Effects of Inhaled L-Arginine Administration in A Murine Model of Acute Asthma

Increased arginase activity in the airways decreases L-arginine and causes deficiency of bronchodilating and anti-inflammatory nitric oxide (NO) in asthma. As, it is suggested that L-arginine may have therapeutic potential in asthma treatment, we aimed to investigate the effects of inhaled L-arginine on oxygen saturation (SaO2) and airway histology in a murine model of acute asthma.Twenty eight BALB/c mice were divided into four groups; I, II, III and IV (control). All groups except the control were sensitized and challenged with ovalbumin. After establishement of acute asthma attack by metacholine administration, the mice were treated with inhaled L-arginine (Group I), saline (Group II) and budesonide (Group III), respectively. SaO2 was measured by pulse oximeter just before and 5 min after methacholine. A third measurement of SaO2 was also obtained 15 min after drug administration in these study groups. Inflammation in the lung tissues of the sacrificed animals were scored to determine the effects of the study drugs. The number of eosinophils in bronchoalveolar lavage (BAL) was determined.The results indicated that inflammatory scores significantly improved in groups receiving study drugs when compared with placebo and L-arginine was similar in decreasing scores when compared with budesonide. SaO2 had a tendency to increase after L-arginine administration after acute asthma attack and this increase was statistically significant (p=0.043). Eosinophilia in BAL significantly reduced in group receiving L-arginine when compared with placebo (p<0.05).Thus in this study we demonstrated that L-arginine improved SaO2 and inflammatory scores in an acute model of asthma.