Presence of store-operated Ca2+ entry in C57BL/6J mouse ventricular myocytes and its suppression by sevoflurane.
BACKGROUND
Store-operated Ca(2+) entry (SOCE) has been implicated in various pathological conditions of the heart including ischaemia/reperfusion and ventricular hypertrophy. This study investigated the effects of sevoflurane on SOCE.


METHODS
Fluorescence imaging was performed on fluo-3- and mag-fluo-4-loaded mouse ventricular myocytes to measure the cytosolic and intraluminal sarcoplasmic reticulum (SR) Ca(2+) levels, respectively, using a confocal laser scanning microscope. Whole-cell membrane currents were recorded using the patch-clamp technique. Ventricular myocytes were exposed to thapsigargin and angiotensin II to deplete SR Ca(2+) stores and thereby activate SOCE.


RESULTS
The combined application of thapsigargin and angiotensin II to the Ca(2+)-free medium evoked a significant decrease in the SR Ca(2+) levels, which was followed by the elevation of cytosolic Ca(2+) and the development of cellular hypercontracture upon subsequent addition of extracellular Ca(2+). This cytosolic Ca(2+) elevation was inhibited by 2-aminoethoxydiphenyl borate but not by verapamil and KB-R7943, which indicates that SOCE was present in mouse ventricular myocytes. Sevoflurane concentration-dependently inhibited the SOCE-mediated Ca(2+) overload (IC(50) of 137 μM, which corresponds to 0.96%) with a significant reduction occurring at concentrations of ≥2%. Patch-clamp experiments revealed that the SOCE current was also concentration-dependently blocked by sevoflurane (IC(50) of 144 μM, which corresponds to 1.0%).


CONCLUSIONS
Sevoflurane at concentrations of ≥2% significantly inhibits the SOCE activity and prevents the resultant cellular Ca(2+) overload that leads to hypercontracture in ventricular myocytes. This inhibitory action may be involved in the cardioprotective effect of sevoflurane against Ca(2+) overload-mediated injury.
Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan. akiko77@belle.shiga-med.ac.jp
A
A
Kojima
H
H
Kitagawa
M
M
Omatsu-Kanbe
H
H
Matsuura
S
S
Nosaka
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006352:Heart Ventricles / Q000187:drug effects; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D019837:Ryanodine Receptor Calcium Release Channel; D000077149:Sevoflurane; D002118:Calcium