Knauf H, Schollmeyer P, Steinhardt H J
Clin Nephrol. 1975;3(4):148-52.
The effect of furosemide and amiloride on the transport of sodium, potassium, hydrogen and bicarbonate ions was studied in microperfusion experiments on the main excretory duct of the submaxillary gland of the rat. Furosemide did not impair transport of Na+, K+ and H+/HCO-3. Amiloride, however, completely abolished Na+ transport. Blockade of Na+ transport was accompanied by abolition of passive K+ secretion, whereas the active components of K+ and HCO-3 secretion were not affected. In urinary excretion studies, amiloride, which is known to block sodium transport selectively, was used in order to assess whether furosemide has a distinct effect that is independent of sodium transport. Oral administration of amiloride caused a selective excretion of Na+ in a more alkaline urine with an extremely low K+ concentration. The injection of furosemide caused a copious diuresis of an isotonic urine, in which excretion of Na+ and K+ was balanced by the excretion of Cl- ions. Combined administration of amiloride and furosemide produced summation of the individual effects of both diuretics, indicating that the two drugs had different sites and modes of action. In the presence of furosemide the kidney no longer responded to antidiuretic hormone, which suggested that the urine concentrating mechanism in Henle's loop was blocked by furosemide.
在大鼠下颌下腺主排泄管的微灌注实验中，研究了呋塞米和阿米洛利对钠、钾、氢和碳酸氢根离子转运的影响。呋塞米不损害Na⁺、K⁺和H⁺/HCO₃⁻的转运。然而，阿米洛利完全消除了Na⁺的转运。Na⁺转运的阻断伴随着被动K⁺分泌的消除，而K⁺和HCO₃⁻分泌的主动成分未受影响。在尿排泄研究中，使用已知能选择性阻断钠转运的阿米洛利，以评估呋塞米是否具有独立于钠转运的独特作用。口服阿米洛利导致Na⁺在碱性更强、K⁺浓度极低的尿液中选择性排泄。注射呋塞米导致等渗尿液大量利尿，其中Na⁺和K⁺的排泄由Cl⁻离子的排泄平衡。联合给予阿米洛利和呋塞米产生了两种利尿剂各自作用的总和，表明这两种药物具有不同的作用部位和作用方式。在呋塞米存在的情况下，肾脏不再对抗利尿激素产生反应，这表明呋塞米阻断了亨利袢中的尿液浓缩机制。
