Potassium Transport Across the Membranes of Chara: III. EFFECTS OF pH, INHIBITORS AND ILLUMINATION |
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Authors: | SMITH, J. R. WALKER, N. A. SMITH, F. A. |
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Abstract: | Smith, J. R., Walker, N. A. and Smith, F. A. 1987. Potassiumtransport across the membranes of Chara. III. Effects of pH,inhibitors and illumination.J. exp. Bot. 38: 778787. The effects of several treatments, normally used to inhibitelectrogenic proton transport, upon the potassium permeability(Pk) of the membranes of Chara were examined by means of simultaneousmeasurements of the 42K influx ( inK) and the membrane electricalconductance (Gm). inK, PK and Gmwere found to be substantiallyunaffected when the external pH (pH?) was varied over the range5?0 to 85. However, when pH? was increased to 11 it was foundthat, although Gm increased considerably, both Pk and inK decreasedtypically by an order of magnitude. When cells were placed intotal darkness, PK decreased substantially only after one dayhad elapsed. For the particular experimental conditions used,the inhibitors DES, NaN3, and La3+ were found to alter PK, whereasDCCD left PK substantially unaffected. These results suggestthat care must be taken with some common procedures used toexamine the electrical properties of the electrogenic protonpump. Key words: Potassium, pH, illumination, inhibitors |
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