| Abstract: | The state of adenylate system and intensity of oxidative phosphorylation in liver mitochondria of active and hibernating ground squirrels were studied depending on the concentration of extramitochondrial Ca2+ (Ca2+]ex). It was shown that at Ca2+]ex.10(-7) M, the content of ATP as well as ATP/ADP ratio are slightly lower in the mitochondria of hibernating ground squirrels than in the mitochondria of active animals. The other parameters of the adenylate system under the same conditions differ insignificantly. Ca2+]ex increase to 10(-6) M has little effect on the parameters of the adenylate system of active animals. On the contrary, the mitochondria of hibernating ground squirrels are strongly affected: the level of ATP is 1.5-fold and the ratio of ATP/ADP is almost 2-fold decreased. At both Ca2+]ex the intensity of oxidative phosphorylation is essentially higher in the mitochondria of active ground squirrels. With increasing Ca2+]ex the rate of ATP synthesis decreases, and in the mitochondria of hibernating animals the decrease is more pronounced than in the mitochondria of active animals. Thus, oxidative phosphorylation and adenylate system of mitochondria from hibernating ground squirrels are more sensitive to Ca2+]ex increase than those of the mitochondria of active animals. |
