Figure 1

Calcium responses in cells co-transfected with different rat and human TAS1R subunits to stimulation with various sweeteners in the presence and absence of lactisole. (a) Intracellular calcium traces recorded in the FLIPR. Upper panel: Responses of cells cotransfected with cDNAs hTAS1R2 and hTAS1R3. Lower panel: Response of cells co-transfected with cDNAs rTas1r2 and rTas1r3. The cells were challenged with 3 mM saccharin containing 0.0, 0.01, 0.1, or 1.0 mM lactisole. Arrows denote the time of application. Signals were averaged over three independent wells of a FLIPR plate. Vertical scale, 1000 counts; horizontal scale, 1 min. (b) Cells co-transfected with hTAS1R2-hTAS1R3, (c) rTas1r2-rTas1r3, (d) hTAS1R2-rTas1r3, or (e) rTas1r2-hTAS1R3. c, response of mock-transfected control cells; lac, 1.0 mM lactisole; asp, 15 mM aspartame; cyc, 30 mM cyclamate; neo, 0.1 mM neohesperidine dihydrochalcone; sac, 10 mM saccharin; suc, 100 mM sucrose; stev, 1 mM stevioside; -, response without lactisole; +, response in the presence of 1.0 mM lactisole. All sweeteners were used at concentrations which were close to the maximal obtainable signal.