心脈管感受性に及ぼす糖質コルチコイドの効果
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概要
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This study was attempted to analyze the effects of glucocorticoid on cardiovascular reactivity. In a patient with Cushing syndrome, much larger elevation of blood pressure was induced by norepinephrine administration, as compared to that in normal subject. Pretreatment with dexamethasone, significantly potentiated the blood pressure response to norepinephrine in rabbits. To elucidate the mechanism of the glucocorticoid action on the circulatory system, cardiovascular responses to norepinephrine and tissue contents of cyclic nucleotides were measured in Langendorff's isolated perfused hearts, and hind-quarter perfused preparations from rabbits pretreated with dexamethasone (3 mg/kg/day i.m. for 5 days) and papaverine(2 mg/kg i.v. 1 hour before the experiment) 1) Dose-response curves of active tension in Langendorff's hearts and that of peripheral vascular resistanse in hind-quarter preparations to norepinephrine were markedly shifted to the left by dexamethasone pretreatment. 2) By papaverine pretreatment, the curve of vascular resistance to norepinephrine was dose-dependently shifted to the right, although the response curve of active tension was shifted to the left. 3) Cyclic AMP levels were elevated in the heart with dexamethasone pretreatment. On the contrary, they were reduced in the aorta and femoral artery. Cyclic GMP levels were reduced in the heart and no significant changes in those levels were observed in the aorta and femoral artery. 4) Cyclic AMP levels were elevated in the heart and aorta by papaverine pretreatment, while there were no changes in cyclic GMP levels. It was suggested that cyclic nucleotides might be closely related to the regulation mechanism of myocardial dQntractility and vascular reactivity, and the increase in blood pressure response to norepinephrine induced by dexamethasone might be mediated by alteration of cyclic nucleotides.
- 神戸大学の論文