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OF NUDE STRIPS AND PEPTIDES
Bradykinin is a peptide that is a potent bronchoconstrictor and could thus be an important inflammatory mediator in asthma. A research group at BioPharmacol Enterprises have been studying the effects of a novel drug BP239 on the responses of human bronchioles to exogenously added bradykinin.
They dissected out the bronchioles and cut them spirally to obtain strips which were mounted in organ baths and the tension generated in response to different drugs was recorded. Two kinds of bronchiolar strips were used. In the normal strips the bronchiolar epithelium was left intact whereas in the denuded set, the epithelium was carefully removed and the removal checked by histology. The responses were tested in the presence and absence of the drug BP239. The results are shown below.
Figure shows the cumulative responses of bronchiolar strips to exogenously added bradykinin. The data are expressed relative to the maximal tension developed in response to a standard agonist, methacholine (a cholinergic drug). Both normal and denuded strips were tested in the presence and absence of a novel drug (BP239). The data are mean values, the error bars have been deleted for the sake of clarity. The responses of normal and denuded strips in the absence of BP239 were significantly different from each other. However in the presence of BP239 no differences were noted between normal and denuded strips.
Several possible explanations can be given. For instance, the epithelium could be producing an inhibitory substance that either limited responses to the peptide or even degraded it, it could have acted as a mere barrier to the access of bradykinin to the receptor, etc. Again the novel drug could be a general antagonist to bradykinin or to the production of some substance released by bradykinin that was responsible for the contractile effect.