Further studies on the roles of sodium and potassium in the generation of the electro-olfactogram. Effects of mono- , di- , and trivalent cations.

In the negative EOG-generating process a cation which can substitute for Na(+) was sought among the monovalent ions, Li(+), Rb(+), Cs(+), NH(4) (+), and TEA(+), the divalent ions, Mg(++), Ca(++), Sr(++), Ba(++), Zn(++), Cd(++), Mn(++), Co(++), and Ni(++), and the trivalent ions, Al(+++) and Fe(+++). In Ringer solutions in which Na(+) was replaced by one of these cations the negative EOG's decreased in amplitude and could not maintain the original amplitudes. In K(+)-Ringer solution in which Na(+) was replaced by K(+), the negative EOG's reversed their polarity. Recovery of these reversed potentials was examined in modified Ringer solutions in which Na(+) was replaced by one of the above cations. Complete recovery was found only in the normal Ringer solution. Thus, it was clarified that Na(+) plays an irreplaceable role in the generation of the negative EOG's. The sieve hypothesis which was valid for the positive EOG-generating membrane or IPSP was not found applicable in any form to the negative EOG-generating membrane. The reversal of the negative EOG's found in K(+)- , Rb(+)- , and Ba(++)-Ringer solutions was attributed to the exit of the internal K(+). It is, however, not known whether or not Cl(-) permeability increases in these Na(+)-free solutions and contributes to the generation of the reversed EOG's.