Nonsmoker patients between range of 18 to 75 yr with a history of persistent asthma that do not have heart disease, other underlying disease(diabetes mellitus, hypertension, malignancy, bronchiectasis and …) or respiratory diseases other than asthma and don’t use any medications except for asthma included in the trial. Data are gradually gathered in a sequential trial. In this trial asthma diagnosis basis is history of cough, sputum, intermittent and variable dyspnea, wheezing, and chest tightness for at least 6 months. Chest x ray should be free of fibrosis, lobar pneumonia, bronchiectasis, and mass. Diagnosis of asthma has been confirmed previously by subspecialists.Initially for patients who arrive trial a physician fills a questionnaire for age, gender, and other variables. One part of questionnaire belongs to estimating persistent asthma severity and based on frequency of daily and nocturnal asthma attacks patients are divided into three groups of mild, moderate and severe persistent asthma.Then after patient is tested by a spirometry and its indices are recorded.In order to simulate both groups of patients before administering nebulizers, on the basis of age asthma underlying persistent severity physician and spirometry indices decides which patient is included in case or control group.Then patient is settled in a silent room and receives a nebulized salbutamol(2.5mg) or nebulized lasix(10mg) plus salbutamol(2.5mg) diluted in 1 cc instilled water. Fifteen minutes after nebulizer finished a repeated spirometry is done and indices are recorded.For all patients spirometry machine and nebulizer equipments are the same.