Wexels J C, Myhre E S, Mjøs O D
Can J Physiol Pharmacol. 1986 Jan;64(1):44-9. doi: 10.1139/y86-006.
We have previously demonstrated a 40% increase in myocardial blood flow (MBF) during hypercapnia but no significant decrease of MBF during hypocapnia. The present study was undertaken to evaluate if epinephrine infusion, which increases both myocardial oxygen consumption (MVo2) and myocardial performance, might influence the effects of hypocapnia and hypercapnia on MBF. Induction of hypocapnia was performed by hyperventilation in closed-chest dogs anesthetized with pentobarbital. By adding carbon dioxide to the inspiratory gas, normocapnia and hypercapnia were created. Epinephrine infusion (0.8 microgram X kg-1 X min-1) increased MBF and cardiac output (CO) by 90 and 140%, respectively, while MVo2 was increased by 45%. Epinephrine had a direct coronary vasodilating effect in excess of myocardial needs evidenced by increased oxygen content of the coronary sinus blood. During epinephrine infusion, induction of hypocapnia effected no change of MBF, while myocardial oxygen extraction increased significantly. Although oxygen saturation (So2) and Po2 in the coronary sinus blood decreased, these values remained well above those with hypocapnia without epinephrine infusion, thereby excluding impaired oxygen supply to the heart. Hypercapnia induced an increase of MBF by nearly 40% despite the coronary vasodilatation already induced by epinephrine infusion.
我们之前已经证明，高碳酸血症期间心肌血流量（MBF）增加了40%，但低碳酸血症期间MBF没有显著下降。本研究旨在评估肾上腺素输注是否会影响低碳酸血症和高碳酸血症对MBF的作用，肾上腺素输注会增加心肌耗氧量（MVo2）和心肌功能。通过对戊巴比妥麻醉的闭胸犬进行过度通气来诱导低碳酸血症。通过向吸入气体中添加二氧化碳来制造正常碳酸血症和高碳酸血症。肾上腺素输注（0.8微克×千克-1×分钟-1）使MBF和心输出量（CO）分别增加了90%和140%，而MVo2增加了45%。肾上腺素对冠状动脉有直接的舒张作用，超过了心肌的需求，这可通过冠状窦血氧含量增加得到证明。在输注肾上腺素期间，诱导低碳酸血症对MBF没有影响，而心肌氧摄取显著增加。尽管冠状窦血中的氧饱和度（So2）和氧分压（Po2）降低，但这些值仍远高于未输注肾上腺素时低碳酸血症的情况，从而排除了心脏氧供应受损的情况。尽管肾上腺素输注已经引起了冠状动脉舒张，但高碳酸血症仍使MBF增加了近40%。
