人们在吸入含有二氧化硫(SO2)的空气会出现鼻阻塞反应。本研究使用麻醉猪测量SO2对鼻腔血管和气道阻力的影响以及其控制机制。将相同通气量的空气从呼出方向通入两侧鼻腔或直接经支气管入肺，测量鼻腔及支气管的气流压力并计算鼻腔及支气管气流阻力的改变。同时记录体动脉的压力和鼻腔动脉的血流量以计算血管阻力的变化。空气中含有2 ppm SO2时，血压及鼻血管阻力下降但鼻气道及支气管阻力上升。空气中SO2含量上升至8 ppm时，血压、鼻血管阻力和支气管气流阻力均上升，但鼻气道阻力下降。直接鼻腔刺激和经支气管入肺引起的反应相同。单侧鼻腔刺激引出双侧反应。钌红抑制鼻腔刺激反应。两侧迷走交感神经切除抑制肺刺激反应。因此2 ppm SO2引起经受体反射鼻血管扩张令鼻阻塞，而较高浓度SO2引发经受体反射鼻血管收缩令鼻阻塞减轻。短时间暴露(STEL)于2 ppm SO2所引起鼻阻塞及支气管收缩可限制SO2进入肺部，而较高浓度SO2引发鼻阻塞减轻可令总气道阻力下降以对抗支气管收缩产生的肺通气减少。
关键词： 二氧化硫; 鼻气道阻力; 鼻血管阻力; 鼻动脉血流; 猪鼻黏膜; 体循环动脉压
Acute effects of inhaled sulphur dioxide on pig nasal vascular and airway resistances
Mary Agnes KY Lung*
Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
People complain about nasal stuffiness after SO2 exposure. This study was to investigate the acute effects of SO2 on nasal vascular and airway resistances in anaesthetized pigs for elucidating the underlying vascular and control mechanisms. Controlled ventilation was passed to the lungs or retrogradely through each nasal cavity. Nasal airway and lower airway pressures were measured to reflect airflow resistance changes. Systemic arterial pressure and nasal arterial flow were measured to calculate nasal vascular resistance. Nasal and pulmonary SO2 challenges were given. At 2 ppm, SO2 decreased systemic blood pressure and nasal vascular resistance but increased nasal airway and lower airway resistances. With increasing level to 8 ppm, SO2 increased systemic arterial pressure, nasal vascular and lower airway resistances but decreased nasal airway resistance. Nasal and pulmonary challenges induced similar responses. Ipsilateral nasal challenge elicited bilateral responses. Ruthenium red abolished the responses to nasal challenges. Bilateral vagosympathectomy eliminated the responses to lung challenges. Hence, SO2 at 2 ppm causes nasal congestion through sensory reflex vasodilatation but at higher levels nasal decongestion through sensory reflex vasoconstriction. Nasal congestion coupled with bronchoconstriction at levels of SO2 below short-term exposure limit (STEL) (≤ 2 ppm) would limit SO2 entering the lungs. Nasal decongestion at levels of SO2 beyond STEL (> 2 ppm) can effectively decrease total airway resistance as concurrent strong bronchoconstriction may impair ventilation.
Key words: sulphur dioxide; nasal airway resistance; nasal vascular resistance; nasal blood flow; pig nasal mucosa; systemic arterial blood pressure
通讯作者：龙建音 E-mail: email@example.com
龙建音. 吸入二氧化硫对鼻腔内血管阻力及气道阻力的急性反应[J]. 生理学报 2014; 66 (1): 79-84.
Mary Agnes KY Lung. Acute effects of inhaled sulphur dioxide on pig nasal vascular and airway resistances. Acta Physiol Sin 2014; 66 (1): 79-84 (in Chinese with English abstract).