Effects of Propranolol and Verapamil on Circulatory and Metabolic Responses to Various Stresses.

患有高血压和缺血性心脏病的老年外科患者经常使用β-肾上腺素能阻滞剂或钙通道拮抗剂进行治疗。这些药物可以改变循环和新陈代谢对各种压力的反应。本研究的目的是阐明氟烷或芬太尼麻醉犬对高碳酸血症、低氧血症和出血性低血容量血症反应的改善程度和差异。方法：杂种犬按麻醉用药和药物治疗分为6组。高碳酸血症由二氧化碳吸入(PaCO_2=75,100 mm Hg)、N_2-O2吸入低氧(PaO_2=60，40 mm Hg)和低血容量(平均动脉压=60，40 mm Hg)诱导。芬太尼的上述变化大于氟烷，但血钾升高。心得安和维拉帕米抑制循环改变，但增强血钾升高。2)低氧对循环和代谢的刺激作用较小。(3)出血性低血容量者心输出量明显减少，儿茶酚胺释放量增加，乳酸和血钾升高。心得安和维拉帕米在较少的出血水平增加上述变化。结论：心得安和维拉帕米抑制对高二氧化碳、低氧和低血容量的刺激反应。氟烷的抑郁程度比芬太尼更明显，心得安比维拉帕米更有效。两种药物均能增强酸中毒所致的血钾升高和循环储备。

Elderly surgical patients suffering from hypertension and ischemic heart disease are frequently treated with beta-adrenergic blocking agents or calcium channel antagonists. These drugs modify the circulatory and metabolic responses to various stresses. The aims of this study are to clarify the degree and difference of modification of resposes to hypercapnia, hypoxia and hemorrhagic hypovolemia in the dogs anesthetized with halothane or fentanyl. METHODS : Mongrel dogs were divided into 6 groups according to used anesthetics and drug treatment. Hypercapnia was induced by CO2 inhalation ( PaCO2=75,100 mmHg ), hypoxia by N2-O2 inhalation ( PaO2=60,40 mmHg ) and hypovolemia by hemorrhage ( mean arterial pressure=60,40 mmHg ).MAIN RESUKTS : 1) In hypercapnia increased catecholamine release and stimulated circulatory changes and elevation of serum K were observed. These changes were greater in fentanyl than halothane but serum K elevation. Propranolol and verapamil depressed the circulatory changes but potentiated serum K elevation. 2) Hypoxia had less stimulant effects on circulation and metabolism. 3) In hemorrhagic hypovolemia marked decrease of cardiac output and increase of catecholamine release, and elevation of lactate and serum K were observed. Propranolol and verapamil increased these changes at less hemorrhage levels.CONCLUSIONS : Propranolol and verapamil depress the stimulatory responses to hypercapnia, hypoxia and hypovolemia. The degree of depression is more pronounced in halothane than fentanyl, and propranolol is more potent than verapamil. Both drugs potentiate acidosis-induced serum K elevation and deteorirate circulatory reserve.