Action of monovalent cations on the biological properties of PR toxin, a mycotoxin from Penicillium roqueforti.

PR toxin impairs liver cell metabolism by inhibiting RNA and protein synthesis. In vitro, the drug inhibits the transcription carried out by isolated rat liver nuclei and the translation promoted by polysomes. The action of monovalent cations on the biological activities of PR toxin has been studied. The increased ionic strength due to the presence of salt in the incubation medium, lowers the inhibitory action of PR toxin on in vitro transcription and translation activities; this action is reversible. Besides the overall effect of the ionic strength, ammonium salts possess a specific ability to suppress irreversibly the biological properties of PR toxin (in vivo toxicity and capacity of inhibiting RNA and protein synthesis). The mechanism of this action is discussed.