Boonsawat W, Salome C M, Woolcock A J
Department of Medicine, University of Sydney, New South Wales, Australia.
Am Rev Respir Dis. 1992 Sep;146(3):565-9. doi: 10.1164/ajrccm/146.3.565.
Methacholine dose response curves (DRC) in asthmatic subjects are characterized by a leftward shift and increased maximal response. Allergen inhalation in atopic subjects shifts the DRC to the left, but the effect on the shape is unknown. This study was designed to investigate the effect of allergen inhalation on the maximal response plateau of the methacholine DRC in 16 atopic subjects; nine had mild asthma and seven had rhinitis. They were challenged with allergen and with control solutions in a single-blind design. Methacholine challenges (up to 199 mumol) were performed at baseline and 24 h after the control and allergen challenges. A plateau of the DRC was defined as a difference of less than 5% in FEV1 between the last two or more doses. The maximal response was obtained by averaging the values on the plateau and was reached by all except one subject. Allergen inhalation induced an early asthmatic response (EAR) in all subjects and an additional late asthmatic response (LAR) in 6 subjects. In subjects with an EAR alone the maximal response to methacholine 24 h after allergen challenge was not different from control (mean difference, 2.9% fall in FEV1; p greater than 0.05). In subjects with LAR, the mean value for the maximal response increased from 28.5% after control to 36.5% after allergen (mean difference, 8.0%; p less than 0.05). Of six subjects who developed LAR two lost the plateau on the DRC after allergen challenge. We conclude that allergen inhalation increases the maximal response to methacholine in those subjects who have a LAR.
哮喘患者的乙酰甲胆碱剂量反应曲线（DRC）的特征是向左移位且最大反应增加。特应性受试者吸入变应原会使DRC向左移位，但对其形状的影响尚不清楚。本研究旨在调查吸入变应原对16名特应性受试者乙酰甲胆碱DRC最大反应平台的影响；其中9人患有轻度哮喘，7人患有鼻炎。他们在单盲设计中接受变应原和对照溶液的激发。在基线以及对照和变应原激发后24小时进行乙酰甲胆碱激发（最高达199μmol）。DRC的平台期定义为最后两剂或更多剂之间FEV1的差异小于5%。通过对平台期的值进行平均获得最大反应，除一名受试者外所有受试者均达到最大反应。吸入变应原在所有受试者中诱发了早期哮喘反应（EAR），在6名受试者中诱发了额外的迟发哮喘反应（LAR）。仅出现EAR的受试者在变应原激发后24小时对乙酰甲胆碱的最大反应与对照无差异（平均差异，FEV1下降2.9%；p>0.05）。在出现LAR的受试者中，最大反应的平均值从对照后的28.5%增加到变应原后的36.5%（平均差异，8.0%；p<0.05）。在出现LAR的6名受试者中，有两名在变应原激发后失去了DRC的平台期。我们得出结论，吸入变应原会增加出现LAR的受试者对乙酰甲胆碱的最大反应。
