Molecular Pharmacology, Vol 11, 185-189, Copyright © 1975 by the American Society for Pharmacology and Experimental Therapeutics

Reduction of Rat Liver Microsomal Ribonuclease by Cycloheximide

¹ Department of Pharmacology and Toxicology, University of Maryland School of Pharmacy, Baltimore, Maryland 21201

An inhibitor of mRNA translation, cycloheximide, reduced RNA degradation by hepatic microsomal ribonuclease in a dose-related manner. This decrease occurred prior to a measurable reduction in microsomal protein or oxidative demethylation activity. Graphical analysis of the time plot of ribonuclease activity decay following cycloheximide administration indicated that the half-life of the microsomal ribonuclease was 54 min. The reduction of ribonuclease activity by this inhibitor was not attributable to its direct effects, nor was the presence of the adrenal glands necessary. The results indicate that the short onset of microsomal RNase reduction produced by cycloheximide may be due to a more rapid turnover of this enzyme in comparison with other microsomal proteins.

Note:
ACKNOWLEDGMENT The technical assistance of Mr. Joseph H. Lewis, Jr., is acknowledged.