Wagner E M, Mitzner W A
Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland 21224, USA.
J Appl Physiol (1985). 1995 Feb;78(2):403-9. doi: 10.1152/jappl.1995.78.2.403.
Recent studies suggest a significant contribution of the pulmonary circulation to the perfusion of large airways. In this study we used anesthetized ventilated sheep (n = 19) to determine the functional contribution of the pulmonary circulation to airway smooth muscle. We performed sequential intravenous challenge with methacholine chloride (MCh; 0.25-2.5 mg/ml) to determine airway resistance (Raw) changes in the intact animal, after bronchial artery cannulation that essentially removed bronchial arterial delivery of MCh, and in an isolated lung preparation. After blocking the vagal reflex component of this response, we found that intravenous MCh in the intact preparation resulted in an average 2.2 +/- 0.5 cmH2O.l-1.s increase (181%) in Raw. After prevention of bronchial arterial delivery of MCh, Raw increased by 0.8 +/- 0.3 cmH2O.l-1.s (64%; P < 0.01 compared with intact preparation). In the isolated lung preparation, Raw increased by 0.6 +/- 0.2 cmH2O.l-1.s (63%; P < 0.01 compared with intact preparation). These results demonstrate that in sheep, the bronchial artery provides the major route for delivery of intravenously administered agonists to airway smooth muscle. Considering the large dilutional effect of an intravenously administered agonist by the time it reaches the bronchial artery, we conclude that the pulmonary component of agonist delivery to large airways is < 10% and unlikely to play a major physiological role.
近期研究表明，肺循环对大气道灌注有显著贡献。在本研究中，我们使用麻醉通气的绵羊（n = 19）来确定肺循环对气道平滑肌的功能贡献。我们依次静脉注射氯化乙酰甲胆碱（MCh；0.25 - 2.5 mg/ml），以测定完整动物、在基本消除支气管动脉对MCh输送的支气管动脉插管后以及在离体肺标本中的气道阻力（Raw）变化。在阻断该反应的迷走神经反射成分后，我们发现完整标本中静脉注射MCh导致Raw平均增加2.2±0.5 cmH₂O·l⁻¹·s（181%）。在防止支气管动脉输送MCh后，Raw增加了0.8±0.3 cmH₂O·l⁻¹·s（64%；与完整标本相比，P < 0.01）。在离体肺标本中，Raw增加了0.6±0.2 cmH₂O·l⁻¹·s（63%；与完整标本相比，P < 0.01）。这些结果表明，在绵羊中，支气管动脉是静脉注射激动剂输送至气道平滑肌的主要途径。考虑到静脉注射激动剂在到达支气管动脉时的巨大稀释效应，我们得出结论，激动剂输送至大气道的肺成分<10%，不太可能发挥主要生理作用。
