Bailie M D, Donoso V S, Porter T M
J Pharmacol Exp Ther. 1983 May;225(2):366-71.
By using standard clearance and stop flow techniques, studies were carried out in anesthetized dogs to clarify further the mechanism(s) of excretion of renin in urine. The clearance of renin was 0.61 +/- 0.19 ml/min in control experiments and increased significantly to 1.26 +/- 0.38 ml/min after furosemide. The fractional excretion of renin increased from 1.51 +/- 0.45% during control to 3.90 +/- 0.98% after furosemide. The rate of excretion of renin was increased 10-fold during furosemide diuresis associated with a 10-fold increase in plasma renin concentration. Extracellular fluid volume expansion also produced a diuresis but no increase in plasma renin or renin excretion. Hemorrhage produced a 3.5-fold increase in plasma renin concentration and a 200-fold increase in urinary excretion of renin. When renal artery perfusion pressure was reduced to one kidney, the excretion of renin in the urine from that kidney increased, whereas there was no significant change in the excretion from the contralateral kidney. Reduction in renal artery perfusion pressure was associated with a 3-fold increase in the concentration of renin in the renal vein from the experimental kidney but an insignificant 2-fold increase in the arterial plasma renin concentration. Stop-flow studies demonstrated that renin enters the urine with the glomerular filtrate. The decreased concentration of renin in samples from the proximal tubule suggests that renin is being metabolized and/or reabsorbed in this nephron segment. In the distal nephron, there appears to be a site in which renin may be added to the tubular fluid. The results of these studies suggest that renin excretion in the urine is a complicated process. Excretion of renin in the urine is related in part to plasma renin activity but probably more importantly to the rate of production of renin in the kidney.
通过使用标准清除率和停流技术，在麻醉犬身上进行了研究，以进一步阐明肾素经尿液排泄的机制。对照实验中肾素清除率为0.61±0.19毫升/分钟，速尿给药后显著增加至1.26±0.38毫升/分钟。肾素的排泄分数从对照期间的1.51±0.45%增加至速尿给药后的3.90±0.98%。速尿利尿期间肾素排泄率增加了10倍，同时血浆肾素浓度增加了10倍。细胞外液量扩张也产生利尿作用，但血浆肾素或肾素排泄无增加。出血使血浆肾素浓度增加3.5倍，肾素尿排泄增加200倍。当一侧肾动脉灌注压降低时，该侧肾脏尿液中肾素排泄增加，而对侧肾脏排泄无显著变化。肾动脉灌注压降低与实验侧肾脏肾静脉中肾素浓度增加3倍相关，但动脉血浆肾素浓度仅无显著意义地增加2倍。停流研究表明肾素随肾小球滤过液进入尿液。近端小管样本中肾素浓度降低表明肾素在此肾单位节段被代谢和/或重吸收。在远端肾单位，似乎存在一个可将肾素添加到肾小管液中的部位。这些研究结果表明肾素经尿液排泄是一个复杂的过程。肾素经尿液排泄部分与血浆肾素活性有关，但可能更重要的是与肾脏中肾素的产生速率有关。
