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 (RB C) membranes of eight species of marsupial were monitored by using a M n2+-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 parameter s characterizing the RBC water permeability the animals could be divid ed in two groups. 4. For the first group, including the large macropod id marsupials, eastern grey kangaroo (Macropus giganteus) and red kang aroo (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 ba ndicoot (Isoodon macrourus), bilby (Macrotis lagotis sagitta), Tasmani an 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 fr om 8.1-10.4 x 10(-3) cm/sec at 24.6-degrees-C; 8.9-11.8 x 10(-3) cm/se c 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 w ater permeability the RBC of the marsupials in the second group exhibi ted lower values of E(a,d) ranging from 15 21 kJ/mol, except for Goodf ellow's tree kangaroo, for which the E(a,d) was approximately 25 kJ/mo l.