[3H]CGP-12177 binding to beta-adrenoceptors of intact bovine mononuclear leukocytes

Saturation and inhibition binding studies, using [3H]CGP-12177 as radioligand, reveal the presence of a single class of beta-adrenoceptors on intact bovine mononuclear leukocytes. Receptor binding is inhibited by beta-adrenergic agonists with a rank order of potency (-)-isoproterenol > (-)-epinephrine > (-)-norepinephrine, indicating that the receptors are of the beta 2-subtype. By Scatchard analysis, the mean receptor density was 707 +/- 168 receptors/cell and the dissociation constant was 0.89 +/- 0.47 nM. Specific binding was very high and amounted to 80-90%. It is concluded that [3H]CGP-12177 is a promising compound for the reliable determination of the binding characteristics of bovine mononuclear leukocytes.