Effects of p-chloromercuribenzene sulfonate on water transport across the marsupial erythrocyte membrane.
The effects of exposure of red blood cells (RBC) of three species of marsupial to a mercury-containing sulfhydryl-modifying reagent, p-chloromercuribenzene sulfonate (PCMBS), on the water diffusional permeability ( P (d)) of their membranes were monitored by using an Mn(2+)-doping (1)H nuclear magnetic resonance (NMR) technique at 400 MHz. For koala ( Phascolarctos cinereus), RBC the maximal inhibition was reached at 37 degrees C in 60 min with 1 mmol.l(-1) PCMBS or in 15-30 min with 2 mmol. l(-1) PCMBS. In contrast, in the case of red kangaroo ( Macropus rufus) or swamp wallaby ( Wallabia bicolor) RBC, maximal inhibition required an incubation of 90 min at 37 degrees C with 2 mmol.l(-1) PCMBS. For the RBC of all three species the value of maximal inhibition was very high, being 50-70% when measured at 25 degrees C, 60-80% at 30 degrees C and 60-70% at 37 degrees C. The lowest values of P (d) appeared to be around 2 x 10(-3)-3 x 10(-3) cm.s(-1) in the temperature range of 25-37 degrees C. The mean value of the activation energy of water diffusion ( E (a,d)) was approximately 20-25 kJ.mol(-1) for control and approximately 40 kJ.mol(-1) for PCMBS-inhibited RBCs. These results show that marsupial RBC have a basal permeability to water similar to that previously reported for human RBC, but a higher value of the PCMBS-inhibitable water permeability. This indicates that the higher water permeability of marsupial RBC compared with human RBC is associated with a higher fraction of protein-mediated water permeability.
Department of Cell and Molecular Biology, "Iuliu Hatieganu" University of Medicine Cluj-Napoca, 3400 Cluj-Napoca, Romania. GBenga@personal.ro
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Benga
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Chapman
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Matei
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Gallagher
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Blyde
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Kuchel
D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D004058:Diffusion; D004910:Erythrocyte Membrane / Q000378:metabolism*; D007614:Macropodidae; D008394:Marsupialia / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*
D013439:Sulfhydryl Reagents; D014867:Water; D002731:4-Chloromercuribenzenesulfonate