ELECTRIC ASYMMETRY OF TOMATO CUTICULAR MEMBRANES FROM PERMSELECTIVITY AND RESISTANCE VALUES

Membrane potentials (DELTAphi) and electrical resistance (R) of isolated tomato cuticular membranes were measured for different NaCl solutions. From membrane Potential values, the membrane permselectivity (P(s)) was calculated. A strong decrease of both P(s) and R values when the concentration increases was obtained. Differences in permselectivity values for similar but reversed external conditions, as well as those found for the resistance when the polarity of the electric current is reversed are indicated, and they are attributed to the asymmetry of the cuticular membranes. A comparison of these results with those found for a composite artificial membrane has also been made.