glucocorticoideffects on glucoseutilization by normal lymphocytesare precededby the following sequenceof

Events preceding the cortisol inhibition of uridine utiliza tion by corticoid-sensitive P1798 lymphocytes have been investigated. When tumor cells were incubated with I @M cortisol for IS mm and then washed free of steroid and reincubated in the absence of hormone, the expected decrease of uridine uptake failed to appear 1.5 hr later. In Contrast, the removal of cortisol after 30 or 60 mm did not prevent subsequent development of the steroid effect. Addi tion of actinomycin D with cortisol, or IS mm after hormone treatment was started, blocked steroid action. However, when actinomycin D was added 30 or 60 mm after the initial exposure to cortisol, hormone-induced depression of uridine uptake was no longer prevented. To study the role of protein synthesis, cycloheximide was added to the tumor cell suspensions at various times after cortisol treatment