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

点击翻译按钮获取中文摘要

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.