NMR Studies of Diffusional Water Permeability of Erythrocytes from Eight Species of Marsupial
Gheorghe Benga2, Bogdan E. Chapman1, Clifford H. Gallagher1,4, Nihal S. Agar3, Philip W. Kuchel1
1Department of Biochemistry, University of Sydney, Sydney, NSW 2006, Australia (Fax 61-2-692-4726)
2Department of Cell and Molecular Biology, University of Medicine and Pharmacy, Cluj-Napoca, 340 Cluj-Napoca, Romania
3Department of Physiology, University of New England, Armidale, NSW 2351, Australia
4Taronga Zoo, PO Box 20, Mosman, NSW 2088, Australia
1. The diffusional water permeability (Pd) of the red blood ceil (RBC) membranes of eight species of marsupial were monitored by using a Mn2+-doping 1H nuclear magnetic resonance (NMR) technique at 400 MHz (9.4T).
2. There were differences in the water permeability of the RBC membranes among the species investigated.
3. On the basis of parameters characterizing the RBC water permeability the animals could be divided in two groups.
4. For the first group, including the large macropodid marsupials, eastern grey kangaroo (Macropus giganteus) and red kangaroo (M. rufus), the values of Pd were 5.4-6.1 x 10-3cm/sec at 24.6°C; 6.6-7.2 x 10-3cm/sec at 30°C; 7.8-9.1 x 10-3cm/sec at 37°C and 9.3-11.1 x 10-3cm/sec at 42.1°C.
5. The values of the activation energy for the diffusion process (Ea,d) ranged from 24-27 kJ/moI.
6. For the second group, including bandicoot (Isoodon macrourus), bilby (Macrotis lagotis sagitta), Tasmanian devil (Sarcophilus harrisii), koala (Phascolarctis cinereus), brush tailed possum (Trichosurus vulpecula), and Goodfellow’s tree kangaroo (Dendrolagus goodfellowi), the values of Pd were higher, ranging from 8.1-10.4 x 10-3cm/sec at 24.6°C; 8.9-11.8 x 10-3cm/sec at 30°C; 10.3-13.7 x 10-3cm/sec at 37°C and 11.9-15.3 x 10-3cm/sec at 42.1°C.
7. In parallel with the high water permeability the RBC of the marsupials in the second group exhibited lower values of Ea,d ranging from 15-2I kJ/mol, except for Goodfellow’s tree kangaroo, for which the Ea,d was ~25 kJ/mol.