COMPARATIVE NUCLEAR-MAGNETIC-RESONANCE STUDIES OF DIFFUSIONAL WATER PERMEABILITY OF RED-BLOOD-CELLS FROM DIFFERENT SPECIES .5. RABBIT (ORYCTOLAGUS-CUNICULUS)

1. The diffusional water permeability (P(d)) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS). 2. The values of P(d) were around 6.3 x 10(-3) cm/sec at 15-degrees-C, 7.0 x 10(-3) cm/sec at 20-degrees-C, 8.0 x 10(-3) cm/sec at 25-degrees-C, 9.1 x 10(-3) cm/sec at 30-degrees-C and 10.7 x 10(-3) cm/sec at 37-degrees-C. 3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37-degrees-C with 0.5 mM PCM BS. 4. The values of maximal inhibition were around 71-74% at all temperatures. 5. The basal permeability to water was estimated as 1.6 x 10(-3) cm/sec at 15-degrees-C, 2.0 x 10(-3) cm/sec at 20-degrees-C, 2.4 x 10(-3) cm/sec at 25-degrees-C, 2.6 x 10(-3) cm/sec at 30-degrees-C, and 3.1 x 10(-3) cm/sec at 37-degrees-C. 6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion. 7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart. 8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense. 9. Considerable differences in the electrophoretic patterns of the two sources of RBC membranes appeared in the bands migrating in the band 4.5 region and in front of band 7, where some polypeptides were apparent in higher amounts in the rabbit RBC membrane.