FURTHER ANALYSIS OF THE UP-REGULATION OF BRADYKININ B-1 RECEPTORS IN ISOLATED RABBIT AORTA BY USING METABOLIC-INHIBITORS

Kinins exert a contractile effect that develops as a function of the in vitro incubation time with isolated rabbit aorta. This response is mediated via receptors of the bradykinin B-1 type and interleukin-1 amplifies this upregulation process. Tissues continuously treated with the protein synthesis inhibitor cycloheximide (71 mu M) or with the protein trafficking inhibitor, brefeldin A (18 mu M), failed to develop a contractile response to the bradykinin B, receptor agonist, des-Arg(9)-bradykinin (1.7 mu M) (72-100% inhibition of kinin response recorded at 3 or 6 h), whether or not they were exposed to interleukin-1 beta (290 pM). The protein glycosylation inhibitor tunicamycin exerted a selective and significant, but partial (50-76%), inhibition of des-Arg(9)-bradykinin-induced responses. The biochemical effect of the metabolic inhibitors on the tissue has been validated in assays involving incorporation of [H-3]leucine and of [H-3]mannose into protein or glycoprotein fractions, respectively. The modulatory effects of metabolic inhibitors on the responses to kinins of the isolated rabbit aorta support the idea that a de novo formation of membrane bradykinin B, receptors is the molecular basis of both the spontaneous and the interleukin-1-stimulated upregulation phenomenon.