Effect of tetraethylammonium ions and 4-aminopyridine on osmotic stability of Saccharomyces cerevisiae

Tetraethylammonium bromide (TEA) and 4-aminopyridine (4-AP) are lethal to Saccharomyces cerevisiae, However, the growth of yeast cells is restored on addition of osmotic stabilizers, i.e. 0.2 M KCl, 0.2 M NaCl or 0.4 M mannitol, to the plates containing inhibitory concentration of TEA and 4-AP, 4-AP induces osmotic stability defects instead of blocking K+ channels in S. cerevisiae as reported in animal cells, As a result, this drug causes cell lysis whereas TEA seems to cause lethality by bringing about some other changes in the plasma membrane of the yeast cells.