Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 13 5 2014 10 15 317 323 EN Zeynep Arikan-Ayyildiz Department of Pediatric Allergy and Immunology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Meral Karaman Department of Experimental Animal Laboratory, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Fatih Firinci Department of Pediatric Allergy and Immunology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Muge Kiray Department of Physiology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Alper Bagriyanik Department of Histology and Embryology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Osman Yilmaz Department of Experimental Animal Laboratory, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Nevin Uzuner Department of Pediatric Allergy and Immunology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. Ozkan Karaman Department of Pediatric Allergy and Immunology, Dokuz Eylul University Faculty of Medicine, Izmir, Turkey. 2015 10 16 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. SaO₂was measured by pulse oximeter just before and 5 min after methacholine. A third measurement of SaO₂was 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. SaO₂had 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 SaO₂and inflammatory scores in an acute model of asthma. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/438 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/438/399