Bradykinin receptors in signal transduction pathways in peritoneal guinea pigs macrophages

The presence of a bradykinin receptor on guinea pig peritoneal macrophages was evidenced by binding studies and by the effect of bradykinin on activation of the phospholipase C and the increase in intracellular calcium concentration ([Ca2+]i). Binding studies demonstrated a specific, saturable binding for [3H]bradykinin inhibited by the bradykinin B2 (HOe 140) but not bradykinin B1 (des-Arg9[Leu8]bradykinin) receptor antagonist. Scatchard analysis revealed a single class B2 bradykinin binding site with a binding affinity (kd) of 0.8 nM and a receptor concentration (Bmax) of 35 fmol/5 x 10(6) cells, representing approximately 4000 bradykinin receptors per cells. Kinetic studies confirmed the presence of this single binding site by the determination of similar binding affinity. Activation of peritoneal macrophages by bradykinin resulted in a time- and dose-dependent release of inositol phosphates determined by anion exchange chromatography and intracellular calcium analyzed using fura-2/AM. The increase in [Ca2+]i induced by bradykinin was blocked by the specific bradykinin B2 receptor antagonist HOE 140 but not the bradykinin B1 receptor antagonist des-Arg9[leu8]-BK. These studies provide novel information regarding the nature of kinin receptors on guinea pig peritoneal macrophages and their signal transduction pathways.