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 resonan ce (NMR) technique on control cells and following inhibition with p-ch loromercuribenzene sulfonate (PCMBS). 2. The values of P(d) were aroun d 6.3 x 10(-3) cm/sec at 15-degrees-C, 7.0 x 10(-3) cm/sec at 20-degre es-C, 8.0 x 10(-3) cm/sec at 25-degrees-C, 9.1 x 10(-3) cm/sec at 30-d egrees-C and 10.7 x 10(-3) cm/sec at 37-degrees-C. 3. Systematic studi es on the effects of PCMBS on water diffusion indicated that the maxim al 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 temper atures. 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, an d 3.1 x 10(-3) cm/sec at 37-degrees-C. 6. The activation energy of wat er diffusion was around 18 kJ/mol and increased to 27 kcal/mol after i ncubation with PCMBS in conditions of maximal inhibition of water diff usion. 7. The membrane polypeptide electrophoretic pattern of rabbit R BCs has been compared with its human counterpart. 8. The rabbit membra ne contained a higher amount of spectrin (bands 1 and 2), while the ba nd 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less inte nse. 9. Considerable differences in the electrophoretic patterns of th e 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 a pparent in higher amounts in the rabbit RBC membrane.