limited by a calibrated diaphragm. When a cell thickened during contraction, its optical density increased and the transmittance of light decreased.…”

Section: Mechanical Recordingsmentioning

confidence: 99%

Excitation-Contraction Coupling of Isolated Cardiac Fibers with Disrupted or Closed Sarcolemmas: CALCIUM-DEPENDENT CYCLIC AND TONIC CONTRACTIONS

Fabiato

1972

Circulation Research

214

120

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Single cells of adult rat ventricle were separated with 0.1% trypsin and 0.05-0.1% collagenase. Ten percent of these cells were tubular and striated, contracted spontaneously in the presence of 0.05 mM CaCl 2 or after addition of 0.1-0.5 mM CaCl 2 , and developed con fracture in 1 mM CaCl 2 . A resting potential of -30 to -50 mv and an action potential more than 100 msec in duration were recorded in some of the cells. These relatively intact cells were contrasted with myocardial fibers (10-lOOyu,) obtained by homogenization. In the presence of 0.025 mM ethyleneglycol bis(y3-aminoethylether)-N, N'tetraacetic acid (EGTA), localized cyclic contractions with intracellular asynchrony were observed under the phase microscope in obviously disrupted areas of these mechanically separated fibers. These contractions were insensitive to the ratio of Na + to K + , and neither resting potentials nor action potentials were observed. Thus, these disrupted fibers were considered skinned fibers of cardiac muscle; this assumption was further supported by the absence of modification of fiber sensitivity to Ca 2+ by simultaneous skinning with EDTA. Effects of Ca 2+ were studied with control of pCa in the medium by EGTA-Ca buffers, either directly on the homogenate or after depletion of Ca 2+ content of the tissue. At 22°C, pH 7.0, and in the presence of 4 mM MgCL, 5 mM adenosine triphosphate, and 2 mM EGTA, cyclic contractions were inhibited and a tonic contraction was induced at a pCa of 6.25-6.5, which represented the threshold for activation of myofilaments. With the same medium but with low EGTA (less than 0.2 mM), cyclic contractions were obtained if pCa was equal to or lower than 7.4-7.6. Therefore, these contractions corresponded to a cyclic release of Ca 2+ from cellular stores, yielding a transient activation of myofilaments. This large release of Ca 2 + within the fiber was induced by a small addition of Ca 2+ to the medium. It was concluded that a regenerative release of Ca 2+ could be demonstrated in heart muscle under these conditions. Localized cyclic contractions were not observed in disrupted fibers of frog heart, in which spontaneously beating cells could be separated with enzymes.

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“…One difficulty with these cell preparations is that their small size does not permit the use of force transducers to measure contractile responses in the usual way. Optical techniques for recording edge movement have therefore been devised (Bucher, 1957) and several studies have used these techniques to demonstrate ionotropic drug effects (Sinclair, Miller & Harrison, 1970;Boder, Harley & Johnson, 1971; Barry, Pitzen, Protas & Harrison, 1975. The inference of contractile force from edge movement seems reasonable, since mechanical deformation of a material must reflect the magnitude of the stresses that produce it.…”

mentioning

confidence: 99%

The mechanical activity of chick embryonic myocardial cell aggregates

Clusin¹,

Hamilton²,

Nelson³

1981

The Journal of Physiology

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SUMMARY1. Simultaneous recordings of membrane potential and edge movement were obtained in spontaneously beating chick embryonic myocardial cell aggregates, which are known to behave as an isopotential syncytium.2. The time course of edge movement was similar in different aggregates, and in different regions of the same aggregate.3. Peak amplitude was increased by 10-6 M-ouabain, and by rapid reduction of the external sodium concentration.4. Peak amplitude was decreased during single premature action potentials, but sustained rapid pacing produced an ascending staircase.5. Depolarizing current pulses increased both the amplitude and duration of the contraction, and caused potentiation ofthe next spontaneous beat. Edge displacement during a series of pulses was a monotonic function of membrane potential.6. Edge movement between action potentials (diastolic movement) was well fitted by an exponential with a mean time constant of 69 msec. Diastolic edge movement was due to a weak, slowly decaying contractile force, which was demonstrated in cells grown on a linear-elastic nylon bristle.7. The time course of diastolic edge movement remained constant, or nearly constant, during variations in peak amplitude that resulted from prematurity of the action potential, exposure to 10-6 m-ouabain, spontaneous mechanical alternans, or prolongation of the action potential by current pulses.8. In contrast, reduction of the external sodium concentration produced marked, selective slowing of the diastolic edge movement. Similar slowing occurred during cooling and during staircase. Diastolic edge movement was selectively accelerated when the preceding interbeat interval was prolonged by a hyperpolarizing current pulse.9. The above observations are consistent with the hypothesis that edge displacement is a monotonic function of contractile force.10. The slow relaxation between action potentials probably reflects removal of intracellular calcium across the surface membrane in exchange for sodium. Changes in the rate of calcium removal may play a role in the regulation of contractility in this tissue.

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A photoelectric recording set for pulsation curves of heart muscle cultures in vitro

Cited by 16 publications

References 3 publications

Voltage-sensitive dyes. Discerning contraction and electrical signals in myocardium

Voltage-sensitive dyes. Discerning contraction and electrical signals in myocardium

Excitation-Contraction Coupling of Isolated Cardiac Fibers with Disrupted or Closed Sarcolemmas: CALCIUM-DEPENDENT CYCLIC AND TONIC CONTRACTIONS

The mechanical activity of chick embryonic myocardial cell aggregates

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