Airway reactivity in the periphery of the lung in mongrel dogs. Male and female differences.

The present study was designed to compare acute responses of the lung periphery to locally administered histamine in male and female dogs. A fiberoptic bronchoscope was wedged in peripheral airways of anesthetized dogs. Increasing doses of histamine were directed through the bronchoscope. Measurements of collateral resistance (Rcoll) were used to monitor responses to histamine and lung inflation. Baseline measurements of Rcoll were similar for both sexes. The males responded to histamine with greater increases in Rcoll than the females did. After doses of histamine (1.5 x 10(-6) mg for males and 1.5 x 10(-4) mg for females), which produced similar increases in Rcoll, the effects of lung inflation and the time course of the responses were similar for the two sexes. We conclude that male dogs exhibit greater reactivity to histamine than female dogs do. If these results apply to humans, it is possible that increased reactivity in the lung periphery contributes to the development of chronic obstructive pulmonary disease in males.