Dimethylsulfoxide as a potential tool for analysis of compartmentation in living plant cells

Data are presented which indicate that dimethylsulfoxide (DMSO) acts selectively on the plasma membrane of cultured tobacco cells, rendering it more permeable to small molecules, while having a far smaller effect on the permeability of the vacuolar membrane. The results which support this conclusion are: (a) DMSO (5 to 10%, by volume) causes complete release of [(14)C]tryptophan newly synthesized from [(14)C]indole while causing efflux of only about 20% of the total intracellular tryptophan pool; (b) similar concentrations of DMSO do not cause substantial release from these cells of phenolic compounds or preloaded neutral red, nor of beta-cyanin from fresh beet discs; (c) kinetic studies of release of tryptophan and neutral sugars and of efflux of (86)Rb(+) show that DMSO selectively promotes rapid release of a portion of the total pool, followed by a substantially slower release of the remaining pool; (d) when tobacco cell protoplasts are incubated in the presence of 7.5% (by volume) DMSO, rapid lysis is observed concomitant with the release of intact vacuoles. These data indicate that a procedure involving a brief treatment of intact plant cells or tissues with DMSO may be used to assess the distribution of metabolites between cytoplasmic and vacuolar compartments.