Growth of cultured cells in low potassium medium has been shown to result in an increase in the number of Na,K-ATPase sites. This phenomenon and its physiological and pharmacological consequences were examined in spontaneously beating monolayers of cultured chick heart cells. Growth of cells in 1 mM extracellular potassium, 2 ^M ouabain, or 1 /*M veratridine for 48 hours caused 60%, 40%, or 20%...
