Age-Dependent Brain Tissue Hydration, Ca Exchange and their Dose- Dependent Ouabain Sensitivity
Sinerik Ayrapetyan*, Armenuhi Heqimyan and Anna Nikoghosyan
UNESCO Chair-Life Sciences, International Postgraduate Educational Center, 31 Acharyan St, 0040 Yerevan, Armenia
- *Corresponding Author:
- Sinerik Ayrapetyan
UNESCO Chair-Life Sciences International Postgraduate Educational
Center, 31 Acharyan St, 0040 Yerevan, Armenia
E-mail: [email protected]
Received Date: May 04, 2012; Accepted Date: May 26, 2012; Published Date: May 28, 2012
Citation: Ayrapetyan S, Heqimyan A, Nikoghosyan A (2012) Age-Dependent Brain Tissue Hydration, Ca Exchange and their Dose-Dependent Ouabain Sensitivity. J Bioequiv Availab 4: 060-068. doi: 10.4172/jbb.10000114
Copyright: © 2012 Ayrapetyan S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Tissue hydration, dose-dependent 3H-ouabain binding, 45Ca2+ exchange in ratÃ¯Â¿Â½s brain cortex, subcortex and cerebellum were studied in three age groups. Age-dependent tissue dehydration in all three zones of brain was due to inhibition of Na+/K+ pump. The age-dependence of cell hydration in cortex was more expressed. The curve of dose-dependent ouabain binding consists of three components corresponding to Na+/K+ pump isoforms (α1, α2, α3). Age-dependency of these isoforms was more expressed in cortex than in subcortex and cerebellum. High affinity receptors were depressed in old ratsÃ¯Â¿Â½ brain tissues. Initial 45Ca2+ uptake in three brain zones of old rats was depressed as compared to that of young animals. Ouabain at 10-9 M has activation effect on 45Ca2+ uptake, which was also age dependent. Initial 45Ca2+ efflux in cortex and subcortex tissue in old rats was significantly depressed as compared to young ones while in cerebellum the opposite age-dependence was observed. The curves of dose-dependent ouabain effect on 45Ca2+ efflux and cell hydration consist of 6 components. However, close correlation between kinetics of 45Ca2+ efflux and cell hydration was not observed. It is suggested that brain tissue dehydration in aged animals is a consequence of Na+/K+ pump dysfunction induced intracellular calcium elevation. It is suggested that α3 receptors are functionally connected with intracellular Ca2+ buffering systems through intracellular signaling systems and their dysfunction in aged brain is a consequence of [Ca2+]i increase. Obtained data allow us to conclude that endogen nanomolar ouabain-like species circulating in mammalsÃ¯Â¿Â½ blood removing Ca2+ from cells could have a beneficial effect on brain of old animals.