Beat-to-beat oscillations of mitochondrial [Ca2+] in cardiac cells.
The Ca2+-sensitive photoprotein aequorin and the new green fluorescent protein-based fluorescent Ca2+ indicators 'ratiometric-pericam' were selectively expressed in the mitochondria, cytosol and/or nucleus of spontaneously beating ventricular myocytes from neonatal rats. This combined strategy reveals that mitochondrial [Ca2+] oscillates rapidly and in synchrony with cytosolic and nuclear [Ca2+]. The Ca2+ oscillations were reduced in frequency and/or amplitude by verapamil and carbachol and were enhanced by isoproterenol and elevation of extracellular [Ca2+]. An increased frequency and/or amplitude of cytosolic Ca2+ spikes was rapidly mirrored by similar changes in mitochondrial Ca2+ spikes and more slowly by elevations of the interspike Ca2+ levels. The present data unequivocally demonstrate that in cardiac cells mitochondrial [Ca2+] oscillates synchronously with cytosolic [Ca2+] and that mitochondrial Ca2+ handling rapidly adapts to inotropic or chronotropic inputs.
Robert
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V
Department of Biomedical Sciences, CNR Center of Biomembranes, University of Padua, Via Colombo 3, 35121 Padua, Italy. pozzant@civ.bio.unipd.it
Gurlini
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P
Tosello
V
V
Nagai
T
T
Miyawaki
A
A
Di Lisa
F
F
Pozzan
T
T
D000331:Aequorin / Q000032:analysis / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002467:Cell Nucleus / Q000502:physiology; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles; D006801:Humans; D008164:Luminescent Proteins / Q000032:analysis; D008928:Mitochondria / Q000502:physiology; D008929:Mitochondria, Heart / Q000502:physiology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009991:Oscillometry; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000032:analysis; D014162:Transfection
D008164:Luminescent Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D000331:Aequorin; D002118:Calcium