[Acidosis is associated with an intracellular accumulation of Ca2+. Its role in the modulation of myocardial contractility].
Myocardial acidosis, as during ischemia, profoundly modifies excitation-contraction mechanisms. The decreased myofilament sensitivity to Ca2+ reduces contractility regardless of an intracellular accumulation of Ca2+. To determine the source for this increase in Ca2+ we evaluated the effect of acidosis on diastolic [Ca2+] and mitochondrial [Ca2+]. We used single cardiac cells loaded with the fluorescent probes, indo-1 for Ca2+ and SNARF-1 for pH. Acidosis increases [Ca2+] both in cytosol and mitochondria. The cytosolic accumulation depends, most likely, on an active release from mitochondria. A competition among Ca2+ and H+ ions may, instead, explains the increase in mitochondrial [Ca2+].
Gambassi
G
G
Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD.
Capogrossi
M C
MC
D000138:Acidosis / Q000503:physiopathology*; D000818:Animals; D001578:Benzopyrans; D002118:Calcium / Q000502:physiology*; D009202:Cardiomyopathies / Q000503:physiopathology*; D005453:Fluorescence; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007211:Indoles; D008929:Mitochondria, Heart / Q000502:physiology; D009200:Myocardial Contraction / Q000502:physiology*; D051381:Rats
D001578:Benzopyrans; D005456:Fluorescent Dyes; D007211:Indoles; C063917:SNARF dye; C048960:indo-1; D002118:Calcium
L'acidosi è associata ad un accumulo intracellulare di Ca2+. Ruolo nella modulazione della contrattilità miocardica.