We studied the effect of the external addition of noradrenaline (NA) on the electrical activity of white adipocytes from rat epididymal tissue. NA modified the active voltage response recorded by the current clamp technique, and decreased the macroscopic membrane potassium currents measured by a whole-cell configuration patch-clamp technique in cells obtained by culturing differentiating preadipocytes. To analyse if cAMP is implicated in the effect of this hormone on potassium conductances, the changes in electrical activity caused by an increase in the intracellular concentration of cAMP were studied using intracellular recording. The addition of forskolin, or NN-dibutyryl cAMP plus 3-isobutyl-1-methylxanthine to the bath reduced active changes in membrane voltage responses to hyperpolarizing and depolarizing pulses. A similar effect was observed when vasoactive intestinal peptide was added to the superfusion chamber. These results suggest that NA could modulate K+ conductances in white adipocytes, mediated by cAMP.