Detubulation of rat ventricular myocytes has been used to investigate
the role of the t-tubules in Ca$^2+$ cycling during excitation-contraction
coupling in rat ventricular myocytes. Ca$^2+$ was monitored using
fluo-3 and confocal microscopy. In control myocytes, electrical stimulation
caused a spatially uniform increase in intracellular Ca$^2+$
across the cell width. After detubulation, Ca$^2+$ rose initially
at the cell periphery and then propagated into the center of the
cell. Application of caffeine to control myocytes resulted in a rapid
and uniform increase of intracellular Ca$^2+$; the distribution
and amplitude of this increase was the same in detubulated myocytes,
although its decline was slower. On application of caffeine to control
cells, there was a large, rapid, and transient rise in extracellular
Ca$^2+$ as Ca$^2+$ was extruded from the cell; this rise
was significantly smaller in detubulated cells, and the remaining
increase was blocked by the sarcolemmal Ca$^2+$ ATPase inhibitor
carboxyeosin. The treatment used to produce detubulation had no significant
effect on Ca$^2+$ efflux in atrial cells, which lack t-tubules.
Detubulation of ventricular myocytes also resulted in loss of Na$^+$-Ca$^2+$
exchange current, although the density of the fast Na$^+$ current
was unaltered. It is concluded that Na$^+$-Ca$^2+$ exchange
function, and hence Ca$^2+$ efflux by this mechanism, is concentrated
in the t-tubules, and that the concentration of Ca$^2+$ flux
pathways in the t-tubules is important in producing a uniform increase
in intracellular Ca$^2+$ on stimulation.
%0 Journal Article
%1 Yang_2002_315
%A Yang, Z.
%A Pascarel, C.
%A Steele, D. S.
%A Komukai, K.
%A Brette, F.
%A Orchard, C. H.
%D 2002
%J Circ. Res.
%K 12193458 Action Adenosinetriphosphatase, Agents, Animals, Atria, Caffeine, Calcium, Capacitance, Cardiotonic Cell Compounds, Confocal, Dyes, Electric Electrophysiology, Enzyme Exchanger, Fibers, Fluid, Fluorescent Formamides, Gov't, Heart Inhibitors, Intracellular Isoproterenol, Membrane Microscopy, Microtubules, Muscle Myocardium, Nickel, Non-U.S. Patch-Clamp Potentials, Pyridinium Rats, Research Sarcolemma, Separation, Sodium-Calcium Stimulation, Structures, Support, Techniques, Ventricles, Wistar,
%N 4
%P 315-22
%T Na$^+$-Ca$^2+$ exchange activity is localized in the T-tubules
of rat ventricular myocytes.
%U http://circres.ahajournals.org/cgi/content/full/91/4/315
%V 91
%X Detubulation of rat ventricular myocytes has been used to investigate
the role of the t-tubules in Ca$^2+$ cycling during excitation-contraction
coupling in rat ventricular myocytes. Ca$^2+$ was monitored using
fluo-3 and confocal microscopy. In control myocytes, electrical stimulation
caused a spatially uniform increase in intracellular Ca$^2+$
across the cell width. After detubulation, Ca$^2+$ rose initially
at the cell periphery and then propagated into the center of the
cell. Application of caffeine to control myocytes resulted in a rapid
and uniform increase of intracellular Ca$^2+$; the distribution
and amplitude of this increase was the same in detubulated myocytes,
although its decline was slower. On application of caffeine to control
cells, there was a large, rapid, and transient rise in extracellular
Ca$^2+$ as Ca$^2+$ was extruded from the cell; this rise
was significantly smaller in detubulated cells, and the remaining
increase was blocked by the sarcolemmal Ca$^2+$ ATPase inhibitor
carboxyeosin. The treatment used to produce detubulation had no significant
effect on Ca$^2+$ efflux in atrial cells, which lack t-tubules.
Detubulation of ventricular myocytes also resulted in loss of Na$^+$-Ca$^2+$
exchange current, although the density of the fast Na$^+$ current
was unaltered. It is concluded that Na$^+$-Ca$^2+$ exchange
function, and hence Ca$^2+$ efflux by this mechanism, is concentrated
in the t-tubules, and that the concentration of Ca$^2+$ flux
pathways in the t-tubules is important in producing a uniform increase
in intracellular Ca$^2+$ on stimulation.
@article{Yang_2002_315,
abstract = {Detubulation of rat ventricular myocytes has been used to investigate
the role of the t-tubules in {C}a$^{2+}$ cycling during excitation-contraction
coupling in rat ventricular myocytes. {C}a$^{2+}$ was monitored using
fluo-3 and confocal microscopy. In control myocytes, electrical stimulation
caused a spatially uniform increase in intracellular [{C}a$^{2+}$]
across the cell width. After detubulation, [{C}a$^{2+}$] rose initially
at the cell periphery and then propagated into the center of the
cell. Application of caffeine to control myocytes resulted in a rapid
and uniform increase of intracellular [{C}a$^{2+}$]; the distribution
and amplitude of this increase was the same in detubulated myocytes,
although its decline was slower. On application of caffeine to control
cells, there was a large, rapid, and transient rise in extracellular
[{C}a$^{2+}$] as {C}a$^{2+}$ was extruded from the cell; this rise
was significantly smaller in detubulated cells, and the remaining
increase was blocked by the sarcolemmal {C}a$^{2+}$ ATPase inhibitor
carboxyeosin. The treatment used to produce detubulation had no significant
effect on {C}a$^{2+}$ efflux in atrial cells, which lack t-tubules.
Detubulation of ventricular myocytes also resulted in loss of {N}a$^{+}$-{C}a$^{2+}$
exchange current, although the density of the fast {N}a$^{+}$ current
was unaltered. It is concluded that {N}a$^{+}$-{C}a$^{2+}$ exchange
function, and hence {C}a$^{2+}$ efflux by this mechanism, is concentrated
in the t-tubules, and that the concentration of {C}a$^{2+}$ flux
pathways in the t-tubules is important in producing a uniform increase
in intracellular {C}a$^{2+}$ on stimulation.},
added-at = {2009-06-03T11:20:58.000+0200},
author = {Yang, Z. and Pascarel, C. and Steele, D. S. and Komukai, K. and Brette, F. and Orchard, C. H.},
biburl = {https://www.bibsonomy.org/bibtex/2a47c7bcae8f91809bf3286ace3ad6441/hake},
description = {The whole bibliography file I use.},
file = {Yang_2002_315.pdf:Yang_2002_315.pdf:PDF},
interhash = {7b4fa94537380e8068a0ea46f51d112f},
intrahash = {a47c7bcae8f91809bf3286ace3ad6441},
journal = {Circ. Res.},
key = 84,
keywords = {12193458 Action Adenosinetriphosphatase, Agents, Animals, Atria, Caffeine, Calcium, Capacitance, Cardiotonic Cell Compounds, Confocal, Dyes, Electric Electrophysiology, Enzyme Exchanger, Fibers, Fluid, Fluorescent Formamides, Gov't, Heart Inhibitors, Intracellular Isoproterenol, Membrane Microscopy, Microtubules, Muscle Myocardium, Nickel, Non-U.S. Patch-Clamp Potentials, Pyridinium Rats, Research Sarcolemma, Separation, Sodium-Calcium Stimulation, Structures, Support, Techniques, Ventricles, Wistar,},
month = Aug,
number = 4,
pages = {315-22},
timestamp = {2009-06-03T11:21:38.000+0200},
title = {{N}a$^{+}$-{C}a$^{2+}$ exchange activity is localized in the T-tubules
of rat ventricular myocytes.},
url = {http://circres.ahajournals.org/cgi/content/full/91/4/315},
volume = 91,
year = 2002
}