Determination of transport constants of isolated Nitella cell walls

• Published in: Canadian Journal of Botany
• Main Author: Tyree, M. T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1968
• Subjects: Plant Science; Nitella flexilis
• Online Access: http://dx.doi.org/10.1139/b68-054; http://www.nrcresearchpress.com/doi/pdf/10.1139/b68-054

Transport coefficients L PP , L PE , L EP , and L EE for electrokinetic equations according to irreversible thermodynamics, the Onsager coefficients, were measured for isolated Nitella flexilis cell walls in KCl solutions ranging from 10 −4 to 10 0 normal. L PP and L PE (= L EP ) were found to be independent of KCl concentration and equal to 1.4 × 10 −6 cm 3 sec −1 cm −2 (joule cm −3 ) −1 cm and 6 × 10 −5 cm 3 sec −1 cm −2 volt −1 cm respectively. L EE was a function of the salt concentration, reaching a limiting value of about 1.2 × 10 −3 mho cm −1 in 10 −4 N KCl. The activation energy for movement of KCl in cell walls was found to be 4.33 Kcal mole −1 the diffusion coefficient for KCl in cell walls was calculated by two methods to be 8 × 10 −6 cm 2 sec −1 and the concentration of the fixed ions in Nitella cell walls from the above data was estimated at greater than 0.04 equivalent per liter of cell wall. Electroosmosis in Nitella membranes is re-examined in the light of the measured transport coefficients and it is concluded that under proper conditions the cell wall of Nitella can contribute significantly (~20% or more) to the observed electroosmosis of living Nitella cells.