Baile E M, McKay K, Wang L, Bai T R, Paré P D
University of British Columbia Pulmonary Research Laboratory, St. Paul's Hospital, Vancouver, British Columbia, Canada V6Z 1Y6.
J Appl Physiol (1985). 1998 Mar;84(3):809-14. doi: 10.1152/jappl.1998.84.3.809.
Endogenous nitric oxide (NO) influences acetylcholine-induced bronchovascular dilation in sheep and is a mediator of the airway smooth muscle inhibitory nonadrenergic, noncholinergic neural response in several species. This study was designed to determine the importance of NO as a neurally derived modulator of ovine airway and bronchial vascular smooth muscle. We measured the response of pulmonary resistance (RL) and bronchial blood flow (Qbr) to vagal stimulation in 14 anesthetized, ventilated, open-chest sheep during the following conditions: 1) control; 2) infusion of the alpha-agonist phenylephrine to reduce baseline Qbr by the same amount as would be produced by infusion of Nomega-nitro-L-arginine (L-NNA), a NO synthase inhibitor; 3) infusion of L-NNA (10(-2) M); and 4) after administration of atropine (1.5 mg/kg). The results showed that vagal stimulation produced an increase in RL and Qbr in periods 1, 2, and 3 (P < 0.01) that was not affected by L-NNA. After atropine was administered, there was no increase in Qbr or RL. In vitro experiments on trachealis smooth muscle contracted with carbachol showed no effect of L-NNA on neural relaxation but showed a complete blockade with propranolol (P < 0.01). In conclusion, the vagally induced airway smooth muscle contraction and bronchial vascular dilation are not influenced by NO, and the sheep's trachealis muscle, unlike that in several other species, does not have inhibitory nonadrenergic, noncholinergic innervation.
内源性一氧化氮（NO）影响绵羊体内乙酰胆碱诱导的支气管血管舒张，并且在多个物种中是气道平滑肌抑制性非肾上腺素能、非胆碱能神经反应的介质。本研究旨在确定NO作为绵羊气道和支气管血管平滑肌神经源性调节剂的重要性。我们在以下条件下测量了14只麻醉、通气、开胸绵羊的肺阻力（RL）和支气管血流量（Qbr）对迷走神经刺激的反应：1）对照；2）输注α-激动剂去氧肾上腺素，以将基线Qbr降低至与输注NO合酶抑制剂Nω-硝基-L-精氨酸（L-NNA）所产生的降低量相同；3）输注L-NNA（10⁻² M）；4）给予阿托品（1.5 mg/kg）后。结果表明，在第1、2和3阶段，迷走神经刺激使RL和Qbr增加（P < 0.01），且不受L-NNA影响。给予阿托品后，Qbr或RL没有增加。对用卡巴胆碱收缩的气管平滑肌进行的体外实验表明，L-NNA对神经舒张没有影响，但普萘洛尔可完全阻断（P < 0.01）。总之，迷走神经诱导的气道平滑肌收缩和支气管血管舒张不受NO影响，并且与其他几个物种不同，绵羊的气管平滑肌没有抑制性非肾上腺素能、非胆碱能神经支配。
