Bravo E L
Chest. 1983 Feb;83(2 Suppl):369-71. doi: 10.1378/chest.83.2_supplement.369.
Fifteen patients with essential hypertension and ten with pheochromocytoma were studied to assess the effect of clonidine, a centrally acting antihypertensive agent, on the functional and biochemical indices of sympathetic function. Single oral doses of clonidine (0.3 mg) decreased supine plasma norepinephrine significantly in essential hypertension, but not in pheochromocytoma despite producing similar reductions in blood pressure and heart rate. Plasma renin activity was unchanged in both groups. In untreated essential hypertension, head-up tilt increased diastolic blood pressure, heart rate, and plasma norepinephrine. Three hours after a single oral dose of clonidine, head-up tilt resulted in significant blood pressure reductions, although heart rate and plasma norepinephrine increased dramatically. Clonidine might reduce blood pressure by inhibiting sympathetic outflow, and any effect on plasma renin activity appears unimportant in its antihypertensive action. In pheochromocytoma clonidine decreases blood pressure without altering plasma norepinephrine, which is consistent with the concept that the norepinephrine released from axon terminals of sympathetic postganglionic neurons is biologically more significant than circulating catecholamines.
对15例原发性高血压患者和10例嗜铬细胞瘤患者进行了研究，以评估中枢性抗高血压药物可乐定对交感神经功能的功能和生化指标的影响。单次口服可乐定（0.3毫克）可使原发性高血压患者的仰卧位血浆去甲肾上腺素显著降低，但在嗜铬细胞瘤患者中则无此作用，尽管两组患者的血压和心率下降幅度相似。两组患者的血浆肾素活性均未改变。在未经治疗的原发性高血压患者中，头高位倾斜可使舒张压、心率和血浆去甲肾上腺素升高。单次口服可乐定3小时后，头高位倾斜导致血压显著降低，尽管心率和血浆去甲肾上腺素急剧升高。可乐定可能通过抑制交感神经传出冲动来降低血压，其对血浆肾素活性的任何影响在其降压作用中似乎并不重要。在嗜铬细胞瘤患者中，可乐定可降低血压而不改变血浆去甲肾上腺素，这与交感神经节后神经元轴突终末释放的去甲肾上腺素在生物学上比循环中的儿茶酚胺更重要的概念一致。
