FIG. 5.
Cadaverine induces a sustained inhibition of porins. Cephaloridine flux rates were obtained from wild-type strain W3110 containing the R471a factor. The following treatments were carried out in parallel for each batch of cells: (i) cells were incubated in permeability buffer in the presence (black) or absence (white) of 100 mM cadaverine for the times indicated and assayed immediately thereafter in the same solution; and (ii) cells were incubated in permeability buffer in the presence (horizontal stripes) or the absence (hatched) of 100 mM external cadaverine for the times indicated, spun down, resuspended in permeability buffer only, and assayed in permeability buffer only. Values are the averages of four experiments (triplicate measurements per experiment), and error bars represent SEM.