COMPARATIVE NUCLEAR-MAGNETIC-RESONANCE STUDIES OF DIFFUSIONAL WATER PERMEABILITY OF RED-BLOOD-CELLS FROM DIFFERENT SPECIES .8. ADULT AND FETAL GUINEA-PIG (CAVIA-PROCELLUS)

The diffusional water permeability (P-d) of adult, pregnant female and fetal guinea-pig red blood cells (RBCs) was measured by a doping nuclear magnetic tic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulphonate (PCMBS). The values of P-d were around 5.0 x 10(-3) cm/s at 15 degrees C, 5.3 x 10(-3) cm/s at 20 degrees C, 6.6 x 10(-3) cm/s at 25 degrees C, 7.5 x 10(-3) cm/s at 30 degrees C and 8.6 x 10(-3) cm/s at 37 degrees C with no significant differences between adult, pregnant female and fetal RBCs. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 10 min at 37 degrees C with 0.1 mM PCMBS. The values of maximal inhibition ranged from 70%-77% at 15-30 degrees C to 57%-63% at 37 degrees C in the case of adult and from 64%-67% at 15-30 degrees C to 51% at 37 degrees C in the case of fetal RBCs. The basal permeability to water was estimated at 1.1 x 10(-3) cm/s at 15 degrees C, 1.3 x 10(-3) cm/s at 20 degrees C, 1.6 x 10(-3) cm/s at 25 degrees C, 2.2 x 10(-3) cm/s at 30 degrees C and 3.2 x 10(-3) cm/s at 37 degrees C for adult and slightly higher values for fetal guinea pig RBCs as 1.6 x 10(-3) cm/s at 15 degrees C, 2.0 x 10(-3) cm/s at 20 degrees C, 2.4 x 10(-3) cm/s at 25 degrees C, 2.6 x 10(-3) cm/s at 30 degrees C and 4.2 x 10(-3) cm/s at 37 degrees C. The activation energy of water diffusion was around 22 kJ/mol, with no significant differences between the-adult pregnant female and fetal RBCs, and increased to about 40 kJ/mol in the case of adult and pregnant RBCs and 34 kJ/mol for fetal RBCs after incubation with PCMBS in conditions of maximal inhibition of water diffusion. The membrane polypeptide electrophoretic pattern of adult and fetal guinea-pig RBCs was compared with its human counterpart. The guinea-pig membrane contained higher amounts of spectrin (band 1 and 2), whereas the proteins in bands 4.1, 4.2 and 6 were present in lower amounts. Considerable differences in polypeptides migrating in the region of bands 7 and 8 and in front of them were apparent between the two sources of RBC membranes where some bands were present only in the guinea-pig RBC membranes. The adult guinea-pig membranes contained smaller amounts of proteins migrating in band 4.5 and lacked band 8.