Activation and Inactivation of Mechanosensitive Currents in the Chick Heart |
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Authors: | GCL Bett F Sachs |
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Institution: | (1) Department of Physiology and Biophysics, 124 Sherman Hall, SUNY, Buffalo, NY 14214, USA, US |
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Abstract: | The behavior of MS channels in embryonic chick ventricular myocytes activated by direct mechanical stimulation is strongly
affected by inactivation. The amplitude of the current is dependent not only on the amplitude of the stimulus, but also the
history of stimulation. The MS current inactivation appears to be composed of at least two contributions: (i) rearrangement
of the cortical tension transducing elements and (ii) blocking action of an autocrine agent released from the cell.
With discrete mechanical stimuli, the MS current amplitude in the second press of a double press protocol was always smaller
than the amplitude of the first MS current. Occasionally, a large MS current occurred when the cell was first stimulated,
but subsequently the cell became unresponsive. For a series of stimuli of varying amplitudes, the order in which they were
applied to the cell affected the size of the observed MS current for a given stimulus magnitude.
When continuous sinusoidal stimulation was applied to the cells, the MS current envelope either reached a steady state, or
inactivated. With sinusoidal stimulation, the MS response could be enhanced or restored by simple perfusion of fluid across
the cell. This suggests that mechanical stimulation of the cells produces an autocrine inhibitor of MS channels as well as
resulting in cortical rearrangement.
Received: 7 July 1999/Revised: 26 October 1999 |
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Keywords: | : Stretch — Voltage clamp — Mechanotransduction — Patch clamp — Modeling |
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