Berndt T J, MacDonald A, Walikonis R, Chinnow S, Dousa T P, Tyce G M, Knox F G
Department of Physiology and Biophysics, Mayo Clinic and Foundation, Rochester, MN 55905.
J Lab Clin Med. 1993 Jul;122(1):80-4.
The urinary excretion of free dopamine, norepinephrine, and epinephrine could reflect the contribution of the neural release and filtration of these catecholamines as well as the intrarenal tubular synthesis and metabolism of dopamine. Because these catecholamines are rapidly metabolized, the excretion of the free amines represents only a fraction of the total release and synthesis by the kidney. The present study determined the effect of increasing dietary phosphate intake on the excretion of free dopamine, norepinephrine, and epinephrine and their primary stable metabolites. Seven male rats were placed in metabolic balance cages and fed 12 gm/day of normal phosphate diet (NPD) (0.7% inorganic phosphorus [Pi]) for 4 days and then fed a high phosphate diet (HPD) (1.8% Pi) for 4 days. Twenty-four-hour urine samples were collected for determination of free catecholamines, their major stable metabolites, and electrolyte excretions. The urinary excretion data for the seven rats was combined for all 4 days of each dietary regimen. Increasing phosphate intake from 0.7% to 1.8% significantly increased free dopamine excretion by 23%, from 5.6 +/- 0.2 to 6.8 +/- 0.1 micrograms/day (n = 7, p < 0.05). This increase in free dopamine excretion was associated with similar increases in urinary excretion of dopamine glucuronide, 21.6 +/- 1.3 to 27.9 +/- 1.8 micrograms/day (32%) and the dopamine metabolite DOPAC, 9.4 +/- 0.5 to 12.1 +/- 0.6 micrograms/day (30%) and total dopamine excretion from 32.9 +/- 1.7 to 41.0 +/- 1.9 micrograms/day (27%). Plasma DOPA levels were unchanged by increased dietary phosphate intake; however, plasma norepinephrine levels decreased significantly. Excretion of free or sulfated norepinephrine was not changed by increased phosphate intake. However, excretion of MHPG, a metabolite of norepinephrine and epinephrine, decreased significantly, from 33.7 +/- 2.1 to 23.9 +/- 0.8 micrograms/day, n = 7, p < 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)
游离多巴胺、去甲肾上腺素和肾上腺素的尿排泄量可反映这些儿茶酚胺的神经释放和滤过作用，以及多巴胺在肾小管内的合成和代谢情况。由于这些儿茶酚胺会迅速代谢，游离胺的排泄量仅占肾脏总释放和合成量的一小部分。本研究确定了增加饮食中磷摄入量对游离多巴胺、去甲肾上腺素和肾上腺素及其主要稳定代谢产物排泄的影响。将7只雄性大鼠置于代谢平衡笼中，先给予12克/天的正常磷饮食（NPD）（0.7%无机磷[Pi]），持续4天，然后给予高磷饮食（HPD）（1.8% Pi），持续4天。收集24小时尿液样本，用于测定游离儿茶酚胺、其主要稳定代谢产物和电解质排泄量。将7只大鼠在每种饮食方案的所有4天中的尿排泄数据合并。将磷摄入量从0.7%增加到1.8%，可使游离多巴胺排泄量显著增加23%，从5.6±0.2微克/天增至6.8±0.1微克/天（n = 7，p < 0.05）。游离多巴胺排泄量的增加与多巴胺葡糖醛酸苷尿排泄量的类似增加相关，从21.6±1.3微克/天增至27.9±1.8微克/天（32%），多巴胺代谢产物DOPAC从9.4±0.5微克/天增至12.1±0.6微克/天（30%），总多巴胺排泄量从32.9±1.7微克/天增至41.0±1.9微克/天（27%）。饮食中磷摄入量增加并未改变血浆多巴水平；然而，血浆去甲肾上腺素水平显著降低。磷摄入量增加并未改变游离或硫酸化去甲肾上腺素的排泄量。然而，去甲肾上腺素和肾上腺素的代谢产物MHPG的排泄量显著降低，从33.7±2.1微克/天降至23.9±0.8微克/天，n = 7，p < 0.05。（摘要截断于250字）
