Endlicher 2017 MiP2017
Calcium is the most important element in cellular signaling. In the cells calcium ions are present especially in the endoplasmic reticulum and mitochondria. Although mitochondria are not the primary calcium-storage organelles, they are very important in modulating Ca2+ signal within the cells. In mitochondria, calcium ions regulate mitochondrial permeability transition pore (MPTP). Increased concentration of Ca2+, inorganic phosphate and oxidative stress, causes opening of MPTP and consequently can lead to cell death induction. Literature data have shown that the sensitivity of mitochondria to Ca2+ ions changes during ontogenesis. The goal of our work was to monitor age-related changes in Ca2+ ion effect on MPTP and the ability of mitochondria to accumulate calcium. We also measured changes in mitochondrial membrane potential (MMP) and mitochondrial respiration in selected groups.
All experiments were performed on adult male Wistar rats with body weight 200 - 500 g (age of 7 - 15 weeks). Liver mitochondria were isolated by differential centrifugation. The sensitivity of isolated mitochondria to calcium ions was evaluated by measurement of mitochondrial swelling and calcium retention capacity in mitochondria. Mitochondrial swelling was estimated from the decrease in the absorbance at 520 nm (Shimadzu UV-1601). Changes of mitochondrial retention capacity for calcium were assessed using the fluorescent probe - Calcium Green (AMINCO-Bowman Series 2). Changes of MMP were determined using a Safranin O fluorescent probe (AMINCO-Bowman Series 2). Oxygen consumption was measured by high-resolution respirometry using a an O2k-FluoRespirometer (Oroboros Instruments).
The mitochondrial retention capacity for calcium is significantly affected by the age of the rat. We proved that mitochondria isolated from livers of older rats showed a lower retention capacity for calcium. A significant decrease in retention capacity was observed with a weight gain of 200 g to 300 g. Rats weighing 300 g showed only 80% retention capacity versus 200 g rats (p<0.01). The retention capacity is further decreased with increasing weight of rats. The rate of mitochondrial swelling is dependent on the concentration of Ca2+ in the incubation medium. We have shown that liver mitochondria isolated from older rats respond to the same concentration of Ca2+ by higher degree of swelling. We did not observe changes in MMP and respiration in rats of different weights. In conclusion, liver mitochondria isolated from older rats showed increased sensitivity to calcium ions.
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style Pathology: Aging;senescence
Organism: Rat Tissue;cell: Liver Preparation: Isolated mitochondria
Affiliations and support
- Endlicher R(1,2), Drahota Z(1,3), Staňková P(1), Kučera O(1), Červinková Z(1)
- Dept Physiol, Fac Medicine Hradec Králové, Charles Univ
- Dept Anatomy, Fac Medicine Hradec Králové, Charles Univ
- Inst Physiol, Acad Sciences Czech Republic; Czech Republic, Prague. - [email protected]
- This work was supported by research program: PROGRES Q40/02 and Inter-Cost LTC17044.