Ionic Permeabilities of Different Isolated Fruit Cuticles Calculated by Conductivity and Membrane Potential Measurements

A. Muñoz and A. Heredia Departamento de Bioquimica y Biologfa Molecular, Facultad de Ciencias, Universidad de Malaga, E-29071 Malaga, Spain Z. Naturforsch. 49c, 615-618 (1994); received May 9/June 8, 1994 Fruit Cuticles, Membrane Potential, Membrane Conductivity, Ionic Permeabilities Membrane potential and electrical resistance for two isolated fruit cuticular membranes (tomato and pepper cuticles) were measured for different NaCl solutions (10-3 m < C < 5 x l 0 ~ 2 m). From these experimental results some membrane characteristic parameters were obtained such as cation transport number, t+, which represents the fraction of the electric current transported by the cation, / + , with respect to the total current, / x ( t+ = / + / / t ) , and ionic permeabilities. P + and P_, for both membranes. Concentration dependence of these parameters was also considered. A comparative study between both types of fruit cuticles is also made. It was found that cation transport number, ionic permeabilities and electrical resistances are quite similar for both membranes.