Pharmacological properties of GPCR agonists in SW480 cells

Agonist-stimulated DMR concentration–response curves were constructed for responses measured at endogenous receptors expressed in SW480 cells. Log molar agonist potency (as stated prior to pEC50) were calculated using the time at which peak DMR response was observed. Intrinsic activities (IA) were calculated by setting norepinephrine maximal DMR responses equal to 1 and then normalizing other observed agonist maximal DMR values to this value. All data were analyzed with GraphPad Prism using nonlinear regression curve analysis and are expressed as mean ± S.E.M. of three to four independent experiments performed with four replicates.

AgonistpEC50EC50 (μM)Max (pm)IA
Norepinephrine−5.96 ± 0.041.08354.74 ± 4.721
Isoproterenol−4.27 ± 0.1354.4151.35 ± 7.660.43
Clonidine−6.52 ± 0.120.3144.47 ± 13.20.41
Phenylephrine−5.40 ± 0.0313.9238.21 ± 4.520.67
  • IA, intrinsic activity; Max, maximum response observed in pm; ND, not determined.