Figure 5: PTH(1–34) activates PTH1R to produce cAMP in the presence and absence of 15 mM Ca²⁺.

HEK293S cells expressing PTH1R were stimulated with indicated concentrations of PTH(1–34) with 0 mM Ca²⁺ (red) and 15 mM Ca²⁺ (blue) for 30 minutes before harvesting to measure the concentration of cAMP. The addition of 15 mM Ca²⁺ does not change the potency of PTH(1–34) but does decrease the efficacy of PTH(1–34). Titration curves show the average of 3 experiments.