Katz F H, Hoehn M M
Clin Pharmacol Ther. 1977 Apr;21(4):388-91. doi: 10.1002/cpt1977214388.
Plasma renin activity and plasma aldosterone, supine and erect, and urinary aldosterone levels were measured in 18 patients on normal sodium diets and 11 patients on low sodium diets, all of whom also were on long-term levodopa therapy. Of the 230 hormone measurements, 185 were normal, 11 were high, and 34 were low. Most of the low levels were in 3 patients who had recently received fludrocortisone for orthostatic hypotension, and the renin-aldosterone systems might have been suppressed by it. In another phase of this study, 4 subjects were maintained on a constant diet for 6 wk, while the effect of gradually increasing dosages of levodopa on mineral balance and renin-aldosterone was determined. In 3 of the 4 patients there was a mild natriuretic effect of levodopa (previously demonstrated for acute levodopa therapy). There were no significant consistent changes in renin or aldosterone levels while levodopa was being administered. These studies indicate that levodopa does not usually suppress the elements of the renin-aldosterone system and that such a mechanism is unlikely to be the cause of orthostatic hypotension during the course of levodopa therapy. Since levodopa may induce natriuresis, in this situation unchanged lvels of renin and aldosterone may, however, represent an inappropriately low set of this hormonal system.
对18名正常钠饮食患者和11名低钠饮食患者进行了血浆肾素活性、仰卧位和直立位血浆醛固酮以及尿醛固酮水平的测定，所有患者均接受长期左旋多巴治疗。在230次激素测量中，185次正常，11次升高，34次降低。大多数降低情况出现在3名近期因体位性低血压接受氟氢可的松治疗的患者中，肾素 - 醛固酮系统可能被其抑制。在该研究的另一个阶段，4名受试者维持恒定饮食6周，同时测定逐渐增加左旋多巴剂量对矿物质平衡和肾素 - 醛固酮的影响。4名患者中有3名出现了左旋多巴的轻度利钠作用（先前已证明急性左旋多巴治疗时有此作用）。在给予左旋多巴期间，肾素或醛固酮水平没有显著的一致变化。这些研究表明，左旋多巴通常不会抑制肾素 - 醛固酮系统的组成部分，这种机制不太可能是左旋多巴治疗过程中体位性低血压的原因。然而，由于左旋多巴可能诱发利钠作用，在这种情况下，肾素和醛固酮水平不变可能代表该激素系统设定得过低。
