[Effect of Ca2+-ionophore and concanavalin A on potassium permeability and membrane potential of thymocytes].

The existence of Ca2+-dependent K+ channels in rat thymocytes, their activation by Ca2+-ionophore A23187 and concanavalin A, and inhibition by EGTA and quinine have been demonstrated using K+-electrode and fluorescent potential probe diS-C3-(5). The results indicate that Ca2+-dependent K+ channels take part in the increase of potassium permeability, one of the early events in mitogenic stimulation of lymphocytes.