Long-term enhancement of Na,K-ATPase pump during blasttransformation of human lymphocytes is controlled first by translational, then by transcriptional mechanisms.

The transition of phytohemagglutinin-activated human lymphocytes from resting state to proliferation is accompanied by a long-term increase in ouabain-sensitive Rb(K) influx which is closely related to a cyclosporin A-sensitive step of G0/G1/S progression. At least two distinct phases of the up-regulation of cation pump has been revealed: the initial stage (5-20 h) which is cycloheximide-inhibitable and actinomycin D (alpha-amanitin)-unaffected, and the later stage (after 20 h) which is cycloheximide- and actinomycin D (alpha-amanitin)-inhibitable. Thus, the enhanced Na,K-ATPase pump during the cell progression from quiescence to proliferation is controlled both at translational and transcriptional levels.