Some aspects of zinc transport across eel (Anguilla anguilla) red blood cell membranes.

Zinc movement across eel and human red blood cell membranes was measured by atomic absorption spectrophotometry. It was observed that: 1) In human red blood cells zinc uptake is twice as rapid as in fish red blood cells over a temperature range of 10-40 degrees C. The low rate of zinc uptake in eel red blood cell may be simply the side effect of different surface area to volume ratios for the differences in cell size or, it may be due to the low permeability of bicarbonate through the red blood cell membranes. 2) Zinc uptake measured in eel and human red blood cells treated and untreated with external trypsin shows different features. The zinc uptake was reduced by about 40% in treated eel red blood cells with respect to the total uptake of untreated red blood cells. Human red blood cells treated and untreated with trypsin do not show any differences in the amount of zinc transported. 3) In fish red blood cells, zinc uptake in NaNO3 medium is markedly reduced, compared with that measured in NaCl medium. The [Zn2+i slightly increases in the presence of bicarbonate. In human red blood cells in NaNO3 medium the zinc uptake is strongly reduced and the presence of bicarbonate marginally increases the zinc influx. 4) In eel red blood cells there seem to be two independent pathways for zinc uptake: one DIDS-sensitive and the other DIDS-insensitive. DIDS 10 microM inhibits only 64% of the total zinc transported. Increasing the DIDS concentration did not give more inhibition. In human red blood cells only one DIDS-sensitive pathway for zinc transported seems to exist, because, 2, 5 microM DIDS inhibits 97% of zinc uptake.