NMR studies of diffusional water permeability of red blood cells from the echidna Tachyglossus aculeatus

• Published in: Comparative biochemistry and physiology. B, Comparative biochemistry Vol. 107; no. 1; pp. 45 - 50
• Main Authors: Benga, Gheorghe, Ralston, Gregory B, Borza, Tudor, Chapman, Bogdan E, Gallagher, Clifford H, Kuchel, Philip W
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1994
• Subjects: Diffusional water permeability; NMR; Red blood cells; Tachyglossus aculeatus; Diffusional water permeability; NMR; Red blood cells; Tachyglossus aculeatus
• ISSN: 0305-0491
• DOI: 10.1016/0305-0491(94)90223-2

The diffusional water permeability (P d) of the red blood cells (RBC) from echidna ( Tachyglossus aculeatus) was measured by a Mn 2+-doping 1H nuclear magnetic resonance (NMR) technique at 400 MHz. The values of P d were relatively low: around 1.9 × 10 −3 cm/sec at 25°C, 2.2 × 10 −3 cm/sec at 29.5°C, 2.9 × 10 −3 cm/sec at 35.2°C, 3.2 × 10 −3 cm/sec at 37°C, 3.9 × 10 −3 cm/sec at 40.5°C and 4.2 × 10 −3 cm/sec at 42°C. In parallel with the low water permeability the activation energy for the diffusion process (E a,d) was relatively high, ∼ 33 kJ/mol. The membrane polypeptide electrophoretic pattern of echidna RBC was compared with its human counterpart. The proteins migrating in bands 3 and 4.1 had lower mobilities in echidna compared with human membranes. In the echidna RBC membranes band 4.1 was not split into 4.1a and 4.1b sub-bands. Glyceraldehyde 3-phosphate dehydrogenase (band 6) was markedly less intense in echidna than in human RBC. The faint bands between 4.2 and 5 and in the band 7–8 region showed considerable differences between the two species. At low ionic strength the pattern of solubilization of proteins from echidna RBC membranes was different from human membranes, with only a trace of band 4.1 protein extracted from the echidna RBC.