Zusammenfassung
Ca$^2+$ sparks are spatially localized intracellular Ca$^2+$
release events that were first described in 1993. Sparks have been
ascribed to sarcoplasmic reticulum Ca$^2+$ release channel (ryanodine
receptor, RyR) opening induced by Ca$^2+$ influx via L-type Ca$^2+$
channels or by spontaneous RyR openings and have been thought to
reflect Ca$^2+$ release from a cluster of RyR. Here we describe
a pharmacological approach to study sparks by exposing ventricular
myocytes to caffeine with a rapid solution-switcher device. Sparks
under these conditions have properties similar to naturally occurring
sparks in terms of size and intracellular Ca$^2+$ concentration
(Ca$^2+$(i)) amplitude. However, after the diffusion of caffeine,
sparks first appear close to the cell surface membrane before coalescing
to produce a whole cell transient. Our results support the idea that
a whole cell Ca$^2+$(i) transient consists of the summation
of sparks and that Ca$^2+$ sparks consist of the opening of a
cluster of RyR and confirm that characteristics of the cluster rather
than the L-type Ca$^2+$ channel-RyR relation determine spark
properties.
- 10666100
- animal,
- animals,
- aortic
- atpase,
- balb
- c,
- caffeine,
- calcium
- calcium,
- cardiac
- cardiomegaly,
- cells,
- channels,
- confocal,
- contraction,
- cultured,
- disease
- diseases,
- dyes,
- dysfunction,
- exchanger,
- female,
- fluorescence,
- fluorescent
- gov't,
- heart
- heart,
- homeostasis,
- humans,
- inbred
- intracellular
- l-type,
- left,
- low,
- male,
- membranes,
- mice,
- microscopy,
- models,
- muscle
- muscles,
- myocardial
- myocardium,
- non-p.h.s.,
- non-u.s.
- output,
- p.h.s.,
- research
- reticulum,
Nutzer