GLYCEROL PERMEABILITY OF RYE LEAF PROTOPLASTS AS AFFECTED BY TEMPERATURE AND ELECTROPORATION

The permeability of rye leaf protoplasts to glycerol was determined us ing 1,3-C-14 glycerol and liquid scintillation spectrometry. Estimates were 1.0 x 10(-8) m s(-1) at 0 degrees C and 4.1 x 10(-8) m s(-1) at 22 and 31 degrees C. The activation energy for glycerol permeability w as 32.8 kJ/mol. The effect of electroporation on glycerol uptake was a lso explored. Treatments were performed with a field strength of 100 V /cm and an exponential decay constant of 5.8 ms. At 22 degrees C, elec troporation affected the rate and extent of glycerol permeation, causi ng an increase in the intercept of the glycerol uptake curve and a dec rease in the slope. Electroporation had no significant effect on glyce rol uptake when performed at 0 degrees C, when the cells were electrop orated at 0 degrees C then warmed to 31 degrees C, or when the cells w ere electroporated at 22 degrees C then cooled to 0 degrees C. The res ults at 22 degrees C were consistent with an influx of glycerol during electroporation.