en Respiratory Physiology/Pharmacology Respiratory Physiology/Pharmacology Experimental research article Experimental research article <div style="text-align: justify;"><strong><span class="fontstyle0">Introduction: </span></strong><span class="fontstyle2">The nasal airway a common route for normal breathing. Difficulty in nasal breathing due to nasal blockage is associated with abnormal respiratory pattern during sleep. The aim of this study was to investigate whether alteration in nasal airflow can change respiration pattern variability. </span><span class="fontstyle0"><strong>Methods:</strong> </span><span class="fontstyle2">Healthy male Wister rats were randomly divided into 4 groups including: control, saline, nasal obstruction and nasal cavity lidocaine anesthesia. The animals underwent bilateral nasal obstruction using cauterization and locally nasal cavity anesthesia using 10% lidocaine. Respiration of conscious animals recorded using whole-body plethysmography. </span><strong><span class="fontstyle0">Results: </span></strong><span class="fontstyle2">Respiratory signal analysis revealed a dramatic increase in variability of respiratory rhythm that quantified with increase in the standard deviation of inter-breath interval, inspiration time and mean of IBI, expiration and expiration to inspiration time ratio in both nasal obstruction and nasal anesthetized animals. Additionally, Power spectral density analysis showed higher variability in respiratory frequency, which characterized with broader dominant frequency and periodic respiratory pattern in nasal obstruction animals. </span><span class="fontstyle0"><strong>Conclusion:</strong> </span><span class="fontstyle2">These results proposed that, nasal airflow influences respiratory pattern variability. Nasal cavity flow receptors may contribute for these observations.</span></div> Nasal obstruction, Respiratory pattern, Nasal airflow, Apnea. 70 78 http://ppj.phypha.ir/browse.php?a_code=A-10-1265-3&slc_lang=en&sid=1 Saeed Pazhoohan Saeedpazhoohan@yahoo.com 3200319475328460030701 3200319475328460030701 Yes Department of Physiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran Fatemeh Abbasi Feijani 3200319475328460030702 3200319475328460030702 No Department of Physiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran Farnaz Mehrabbeigi 3200319475328460030703 3200319475328460030703 No Department of Physiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran Mohammad Reza Palizvan 3200319475328460030704 3200319475328460030704 No Department of Physiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran Saeed Hajihashemi 3200319475328460030705 3200319475328460030705 No Department of Physiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran