Mittelstadt S W, O'Hagan K P, Bell L B, Clifford P S
Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226.
Am J Physiol. 1994 Jun;266(6 Pt 2):R1970-5. doi: 10.1152/ajpregu.1994.266.6.R1970.
The purpose of this study was to determine if intrapericardial infusion of hexamethonium, propranolol, or atropine affected extracardiac receptors in anesthetized dogs. Intrapericardial hexamethonium (> or = 25 mg) decreased renal sympathetic nerve activity (RSNA) in a dose-dependent fashion. After 250 mg, RSNA began to decrease in 65 +/- 7 s. Whereas vagal stimulation caused a muscarinic receptor-mediated increase in tracheal smooth muscle tone (as indicated by a 9.6 +/- 1.1 mmHg increase in endotracheal cuff pressure), the increase in cuff pressure (1.8 +/- 0.4 mmHg) was attenuated after intrapericardial tropine (4 mg). When the ansa and vagus were stimulated simultaneously, beta-adrenergic receptor-mediated smooth muscle relaxation opposed the muscarinic receptor-mediated constriction resulting in an increase in cuff pressure of only 3.6 +/- 0.9 mmHg. After intrapericardial propranolol (8 mg), simultaneous ansa and vagal stimulation caused a 7.0 +/- 1.6 mmHg increase in cuff pressure, demonstrating that intrapericardial propranolol blocked beta-adrenergic receptor-mediated relaxation of tracheal smooth muscle. These results show that hexamethonium, atropine, and propranolol infused intrapericardially have extracardiac effects.
本研究的目的是确定在心包内注入六甲铵、普萘洛尔或阿托品是否会影响麻醉犬的心外受体。心包内注入六甲铵（≥25mg）会以剂量依赖的方式降低肾交感神经活动（RSNA）。注入250mg后，RSNA在65±7秒开始下降。迷走神经刺激会导致毒蕈碱受体介导的气管平滑肌张力增加（气管内套管压力增加9.6±1.1mmHg），而心包内注入阿托品（4mg）后，套管压力的增加（1.8±0.4mmHg）会减弱。当同时刺激颈袢和迷走神经时，β-肾上腺素能受体介导的平滑肌松弛会对抗毒蕈碱受体介导的收缩，导致套管压力仅增加3.6±0.9mmHg。心包内注入普萘洛尔（8mg）后，同时刺激颈袢和迷走神经会使套管压力增加7.0±1.6mmHg，表明心包内注入普萘洛尔可阻断β-肾上腺素能受体介导的气管平滑肌松弛。这些结果表明，心包内注入六甲铵、阿托品和普萘洛尔具有心外效应。
