Effect of light on resting potential and activity of H+, K+, Na+ cations in the vacuole juice of Nitella cellsстатья
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Дата последнего поиска статьи во внешних источниках: 28 мая 2015 г.
Аннотация:Activities of K+, Na+, and H+ in the vacuolar sap of internodal Nitella flexilis cells were measured by means of ion-specific microelectrodes under periodic white light illumination (tungsten lamp, 5000 lx, 5 to 7 min light and dark intervals). The determination of cation activity was made simultaneously with the registration of the resting potential (RP). It was shown that the pH values of the vacuolar sap lay in the region from 4 to 5 units and depended on the conditions of illumination. Illumination was followed by cell depolarization and by a shift of the sap pH-values toward the acid side of the scale. RP and pH values acquired their initial values when the light was switched off. K+ and Na+ activities of the sap (95 +/-12 mM and 14 +/-2.4 mM, respectively) did not change under illumination. Possible mechanisms of photoinduced changes of RP are discussed. It is pointed out that these changes may be determined by the rate of electrogeneous influx of H+ into the cell vacuole.