Histamine and pulmonary responses to cigarette smoke in periphery of the lung

An animal model for studying responses of the lung periphery to controlled levels of environmental agents has been used to assess the role of histamine in pulmonary responses to cigarette smoke. A fiber-optic bronchoscope was wedged in a peripheral airway of anesthetized dogs. Measurements of collateral resistance (Rcoll) were used to monitor responses to histamine and cigarette smoke. Responses to an aerosol containing histamine (1.5 X 10(-4) mg) and cigarette smoke (420 ml) were measured before and after the administration of an aerosol containing 1.0 mg chlorpheniramine. Prior to the administration of chlorpheniramine, the histamine challenge produced a 75 +/- 26% increase in Rcoll and cigarette smoke produced a 74 +/- 26% increase. Following the administration of chlorpheniramine, the peak responses to histamine and cigarette smoke were reduced by 82 +/- 9 and 61 +/- 8%, respectively. Administration of the same dose of chlorpheniramine prior to challenge with methacholine did not reduce the response to that agent. These results indicate that acute local responses to cigarette smoke in the periphery of the lung are mediated in part through the release of histamine.