[Sensitivity of cough with capsaicin in smokers]

In this study, effect of long term smoking on sensitivity of cough reflex was investigated. Healthy, current smoker male and female was evaluated by capsaicin cough challenge test and they were compared with healthy, non-smoker persons with similar age and gender, prospectively. In current smokers, there were 50 male and 39 female, in non-smoker control group, there were 20 male and 21 female. Mean and log C5 dosage in current smoker and non-smoker groups and mean and log C5 dosage in current smoker according to gender were calculated by using Mann-Whitney U-test. Results of capsaicin cough challenge test in current and non-smoker groups were evaluated by using Pearson Chi-Square test and Fisher's Exact test. In current smokers comparison of results of capsaicin cough challenge test with smoking history (age with first smoking, duration, pocket year and smoking per day) was evaluated by using Mann-Whitney U-test. Mean C5 and mean log C5 dosage were found decreased in current smokers when they were compared to control group (p< 0.00). In current smoker group mean C5 and mean log C5 dosage were found decreased in male (p< 0.002). When the results of capsaicin cough challenge test were compared between current smoker and control groups, sensitivity of cough reflex in concentration with 0.49, 0.98, 1.95, 3.9, 7.8, 15.6 microM was significantly decreased in current smoker group. Also there was a significant correlation between concentration with 0.98, 1.95, 3.9, 7.8, 15.6, 31.2 microM, and duration of smoking and pocket year of smoking. Also there was a correlation between concentration with 15.6, 31.2, 62.5, 125 microM and smoking per day. This results were correlated with hypothesis about inhibition of C-fibers with nicotin or decrease of C-fibers' sensitivity due to induction of neuropeptide wasting.