Contribution of ATP synthase to stimulation of respiration by Ca2+ in heart mitochondria.
A variety of experimental conditions were applied with the aim to estimate the correlation between the contribution of ATP synthase to the respiratory flux control and the calcium-induced activation of succinate oxidation in heart mitochondria isolated from rat, rabbit and guinea pig. The sensitivity of respiration in heart mitochondria to the decrease in temperature from 37 degrees C to 28 degrees C decreases in the order rabbit > guinea pig > rat. Ca2+ effect on succinate oxidation rate in state 3 respiration was species- and temperature-dependent and ranged from 0 (rat, 37 degrees C) to +44% (rabbit, 28 degrees C). For mitochondria from all experimental animals, the increase of Ca2+ in physiological range of concentration did not change state 2 respiration rate, and the stimulatory effect of Ca2+ on state 3 respiration was more pronounced at 28 degrees C than at 37 degrees C. The respiratory subsystem was sensitive to Ca2+ ions only in rabbit heart mitochondria. A high positive correlation between Ca2+ ability to stimulate succinate oxidation in state 3 and the control exerted by ATP synthase over the respiratory flux provides argument confirming stimulation of ATP synthase by Ca2+ ions.
Baniene
R
R
Institute for Biomedical Research, Kaunas University of Medicine, Eiveniu 4, LT-5009 Kaunas, Lithuania. bioch@kmu.lt
Nauciene
Z
Z
Maslauskaite
S
S
Baliutyte
G
G
Mildaziene
V
V
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D019069:Cell Respiration / Q000502:physiology*; D002478:Cells, Cultured; D003198:Computer Simulation; D004789:Enzyme Activation; D006168:Guinea Pigs; D008297:Male; D008657:Metabolic Clearance Rate; D008929:Mitochondria, Heart / Q000502:physiology*; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D008955:Models, Cardiovascular; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D013223:Statistics as Topic; D019802:Succinic Acid / Q000378:metabolism*
D019802:Succinic Acid; D025261:Mitochondrial Proton-Translocating ATPases; D002118:Calcium