[The ionic selectivity of the membrane mechanisms for potassium transport in the neurons of Planorbarius corneus mollusks].

The in- and outflow of 204Tl, 86Rb and 137Cs in a snail brain was studied. The inward rate constants determined in the presence and without ouabain decreased as follows: Tl+ greater than Rb+ greater than Cs+. The inflow rate constants differed about 2-3 fold.