Regulation of cardiac muscle Ca$^2+$ release channel by sarcoplasmic
reticulum lumenal Ca$^2+$.
L. Xu, and G. Meissner. Biophys. J., 75 (5):
2302--2312(November 1998)
Abstract
The cardiac muscle sarcoplasmic reticulum Ca$^2+$ release channel
(ryanodine receptor) is a ligand-gated channel that is activated
by micromolar cytoplasmic Ca$^2+$ concentrations and inactivated
by millimolar cytoplasmic Ca$^2+$ concentrations. The effects
of sarcoplasmic reticulum lumenal Ca$^2+$ on the purified release
channel were examined in single channel measurements using the planar
lipid bilayer method. In the presence of caffeine and nanomolar cytosolic
Ca$^2+$ concentrations, lumenal-to-cytosolic Ca$^2+$ fluxes
>/=0.25 pA activated the channel. At the maximally activating cytosolic
Ca$^2+$ concentration of 4 microM, lumenal Ca$^2+$ fluxes
of 8 pA and greater caused a decline in channel activity. Lumenal
Ca$^2+$ fluxes primarily increased channel activity by increasing
the duration of mean open times. Addition of the fast Ca$^2+$-complexing
buffer 1,2-bis(2-aminophenoxy)ethanetetraacetic acid (BAPTA) to the
cytosolic side of the bilayer increased lumenal Ca$^2+$-activated
channel activities, suggesting that it lowered Ca$^2+$ concentrations
at cytosolic Ca$^2+$-inactivating sites. Regulation of channel
activities by lumenal Ca$^2+$ could be also observed in the absence
of caffeine and in the presence of 5 mM MgATP. These results suggest
that lumenal Ca$^2+$ can regulate cardiac Ca$^2+$ release
channel activity by passing through the open channel and binding
to the channel's cytosolic Ca$^2+$ activation and inactivation
sites.
%0 Journal Article
%1 Xu_1998_2302
%A Xu, L.
%A Meissner, G.
%D 1998
%J Biophys. J.
%K 9788925 Acid, Adenosine Animals, Binding Blockers, Caffeine, Calcium Calcium, Calcium-Binding Cells, Channel Channel, Channels, Chimeric Cultured, Dogs, Egtazic Electrophysiology, Gov't, Heart, Humans, Immunophilins, Isoforms, Liposomes, Magnesium, Mammals, Muscle, Myocardium, Non-U.S. P.H.S., Protein Proteins, Receptor Release Research Reticulum, Ryanodine Ryanodine, Sarcoplasmic Skeletal, Support, Tacrolimus Tacrolimus, Triphosphate, Tritium, U.S.
%N 5
%P 2302--2312
%T Regulation of cardiac muscle Ca$^2+$ release channel by sarcoplasmic
reticulum lumenal Ca$^2+$.
%U http://www.biophysj.org/cgi/content/full/75/5/2302
%V 75
%X The cardiac muscle sarcoplasmic reticulum Ca$^2+$ release channel
(ryanodine receptor) is a ligand-gated channel that is activated
by micromolar cytoplasmic Ca$^2+$ concentrations and inactivated
by millimolar cytoplasmic Ca$^2+$ concentrations. The effects
of sarcoplasmic reticulum lumenal Ca$^2+$ on the purified release
channel were examined in single channel measurements using the planar
lipid bilayer method. In the presence of caffeine and nanomolar cytosolic
Ca$^2+$ concentrations, lumenal-to-cytosolic Ca$^2+$ fluxes
>/=0.25 pA activated the channel. At the maximally activating cytosolic
Ca$^2+$ concentration of 4 microM, lumenal Ca$^2+$ fluxes
of 8 pA and greater caused a decline in channel activity. Lumenal
Ca$^2+$ fluxes primarily increased channel activity by increasing
the duration of mean open times. Addition of the fast Ca$^2+$-complexing
buffer 1,2-bis(2-aminophenoxy)ethanetetraacetic acid (BAPTA) to the
cytosolic side of the bilayer increased lumenal Ca$^2+$-activated
channel activities, suggesting that it lowered Ca$^2+$ concentrations
at cytosolic Ca$^2+$-inactivating sites. Regulation of channel
activities by lumenal Ca$^2+$ could be also observed in the absence
of caffeine and in the presence of 5 mM MgATP. These results suggest
that lumenal Ca$^2+$ can regulate cardiac Ca$^2+$ release
channel activity by passing through the open channel and binding
to the channel's cytosolic Ca$^2+$ activation and inactivation
sites.
@article{Xu_1998_2302,
abstract = {The cardiac muscle sarcoplasmic reticulum {C}a$^{2+}$ release channel
(ryanodine receptor) is a ligand-gated channel that is activated
by micromolar cytoplasmic {C}a$^{2+}$ concentrations and inactivated
by millimolar cytoplasmic {C}a$^{2+}$ concentrations. The effects
of sarcoplasmic reticulum lumenal {C}a$^{2+}$ on the purified release
channel were examined in single channel measurements using the planar
lipid bilayer method. In the presence of caffeine and nanomolar cytosolic
{C}a$^{2+}$ concentrations, lumenal-to-cytosolic {C}a$^{2+}$ fluxes
>/=0.25 pA activated the channel. At the maximally activating cytosolic
{C}a$^{2+}$ concentration of 4 microM, lumenal {C}a$^{2+}$ fluxes
of 8 pA and greater caused a decline in channel activity. Lumenal
{C}a$^{2+}$ fluxes primarily increased channel activity by increasing
the duration of mean open times. Addition of the fast {C}a$^{2+}$-complexing
buffer 1,2-bis(2-aminophenoxy)ethanetetraacetic acid (BAPTA) to the
cytosolic side of the bilayer increased lumenal {C}a$^{2+}$-activated
channel activities, suggesting that it lowered {C}a$^{2+}$ concentrations
at cytosolic {C}a$^{2+}$-inactivating sites. Regulation of channel
activities by lumenal {C}a$^{2+}$ could be also observed in the absence
of caffeine and in the presence of 5 mM MgATP. These results suggest
that lumenal {C}a$^{2+}$ can regulate cardiac {C}a$^{2+}$ release
channel activity by passing through the open channel and binding
to the channel's cytosolic {C}a$^{2+}$ activation and inactivation
sites.},
added-at = {2009-06-03T11:20:58.000+0200},
author = {Xu, L. and Meissner, G.},
biburl = {https://www.bibsonomy.org/bibtex/20deae75665c24182a291d00c7550885e/hake},
description = {The whole bibliography file I use.},
file = {Xu_1998_2302.pdf:Xu_1998_2302.pdf:PDF},
interhash = {26270067ef72bc63d731b623147fecc5},
intrahash = {0deae75665c24182a291d00c7550885e},
journal = {Biophys. J.},
key = 215,
keywords = {9788925 Acid, Adenosine Animals, Binding Blockers, Caffeine, Calcium Calcium, Calcium-Binding Cells, Channel Channel, Channels, Chimeric Cultured, Dogs, Egtazic Electrophysiology, Gov't, Heart, Humans, Immunophilins, Isoforms, Liposomes, Magnesium, Mammals, Muscle, Myocardium, Non-U.S. P.H.S., Protein Proteins, Receptor Release Research Reticulum, Ryanodine Ryanodine, Sarcoplasmic Skeletal, Support, Tacrolimus Tacrolimus, Triphosphate, Tritium, U.S.},
month = Nov,
number = 5,
pages = {2302--2312},
pmid = {9788925},
timestamp = {2009-06-03T11:21:38.000+0200},
title = {Regulation of cardiac muscle {C}a$^{2+}$ release channel by sarcoplasmic
reticulum lumenal {C}a$^{2+}$.},
url = {http://www.biophysj.org/cgi/content/full/75/5/2302},
volume = 75,
year = 1998
}