Аннотация
1. Cytosolic free calcium ion concentration (Ca$^2+$i) and whole-cell
L-type Ca$^2+$ channel currents were measured during excitation-contraction
(E-C) coupling in single voltage-clamped rat cardiac ventricular
cells. The measurements were used to compute the total cellular efflux
of calcium ions through sarcoplasmic reticulum (SR) Ca$^2+$ release
channels (FSR,rel) and the influx of Ca$^2+$ via L-type Ca$^2+$
channels (FICa). 2. FSR,rel was elicited by depolarizing voltage-clamp
pulses 200 ms in duration to membrane potentials from -30 to +80
mV. Over this range, peak FSR,rel had a bell-shaped dependence on
clamp pulse potential. In all cells, the 'gain' of the system, measured
as the ratio, FSR,rel(max)/FICa(max), declined from about 16, at
0 mV, to much lower values as clamp pulse voltage was made progressively
more positive. We named this phenomenon of change in gain as a function
of membrane potential, 'variable gain'. At clamp pulse potentials
in the range -30 to 0 mV, the gain differed from cell to cell, being
constant at about 16 in some cells, but decreasing from high values
(approximately 65) at -20 mV in others. 3. At clamp pulse potentials
at which Ca$^2+$ influx (FICa) was maintained, FSR,rel also had
a small maintained component. When macroscopic Ca$^2+$ influx
was brief (1-2 ms, during 'tails' of FICa), FSR,rel rose rapidly
to a peak after repolarization and then declined with a half-time
of about 9 ms (typically). 4. The rising phase of Ca$^2+$i
transients could be interrupted by stopping Ca$^2+$ influx rapidly
(by voltage clamp). We therefore termed this phenomenon 'interrupted
SR Ca$^2+$ release'.(ABSTRACT TRUNCATED AT 250 WORDS)
Описание
The whole bibliography file I use.
Линки и ресурсы
тэги
- 8014907
- Aniline
- Animals,
- Calcium
- Calcium,
- Channel
- Channels,
- Compounds,
- Confocal,
- Contraction,
- Dyes,
- Electrophysiology,
- Fluorescent
- Gating,
- Gov't,
- Heart,
- In
- Ion
- Membrane
- Microscopy,
- Myocardial
- Myocardium,
- Non-P.H.S.,
- Non-U.S.
- P.H.S.,
- Patch-Clamp
- Potentials,
- Rats,
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- Ryanodine,
- Sarcopla,
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- Wistar,
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- smic