Comparative NMR studies of diffusional water permeability of red blood cells from different species

The water diffusional permeability (Pd) of red blood cells (RBC) from agile wallaby (Macropus agilis), red-necked wallaby (Macropus rufogriseus) and Goodfellow's tree kangaroo (Dendrolagus goodfellowi) was monitored using an Mn2+-doping 1H nuclear magnetic resonance (NMR) technique at 400 MHz. The Pd (cm s− 1) values of agile wallaby RBCs were 7.5 × 10− 3 at 25 °C, 9 × 10− 3 at 30 °C, 11 × 10− 3 at 37 °C, and 13 × 10− 3 at 42 °C. The inhibitory effect of a mercury-containing sulfhydryl (SH)-modifying reagent p-chloromercuribenzoate (PCMB) on agile wallaby RBCs was investigated. The maximal inhibition was reached in 90 min at 37 °C with 2 mmol L− 1 PCMB. The value of maximal inhibition was ~ 63% when measured at 25 °C, ~ 52% at 37 °C and ~ 45% at 42 °C. The lowest value of Pd (corresponding to the basal permeability to water) was ~ 3 × 10− 3 cm s− 1 at 25 °C. For the RBCs from red-necked wallaby (M. rufogriseus) the values of Pd (cm s− 1) were 7 × 10− 3 at 25 °C, 8 × 10− 3 at 30 °C, 10 × 10− 3 at 37 °C, and 12 × 10− 3 at 42 °C. Higher values of Pd (cm s− 1) were found for the RBCs from Goodfellow's tree kangaroo (D. goodfellowi): 8.5 × 10− 3 at 25 °C, 10 × 10− 3 at 30 °C, 13 × 10− 3 at 37 °C, and 15 × 10− 3 at 42 °C. The mean values of the activation energy of water diffusion (Ea,d) were ~ 25 kJ mol− 1 for RBCs from the agile wallaby and tree kangaroo, respectively, and ~ 23 kJ mol− 1 for RBCs from red-necked wallaby. The values of Ea,d increased after exposure of agile wallaby RBCs to PCMB, reaching a value of ~ 43-46 kJ mol− 1 when the maximal inhibition of Pd was achieved.