The effect of ephedrine on beta3-adrenoceptos (beta3-AR) was studied in the isolated adipose tissue of Wistar rat. Incubation with D-ephedrine (0.1-10 microM) induced a concentration-dependent decrease of uptake of [14C]-deoxy-D-glucose into white adipose tissues (WAT). The inhibitory effect of D-ephedrine was potentiated by BRL 37344, the agonist of beta3-AR and concentration-dependently inhibited by SR 59230A, the selective antagonist of beta3-AR. The action of D-ephedrine on beta3-AR was further blocked by the antibodies for beta3-AR, but not the immunoglobulin. in a concentration-dependent manner. Moreover, D-ephedrine increased glycerol release from the isolated brown adipose tissues (BAT) and this action was also abolished by SR 59230A at concentration sufficient to block beta3-AR. Thus, these results suggest that D-ephedrine has the ability to activate beta3-AR both in WAT and BAT of Wistar rats in vitro.