Jazayeri A, Meyer W J
Department of Psychiatry and Behavioral Sciences, University of Texas Medical Branch, Galveston 77550.
Hypertension. 1988 Oct;12(4):393-8. doi: 10.1161/01.hyp.12.4.393.
Since both glucocorticoids and catecholamines are involved in the regulation of normal blood pressure, we investigated the modulation of beta-adrenergic receptors of cultured rat arterial smooth muscle cells by glucocorticoids. The synthetic glucocorticoids dexamethasone and RU 28362, at 10(-8) M concentration, increased maximum beta-adrenergic binding but had no effect on the dissociation constant (Kd). Each steroid caused an increase in maximum [3H]dihydroalprenolol binding over the concentration range of 10(-8) to 10(-6) M, but not at 10(-9) M. The glucocorticoid effect on beta-adrenergic receptors of arterial smooth muscle cells required a minimum of 20 hours of incubation in the presence of the steroid and was significantly inhibited by cycloheximide (10 micrograms/ml), indicating that the glucocorticoid effect required protein synthesis. The effect of dexamethasone on [3H]dihydroalprenolol binding was significantly inhibited by the glucocorticoid antagonist RU 38486. Basal and agonist-stimulated cyclic adenosine 3',5'-monophosphate (cAMP) levels in arterial smooth muscle cells, before and after glucocorticoid treatment, were measured as an indicator of the physiological significance of the observed glucocorticoid-induced increase in beta-adrenergic receptor binding. While causing no change in the basal cAMP level, treatment of arterial smooth muscle cells with 10(-6) M dexamethasone for 24 hours increased the 10(-6) M isoproterenol-stimulated cAMP levels.
由于糖皮质激素和儿茶酚胺都参与正常血压的调节，我们研究了糖皮质激素对培养的大鼠动脉平滑肌细胞β-肾上腺素能受体的调节作用。合成糖皮质激素地塞米松和RU 28362，在浓度为10^(-8) M时，增加了最大β-肾上腺素能结合，但对解离常数（Kd）没有影响。在10^(-8)至10^(-6) M的浓度范围内，每种类固醇都导致最大[3H]二氢阿普洛尔结合增加，但在10^(-9) M时没有增加。糖皮质激素对动脉平滑肌细胞β-肾上腺素能受体的作用在类固醇存在下至少需要20小时的孵育，并且被环己酰亚胺（10微克/毫升）显著抑制，这表明糖皮质激素的作用需要蛋白质合成。地塞米松对[3H]二氢阿普洛尔结合的作用被糖皮质激素拮抗剂RU 38486显著抑制。测量糖皮质激素处理前后动脉平滑肌细胞中的基础和激动剂刺激的环磷酸腺苷（cAMP）水平，作为观察到的糖皮质激素诱导的β-肾上腺素能受体结合增加的生理意义的指标。虽然基础cAMP水平没有变化，但用10^(-6) M地塞米松处理动脉平滑肌细胞24小时增加了10^(-6) M异丙肾上腺素刺激的cAMP水平。
