Changes in Plasma Bradykinin Concentration and Citric Acid Cough Threshold at High Altitude
Wilderness & Environmental Medicine(2009)
摘要
Objective.-Altitude-related cough is a troublesome condition Of unknown etiology. inhaled tussive agents are used to quantity Cough, and the citric acid cough threshold has been shown to fall oil ascent to altitude. Cough can occur in patients taking angiotensin-converting enzyme inhibitors Clue to stimulation of airway sensory receptors by increased levels of bradykinin. We hypothesized that increased levels of bradykinin Could be responsible for the decrease in citric acid cough threshold Oil exposure to altitude and a possible etiologic factor in altitude-related cough. Methods.-Twenty healthy volunteers underwent baseline tests Lit 700 in before a 2-week stay at 3900 m. Angiotensin-converting enzyme activity and plasma bradykinin were measured at baseline and altitude. Citric acid cough threshold and nocturnal cough frequency were measured Lit baseline and throughout the 2 weeks at attitude. Results.-Citric acid cough threshold fell from 3.7 g/dL at baseline to 2.1 g/dL on the second day at 3800 m (geometric mean difference 1.8, 95% CIs 1.0-5.0, P = .025) and remained reduced throughout the stay at altitude. Nocturnal Cough frequency was unchanged compared to baseline. Plasma bradykinin fell from 0.43 ng/mL at baseline to 0.08 ng/mL at altitude (geometric mean difference 5.7, 95% CIs 2.1-15.5, P = .002), but angiotensin-converting enzyme activity Was unchanged (mean difference 0.06, 95% CIs -2.7-2.8, P = .97). There was no correlation between plasma bradykinin and citric acid Cough threshold. Conclusions.-Increased levels of bradykinin are unlikely to be a significant factor in the increased sensitivity to citric acid seen in hypobaric hypoxia. Further Studies are required to elucidate the etiology of altitude-related cough.
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关键词
Altitude-related cough,bradykinin,pulmonary edema,citric acid cough threshold
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