Cardiopulmonary Reflex Responses during Nitric Oxide inhalation

呼吸道吸入机械刺激可引起多种心肺反应，包括血压、心率的变化以及支气管收缩等，由于人体呼吸道内存在刺激性受体、牵张性受体和J受体等多种受体，吸入一氧化氮等气体，最近临床上引入肺动脉高压或急性呼吸窘迫综合征患者吸入尼古丁，以及尼古丁烟雾，这是一个非常普遍的问题，可引起心血管变化。然而，没有关于这些问题的研究。本研究旨在探讨吸入气体和气道麻醉对反射反应的影响，结果表明：1）在麻醉犬中，5ppm和50ppm的一氧化氮（NO）对动脉压力感受性无明显影响，但显著抑制肺动脉对低氧血症的反应。2）吸烟（尼古丁0.1mg和1mg+焦油13mg）引起的软脑膜微动脉和微静脉收缩。利多卡因喷雾剂的麻醉作用可能是通过烟碱性受体和吸烟引起的交感神经兴奋而产生的。3）利多卡因喷雾剂的麻醉作用减弱了呼吸道刺激引起的动脉血压和心率的变化，而呼吸道刺激常引起心肺反射反应。在毒性剂量下，可引起大鼠动脉压力感受性反射抑制。轻度呼吸性酸中毒时抑制作用不增强，但呼吸性酸中毒时减弱。

Inhaled of mechanical stimulation to the respiratory tracts could elicit several cardiopulmonary responses, includidng changes in blood pressure and heart rate as well as bronchoconstriction and so on. Since there are many receptors such as irritant receptors, stretch receptors and J-receptors in the respiratory tracts of humans, inhaled gases such as nitric oxide, inhalation of which recently inroduced in clinically for patients with pulmonary hypertension or acute respiratory distress syndrome, and nicotine smoke, which is very a popular problem, could elicit cariovascular changes. However there has been no study available as to these points. In the present studies, we aimed to examine how inhalation of gas as well as airway anesthesia affect the reflex responses and had the following results.1)In anesthetized dogs, nitric oxide (NO), 5ppm and 50ppm, did not cause any significant influence on arterial barorefex sensitivity, but significantly suppressed pulmonary arterial responses to hypoxemia.2)Cigarette smoking (nicotine of 0.1mg and 1mg with tar of 13mg) caused to constrict pial arterioles and venules observed using the cranial window in anesthetized rats. The effets seem to be in a concentration-dependent fashione, perhaps to be via nicotinic receptors, at least partly, and sympathetic activation by cigarette smoking.3)Airwayanesthesia using lidocaine's spray attenuated the changes in arterial blood pressure and heart rate associated with airway stimulation which usually causes cardiopulmonary reflex responses in humans.Intravenous administration of bupivacaine and ropivacaine, a new local anesthetic, caused arterial baroreflex responses to suppress in their toxic dose in rats. The supression was not augumented in the presence of mild respiratory acidosis, but atttenuated in the presence of respiratory alkalosis.