Effect of temperature and of cytochalasin B and persantin on the nonmediated permeation of non-electrolytes into cultured Novikoff rat hepatoma cells.
The nonmediated permeation of L-glucose, cytosine, and prednisolone into Novikoff rat hepatoma cells followed first order kinetics with rate constants of 0.00404, 0.173, and 2.4 min-1, respectively. The constants were estimated from a nonlinear least squares fit of the integrated first order rate equation. The rate constants were independent of substrate concentration and correlated with the partition coefficients of the substances in octanol-balanced salt solution (0.00158, 0.0352, and 17.8, respectively) and olive oil-balanced salt solution mixtures which were between 10- and 100-fold lower. Arrhenius plots for the permeation of L-glucose, cytosine, and prednisolone were linear and indicated activation energies of 24.2, 28.0, and 19.6 kcal/mol, respectively. The permeation of L-glucose and cytosine, but not of prednisolone, was impeded in a concentration-dependent manner by the presence of cytochalasin B and Persantin, heretofore thought of as specific inhibitors of facilitated diffusion processes. The relative degree of decrease of the permeation rates of L-glucose and cytosine, however, differed for cytochalasin B and Persantin.
D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D003571:Cytochalasin B / Q000494:pharmacology*; D003596:Cytosine / Q000378:metabolism*; D004058:Diffusion; D004176:Dipyridamole / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D011239:Prednisolone / Q000378:metabolism*
D003571:Cytochalasin B; D004176:Dipyridamole; D003596:Cytosine; D011239:Prednisolone; D005947:Glucose