Knox A J, Ajao P
Respiratory Medicine Unit, City Hospital, Nottingham.
Thorax. 1990 Nov;45(11):856-9. doi: 10.1136/thx.45.11.856.
Frusemide, an inhibitor of sodium-potassium-chloride (Na-K-Cl) cotransport, has been shown to inhibit the airway response to several constrictor stimuli in asthmatic subjects. The protection seen with frusemide in these studies could be due to an effect on epithelium, inflammatory cells, neural pathways, or airway smooth muscle. To determine whether frusemide inhibits airway smooth muscle contraction, experiments were performed in bovine and human airways in vitro. Fresh bovine tissue was obtained from the abattoir and human tissue from thoracotomy. The effect of 10(-5)M frusemide on histamine, potassium chloride, and hyperosmolar saline induced contractions was studied in bovine tracheal strips without epithelium. Frusemide, at a concentration that specifically inhibits Na-K-Cl cotransport, did not inhibit contraction caused by any of these agents. Frusemide was also without effect on hypertonic saline induced contractions of bovine and human bronchial rings with epithelium intact. These results suggest that modification of Na-K-Cl cotransport does not alter airway smooth muscle contractility and that the protective effect of frusemide on induced bronchoconstriction in vivo is unlikely to be due to a direct effect on airway smooth muscle.
速尿是一种钠-钾-氯（Na-K-Cl）共转运抑制剂，已被证明可抑制哮喘患者气道对多种收缩刺激的反应。在这些研究中观察到的速尿的保护作用可能是由于其对上皮细胞、炎症细胞、神经通路或气道平滑肌的影响。为了确定速尿是否抑制气道平滑肌收缩，我们在体外对牛和人的气道进行了实验。新鲜的牛组织取自屠宰场，人组织取自开胸手术。在无上皮的牛气管条中研究了10（-5）M速尿对组胺、氯化钾和高渗盐水诱导的收缩的影响。速尿在特异性抑制Na-K-Cl共转运的浓度下，并不抑制这些药物引起的收缩。速尿对上皮完整的牛和人支气管环的高渗盐水诱导的收缩也没有影响。这些结果表明，Na-K-Cl共转运的改变不会改变气道平滑肌的收缩性，并且速尿对体内诱导的支气管收缩的保护作用不太可能是由于对气道平滑肌的直接作用。
