Histamine N-methyltransferase Modulates Human Bronchial Smooth Muscle Contraction

[摘要] To elucidate the modulatory role of histamine-degrading enzymes inairway constrictor responses, human bronchial strips were studiedunder isometric conditionsin vitro. Pretreatment of tissues withthe histamine N-methyltransferase (HMT) inhibitor SKF 91488specifically potentiated the contractile responses to histamine,causing a leftward displacement of the concentration response curves,whereas the diamine oxidase inhibitor aminoguanidine had no effect.This potentiation was attenuated by mechanical removal of theepithelium. The HMT activity was detected in the human bronchi,which was less in the epithelium-denuded tissues than theepithelium-intact tissues. These results suggest that HMT localizedto the airway epithelium may play a protective role againsthistamine-mediated bronchoconstriction in humans.

[学科分类] 生理学与病理学