Abstract

The effects of several adrenergically reactive drugs and of triiodothyronine on the activities of five enzymes of Tetrahymena have been studied. The isocitrate dehydrogenase amid malate dehydrogenase activities were not altered by exposure to any of the drugs tested. Of three peroxisomal enzymes studied, D-amino acid oxidase activity was not affected, catalase activity was decreased by high concentrations of reserpine but either not changed or slightly increased by the other adrenergic drugs, and isocitrate lyase activity was strongly decreased by those drugs which depleted cell glycogen and slightly increased by aminophylline, which increased cell glycogen content. Thus one effect of the adrenergically reactive drugs in Tetrahymena is to alter the activity of the glyoxylate bypass pathway.