RESUMO
BACKGROUND: Changes in bronchial osmolarity is a well-known factor for bronchoconstricion. Recenty, nonisotonic aerosols have begun to be used for the assessment of bronchial hyperreactivity. Hypertonic KCl can cause bronchoconstriction even in non-symptomatic asthmatic patients. OBJECTIVE: To evaluate the protective role of heparin on hypertonic KCl-induced bronchospasm in asthma. METHODS: Thirty-eight asthmatic patients were included in this double-blind, placebo-controlled study. On day 1 of the study, after performing the respiratory function test (RFT), patients had inhaled KCl 10% and RFTs were done after 20 minutes. On day 2 of the study, after the basal RFT, 18 patents inhaled NaCl 0.9% 0.2 mLkg solution. After the completion of this procedure, patients waited for 20 minutes and inhaled KCl 10% 10 mL, and RFTs were repeated 20 minutes later. The second group consisted of 20patients who inhaled heparn 1,000 units/kg after the RFTs were performed. Twenty minutes later, they inhaled KCl 10% and waited for 20 minutes. Finally, RFTs were done and compared with those from the other group. RESULTS: In the control group, forced expiratory volume in one second (FEV1) decreased 17.4% on day 1 and 16.4% on day 2. In the heparin-treated group, FEV1 decreased 18.6% on day 1, but almost no change occurred after this group was treated with heparin before inhalation of hypertonic KCl on day 2. CONCLUSIONS: Heparin was found to be highly protective against hypertonic KCl induced bronchospasm in bronchial asthma.