NMR-STUDIES OF DIFFUSIONAL WATER PERMEABILITY OF ERYTHROCYTES FROM 8 SPECIES OF MARSUPIAL

1. The diffusional water permeability (P(d)) of the red blood cell (RBC) membranes of eight species of marsupial were monitored by using a Mn2+-doping H-1 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 P(d) were 5.4-6.1 x 10(-3) cm/sec at 24.6-degrees-C; 6.6-7.2 x 10(-3) cm/sec at 30-degrees-C; 7.8-9.1 x 10(-3) cm/sec at 37-degrees-C and 9.3-11.1 x 10(-3) cm/sec at 42.1-degrees-C. 5. The values of the activation energy for the diffusion process (E(a,d)) ranged from 24 27 kJ/mol. 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 P(d) were higher, ranging from 8.1-10.4 x 10(-3) cm/sec at 24.6-degrees-C; 8.9-11.8 x 10(-3) cm/sec at 30-degrees-C; 10.3-13.7 x 10(-3) cm/sec at 37-degrees-C and 11.9-15.3 x 10(-3) cm/sec at 42.1-degrees-C. 7. In parallel with the high water permeability the RBC of the marsupials in the second group exhibited lower values of E(a,d) ranging from 15 21 kJ/mol, except for Goodfellow's tree kangaroo, for which the E(a,d) was approximately 25 kJ/mol.