Effect of blockers of sarcolemmal iontransportingsystems on intensivity of heart dammage duringcalcium paradox
V. V. Alabovsky, Cragoe E. J., Jr., A. A. Winokurov
Department of Biochemistry of Medical Academy, Voronezh, Russia
Abstract
The aim of present study was to investigate a role of different anions in calcium
paradox development. It is accepted point of view that development of calcium paradox
is depent on cation composition and activity of Na/Ca exchange. However, role of
anion composition remain unknown. It is not studied role of some aniontransporting
systems in development of calcium paradox. Experiments were carried out on isolated
Langendorff perfused rat hearts. Hearts were perfused with calcium – containing
solution for 15 minutes, calcium – free medium for 10 minutes and reperfused by
initial calcium- containing solution with [Ca 2+ = 2 mM]. Release of myoglobin was
used as a marker of membrane damage. It has been shown that addition of 5—20 mM
HCO 3 exacerbated calcium paradox of the heart, elevated myoglobin release from
4,92±0,57 mcg/g dry weight to 11,3±1,6 mcg/g dry weight. An inhibitor of HCO 3/Cl
exchange, 10 mcM L-644,711 depressed elevation of myoglobin release to 4,8± 1,05
mcg/g dry weight. An inhibitor of Cl– channels, 5 mcM DIOA caused raising of
myoglobin loss to 7,3±0,8 mcg/g dry weight during calcium paradox. These data
show dependence of calcium paradox on anion composition. A possible reason for
exacerbation of calcium paradox by HCO3- rich medium could be consistence of
HCO 3/Cl and Na/Ca exchange. The results discover new perspectives in myocardial
protection of calcium overload.
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