Figure 4.

The β₂AR calcium response was not mediated by AC or cAMP. a, Gα_i activation did not inhibit ISO signals. b, Gα_i activation induced changes in membrane potential. c, treatment with PTX abolished μOR-induced membrane potential changes. d–g, treatment with AC inhibitors SQ 22,536 and ddAd did not suppress signaling with ISO, even at 1 mm, although AC inhibitor treatment significantly suppressed cAMP formation (* = p = 0.0298 and ** = p = 0.0059) (f). h and i, IBMX treatment did not potentiate signaling with ISO. Ca²⁺ traces represent three or more independent experiments, and error bars indicate internal replicate S.E. Dose responses and bar graphs are the averages of three or more independent experiments, and error bars indicate S.E. AU, absorbance units.