[Effect of cycloheximide on lysosomal proteinase activity in rat organs]

Administration of cycloheximide (0.1-0.4 mg/kg bw) to rats caused a progressive drop of cathepsin A, B, C and D activity in the liver and kidneys. In the spleen, the activity of all lysosomal proteinases declined 50-70% even with the minimal dose of cycloheximide. On the contrary, the activity of other lysosomal hydroxylases (beta-galactosidase and arylsulfatases A and B) dropped by not more than 10-25% in all the organs under study, regardless of the fact that the dose of cycloheximide was maximal. It is suggested that the reduction of cathepsin activities during protein biosynthesis inhibition is a regulatory mechanism by which the protein resources in the cell are preserved.