Title: Direct evidence of a Ca-sensitive inactivation of slow inward channels in frog atrial myocardium
Authors: Nilius, Bernd ×
Röder, A #
Issue Date: Jan-1986
Series Title: Biomedica biochimica acta. vol:44 issue:7-8 pages:1151-61
Abstract: Electrical properties of frog atrial myocardium under Ca-free conditions (30 min superfusion with 1 mM EGTA) were examined using a microelectrode and voltage clamp technique. Action potentials recorded from atrial trabeculae were extremely prolonged, up to more than 2 s. The resting potential was shifted towards more positive values (-60 +/- 9 mV (Ca-free); -75 +/- 4 mV (control); n = 6). Slow inward currents inactivated extremely slow showing time constants between 2 and 3 s. The voltage-dependence of the time constant of inactivation was found to be U-shaped in Ca-containing but bell-shaped in Ca-free solutions. After a 30 min Ca-free superfusion, the surfaces of the atrial trabeculae studied by scanning electron microscopy changes from being rough to extremely smooth, supposedly indicating a change in the surface coat. Using electron-microprobe analysis within a surface layer of about 0.2 micron thickness direct measurements of the Ca concentration showed a reduction under Ca-free conditions by more than 200-fold. Electrophysiological measurements, morphological findings and measurements of the Ca concentration in the surface region directly suggest the existence of a Ca-sensitive inactivation of slow channels in frog atrial myocardium.
ISSN: 0232-766X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Ion Channel Research
Department of Cellular and Molecular Medicine - miscellaneous
× corresponding author
# (joint) last author

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