We have characterized modulation of ICa by Ca$^2+$ at the t-tubules
(ie, in control cells) and surface sarcolemma (ie, in detubulated
cells) of cardiac ventricular myocytes, using the whole-cell patch
clamp technique to record ICa. ICa inactivation was significantly
slower in detubulated cells than in control cells (27.1+/-7.8 ms,
n=22, versus 16.4+/-7.9 ms, n=22; P<0.05). In atrial myocytes, which
lack t-tubules, ICa inactivation was not changed by the treatment
used to produce detubulation. In the presence of ryanodine or BAPTA,
or when Ba2+ was used as the charge carrier, the rate of inactivation
was not significantly different in control and detubulated cells.
Frequency-dependent facilitation occurred in control cells but not
in detubulated cells, and was abolished by ryanodine. These results
suggest that Ca$^2+$ released from the SR has a greater effect
on ICa in the t-tubules than at the surface sarcolemma. This does
not appear to be due to differences in local Ca$^2+$ release
from the SR, because the gain of Ca$^2+$ release was not significantly
different in control and detubulated cells. These data suggest that
the t-tubules are a key site for the regulation of transsarcolemmal
Ca$^2+$ flux by Ca$^2+$ release from the SR; this could play
a role in altered Ca$^2+$ homeostasis in pathological conditions.
The full text of this article is available online at http://circres.ahajournals.org.
%0 Journal Article
%1 Bret_2004_e1
%A Brette, Fabien
%A Sall�, Laurent
%A Orchard, Clive H
%D 2004
%J Circ. Res.
%K 15192026 Animals, Calcium Calcium, Cardiac, Cell Cells, Channels, Conductivity, Cultu, Electric Gov't, Heart L-Type, Membrane, Myocytes, Non-U.S. Patch-Clamp Rats, Research Reticulum, Sarcoplasmic Support, Techniques, Ventricles, Wistar, red,
%N 1
%P e1--e7
%R 10.1161/01.RES.0000135547.53927.F6
%T Differential modulation of L-type Ca$^2+$ current by SR Ca$^2+$
release at the T-tubules and surface membrane of rat ventricular
myocytes.
%U http://dx.doi.org/10.1161/01.RES.0000135547.53927.F6
%V 95
%X We have characterized modulation of ICa by Ca$^2+$ at the t-tubules
(ie, in control cells) and surface sarcolemma (ie, in detubulated
cells) of cardiac ventricular myocytes, using the whole-cell patch
clamp technique to record ICa. ICa inactivation was significantly
slower in detubulated cells than in control cells (27.1+/-7.8 ms,
n=22, versus 16.4+/-7.9 ms, n=22; P<0.05). In atrial myocytes, which
lack t-tubules, ICa inactivation was not changed by the treatment
used to produce detubulation. In the presence of ryanodine or BAPTA,
or when Ba2+ was used as the charge carrier, the rate of inactivation
was not significantly different in control and detubulated cells.
Frequency-dependent facilitation occurred in control cells but not
in detubulated cells, and was abolished by ryanodine. These results
suggest that Ca$^2+$ released from the SR has a greater effect
on ICa in the t-tubules than at the surface sarcolemma. This does
not appear to be due to differences in local Ca$^2+$ release
from the SR, because the gain of Ca$^2+$ release was not significantly
different in control and detubulated cells. These data suggest that
the t-tubules are a key site for the regulation of transsarcolemmal
Ca$^2+$ flux by Ca$^2+$ release from the SR; this could play
a role in altered Ca$^2+$ homeostasis in pathological conditions.
The full text of this article is available online at http://circres.ahajournals.org.
@article{Bret_2004_e1,
abstract = {We have characterized modulation of ICa by {C}a$^{2+}$ at the t-tubules
(ie, in control cells) and surface sarcolemma (ie, in detubulated
cells) of cardiac ventricular myocytes, using the whole-cell patch
clamp technique to record ICa. ICa inactivation was significantly
slower in detubulated cells than in control cells (27.1+/-7.8 ms,
n=22, versus 16.4+/-7.9 ms, n=22; P<0.05). In atrial myocytes, which
lack t-tubules, ICa inactivation was not changed by the treatment
used to produce detubulation. In the presence of ryanodine or BAPTA,
or when Ba2+ was used as the charge carrier, the rate of inactivation
was not significantly different in control and detubulated cells.
Frequency-dependent facilitation occurred in control cells but not
in detubulated cells, and was abolished by ryanodine. These results
suggest that {C}a$^{2+}$ released from the SR has a greater effect
on ICa in the t-tubules than at the surface sarcolemma. This does
not appear to be due to differences in local {C}a$^{2+}$ release
from the SR, because the gain of {C}a$^{2+}$ release was not significantly
different in control and detubulated cells. These data suggest that
the t-tubules are a key site for the regulation of transsarcolemmal
{C}a$^{2+}$ flux by {C}a$^{2+}$ release from the SR; this could play
a role in altered {C}a$^{2+}$ homeostasis in pathological conditions.
The full text of this article is available online at http://circres.ahajournals.org.},
added-at = {2009-06-03T11:20:58.000+0200},
author = {Brette, Fabien and Sall�, Laurent and Orchard, Clive H},
biburl = {https://www.bibsonomy.org/bibtex/26f8109983d2366d41af05622185d72bd/hake},
description = {The whole bibliography file I use.},
doi = {10.1161/01.RES.0000135547.53927.F6},
file = {Bret_2004_e1.pdf:Bret_2004_e1.pdf:PDF},
interhash = {9d12b0dbf2cb5540c5193f2a6920d0bc},
intrahash = {6f8109983d2366d41af05622185d72bd},
journal = {Circ. Res.},
key = 226,
keywords = {15192026 Animals, Calcium Calcium, Cardiac, Cell Cells, Channels, Conductivity, Cultu, Electric Gov't, Heart L-Type, Membrane, Myocytes, Non-U.S. Patch-Clamp Rats, Research Reticulum, Sarcoplasmic Support, Techniques, Ventricles, Wistar, red,},
month = Jul,
number = 1,
pages = {e1--e7},
pii = {01.RES.0000135547.53927.F6},
pmid = {15192026},
timestamp = {2009-06-03T11:21:06.000+0200},
title = {Differential modulation of L-type {C}a$^{2+}$ current by SR {C}a$^{2+}$
release at the T-tubules and surface membrane of rat ventricular
myocytes.},
url = {http://dx.doi.org/10.1161/01.RES.0000135547.53927.F6},
volume = 95,
year = 2004
}