K-current mediation of prolactin-induced proliferation of malignant (Nb2) lymphocytes.

The effects of different concentrations of various K-current blockers on prolactin-induced proliferation and membrane K-currents in malignant lymphocytes (Nb2 cells) were investigated. Membrane currents were measured with the whole cell patch-clamp technique, and lymphocyte density was quantified by both spectrophotometric and conventional methods. K-current blockers tested (quinidine, 4-aminopyridine, barium, and tetraethylammonium) exhibited similar rank order potency for K-current block and inhibition of prolactin-induced proliferation of malignant lymphocytes. Because Nb2 cells proliferate independently of a transmembrane Ca-influx, these results suggest that K-currents per se rather than K-current modulation of Ca-influx is an essential event for lymphocyte proliferation.