Reduction of water permeability in potato tuber slices by cyanide, ammonia, 2,4-dinitrophenol, and oligomycin and its reverse by adenosine 5'-triphosphate and cytidine 5'-triphosphate.

Five millimolar KCN reduced water permeability in 1-millimeter thick slices of potato tuber (Solanum tuberosum L.). One-tenth millimolar ATP and CTP prevented or reversed the reduced permeability. UTP and GTP were not effective. Five millimolar ammonium carbonate or 0.1 millimolar 2,4-dinitrophenol also reduced water permeability, but ATP and CTP were only partially effective in reversing the reduced permeability. Oligomycin, 5 micrograms per milliliter, reduced water permeability, and the reduction was reversed by ATP and CTP. ATP and CTP appear to be involved in maintaining the structure of water pathways into the cell.