THE GENERATION OF LATENT-ION-TRANSPORT CAPACITY

Abstract

Slices 9 mm in diameter of potato tuber were used and in most experiments, were aged 22 to 24 hours in 3 changes of 10-3 [image] CaSO4. HCl36 with a specific activity of 0.586 mc/g Cl was used. Under selected conditions metabolic activity occurring at one time, can produce a unit of ion-absorbing capacity which can be manifested later. The absorption of chloride ion at 0[degree]C by potato disks transferred from 30[degree]C proceeds in 2 stages. The initial stage of rapid uptake, which has been termed the "absorption shoulder", lasts approximately 1 hour, and is taken to reflect absorption capacity generated at the higher temperature. At any time after the 1st stage has been completed, a new shoulder can be created by transferring the tissue to 30[degree]C for as little as 5 minutes. The original shoulder can be dissipated by an hour''s preincubation in H2O at 0[degree]C. Diphosphopyri-dine nucleotide inhibits both steady-state uptake and the generation of a new shoulder. Cyanide affects neither, but wipes away the original shoulder when presented simultaneously with chloride at 0[degree]C.