Fisher D J
Department of Pediatrics, Baylor College of Medicine, Houston, Texas.
Pediatr Res. 1989 Jun;25(6):585-90. doi: 10.1203/00006450-198906000-00007.
The purpose of this investigation was to determine the role of increased beta-adrenergic activity in regulating the increase in myocardial oxygen consumption that occurs during hypoxemia in unanesthetized newborn lambs. Through a left thoracotomy, fluid-filled catheters were placed in the ascending aorta, coronary sinus and left atrium, a pressure transducer was introduced into the left ventricle, and pacing wires were sutured onto the left atrium. The lambs were studied 3 d later by making intermittent measurements of aortic and coronary sinus blood oxygen saturations and Hb concentrations, left ventricular myocardial blood flow, cardiac output, heart rate, left atrial and aortic blood pressures, the maximal first derivative of left ventricular pressure, aortic and coronary sinus blood oxygen contents, the arteriovenous difference of oxygen across the left ventricular myocardium, myocardial oxygen consumption, and external cardiac work (aortic mean blood pressure times cardiac output). In nine lambs with an intact beta-adrenergic nervous system (group 1), the above measurements were made during a control period and during hypoxemia (FiO2 = 0.08-0.10) with spontaneous tachycardia. In another group of 12 lambs (group 2), the measurements were made during a control period, after beta-blockade (1.5 mg/kg intravenous propranolol) with pacing at the control heart rate, during hypoxemia with pacing at the control heart rate, and during hypoxemia with pacing-induced tachycardia. In the group 2 lambs, beta-blockade completely inhibited the increase in heart rate, maximal first derivative of left ventricular pressure, cardiac output and cardiac work that occurred during hypoxemia in the group 1 lambs that had an intact beta-adrenergic nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究的目的是确定在未麻醉新生羔羊低氧血症期间，β-肾上腺素能活性增加在调节心肌耗氧量增加中所起的作用。通过左胸廓切开术，将充满液体的导管分别置于升主动脉、冠状窦和左心房，将压力传感器插入左心室，并将起搏导线缝合到左心房。3天后对羔羊进行研究，间歇性测量主动脉和冠状窦血氧饱和度及血红蛋白浓度、左心室心肌血流量、心输出量、心率、左心房和主动脉血压、左心室压力的最大一阶导数、主动脉和冠状窦血氧含量、左心室心肌的动静脉氧差、心肌耗氧量以及心脏外部做功（主动脉平均血压乘以心输出量）。在9只β-肾上腺素能神经系统完整的羔羊（第1组）中，在对照期和伴有自发心动过速的低氧血症期间（吸入氧分数=0.08 - 0.10）进行上述测量。在另一组12只羔羊（第2组）中，在对照期、静脉注射普萘洛尔（1.5mg/kg）进行β受体阻滞剂处理并以对照心率起搏后、以对照心率起搏的低氧血症期间以及起搏诱发心动过速的低氧血症期间进行测量。在第2组羔羊中，β受体阻滞剂完全抑制了第1组β-肾上腺素能神经系统完整的羔羊在低氧血症期间出现的心率增加、左心室压力的最大一阶导数增加、心输出量增加以及心脏做功增加。（摘要截于250字）
