Boskabady Mohammad H, Teymoory Simin
Dept. of Physiology, Ghaem Medical Centre, Mashhad University of Medical Sciences, Mashhad, Iran.
Med Sci Monit. 2003 Sep;9(9):BR336-42.
There is controversy regarding bronchial responsiveness to b2-agonist drugs in asthma. Epithelial shedding in the airways is a pathological feature of asthma. Therefore, the present study focused on the effect of epithelial denudation of guinea pig tracheal chains in response to isoprenaline and b-adrenergic receptor blockade.
MATERIAL/METHODS: In control (group 1, n=10), epithelium-denuded (group 2, n=10), and epithelium-denuded + epithelial cell (group 3 n=6) we measured the responses of tracheal chains to cumulative concentrations of isoprenaline (I) in the absence and presence of 10 nM propranolol, and the value of EC50I was calculated. The propranolol blockade (CR-1) was calculated as the ratio of post propranolol EC50I to initial EC50I.
The tracheal responses to isoprenaline (EC50I) in groups 2 and 3 was significantly higher than in the controls (p<0.05 for both cases), but was not significantly different between the groups 2 and 3. The values of CR-1 in group 2 only was significantly higher than the controls (p<0.001). The mean CR-1 in group 3 was significantly lower than in group 2 (p<0.01). There was significant negative correlation between EC50I and CR-1 in all three groups (p=0.002).
The results of this study indicate increased tracheal response to a b-adrenergic stimulating drug in both groups 1 and 2, and enhancement of b-adrenergic blockade by propranolol only in group 1. These results may indicate some of the mechanisms of asthma aggravation by b2-antagonist drugs.
关于哮喘患者支气管对β2-激动剂药物的反应性存在争议。气道上皮脱落是哮喘的一个病理特征。因此，本研究聚焦于豚鼠气管链上皮剥脱对异丙肾上腺素和β-肾上腺素能受体阻断的反应。
材料/方法：在对照组（第1组，n = 10）、上皮剥脱组（第2组，n = 10）和上皮剥脱+上皮细胞组（第3组，n = 6）中，我们测量了气管链在有无10 nM普萘洛尔存在时对累积浓度异丙肾上腺素（I）的反应，并计算了EC50I值。普萘洛尔阻断率（CR-1）计算为普萘洛尔作用后的EC50I与初始EC50I的比值。
第2组和第3组气管对异丙肾上腺素（EC50I）的反应显著高于对照组（两种情况均p<0.05），但第2组和第3组之间无显著差异。仅第2组的CR-1值显著高于对照组（p<0.001）。第3组的平均CR-1显著低于第2组（p<0.01）。三组中EC50I与CR-1之间均存在显著负相关（p = 0.002）。
本研究结果表明，第1组和第2组气管对β-肾上腺素能刺激药物的反应均增加，且仅第1组中普萘洛尔增强了β-肾上腺素能阻断。这些结果可能提示了β2-拮抗剂药物加重哮喘的一些机制。
