Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. XII. Dog (Canis familiaris) and cat (Felis domestica)

The diffusional water permeability (Pd) of dog and cat 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 sulphonate (PCMBS). The values of Pd were in the case of cat RBC ∼3.0 × 10-3 cm/s at 15 °C, 3.5 × 10-3 cm/s at 20 °C, 4.2 × 10-3 cm/s at 25 °C, 4.4 × 10-3 cm/s at 30 °C and 5.9 × 10-3 cm/s at 38 °C. In case of dog RBC the values of Pd were higher ∼3.8 × 10-3 cm/s at 15 °C, 4.6 × 10-3 cm/s at 20 °C, 5.0 × 10-3 cm/s at 25 °C, 5.9 × 10-3 cm/s at 30 °C and 7.9 × 10-3 cm/s at 37 °C. Systematic studies of the effect of PCMBS on water diffusion indicated that in the case of dog RBCs the maximal inhibition was reached in 15-30 min with 1 mM PCMBS, whereas in the case of cat RBCs in 60 min with 1 mM PCMBS or in 30 min with 2 mM PCMBS. The values of maximal inhibition in the case of cat RBC were in the range of 55-60% at 15 °C, 60-68% at 20 °C and 25 °C, 50-60% at 30 °C and 50-55% at 37 °C. In the case of dog RBC the corresponding values were higher, 75-80% at 15 °C, 70-80% at 20 °C and 25 °C, 65-70% at 30 °C and 55-60% at 37 °C. The basal permeability to water was estimated to be ∼1 × 10-3 cm/s -2 × 10-3 cm/s in the range of temperatures of 25-37 °C. The activation energy of water diffusion Ea,d was ∼19 kJ/mol for the dog RBC and ∼23 kJ/mol for the cat RBC. After incubation with PCMBS the values of Ea,d increased, reaching 40 kJ/mol in conditions of maximal inhibition of water exchange. The membrane polypeptide electrophoretic pattern of dog and cat RBCs has been compared with its human counterpart. Dog and cat RBCs contained higher amounts of spectrin (band 1 and 2) and lower amounts of bands 4.4, 4.2, band 5 and band 7 compared to human RBCs. Band 4.9 was decreased only in the cat RBCs, whereas band 6 was decreased only in the dog RBCs.