Abstract
We have used standard indirect immunofluorescence techniques in combination
with wide-field microscopy and image deconvolution to assess the
distribution of proteins implicated in excitation-contraction coupling
and Ca$^2+$ homeostasis in adult rat cardiomyocytes. We begin
by discussing our earlier results and summarizing what is known about
the molecular architecture of this species to provide a rationale
for the work presented here. The previous results showed that the
dyads contain Ca$^2+$ channels and ryanodine receptors, but few
Na$^+$ channels or Na$^+$/Ca$^2+$ exchangers. The latter
proteins were not colocalized elsewhere on the membrane, and we have
now found that they appear to be minimally associated with caveolin-3.
None of the molecules examined are distributed uniformly in the membranes
in which they are located but are organized into discrete clusters
attached to the underlying cytoskeleton, an arrangement that, at
the level of light microscopy, does not appear to be affected by
the enzymatic dissociation used to study single cells. Analysis of
how the clusters are organized and distributed throughout the volume
of the cell suggests that there may be differences in excitation-contraction
coupling between the cell surface and the interior.
- 12502603
- animals,
- calcium
- calcium,
- cell
- cells,
- channel,
- channels,
- gov't,
- membrane
- membrane,
- microdomains,
- muscle
- myocardium,
- non-u.s.
- rats,
- receptor
- release
- research
- reticulum,
- ryanodine
- sarcoplasmic
- support,
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