Häberle D A, Schiffl H, Mayer G, Davis J M, Hennings G, Rembold H
Naunyn Schmiedebergs Arch Pharmacol. 1979 Apr;306(3):287-93. doi: 10.1007/BF00507116.
The excretion of the diuretic substance DADMP (I,4-diamino-6.7-dimethylpteridine) and of DMP (6.7-dimethylpterin) was studied on single nephrons of the rat kidney using microperfusion and microinjection techniques. In the proximal tubule only DADMP was reabsorbed to a significant degree. Fractional reabsorption rate was independent of the load applied and the permeability constant was found to be 2.2 . 10(-4) cm . s-1. Similar results were obtained in nephrons in which the substances, with inulin, were injected from middle proximal tubular puncture sites and recovered in the urine. DMP appeared in the urine quantitatively and simultaneously with the injected inulin. DADMP recovery, however, was only 20--30% of the injected load during the injection period and after 2 h some 70% was recovered from the urine of both kidneys. The reabsorbed fractions were independent of the loads applied, which varied between 2 . 10(-13) mol . min-1 and 10(-9) mol . min-1. A comparison of the microperfusion and the microinfusion data suggests that the reabsorption of DADMP occurs predominantly in the proximal convolution, and it appears that the differences between the renal handling of DMP and DADMP are explicable by their different lipid solubilities.
采用微量灌注和微量注射技术，在大鼠肾脏的单个肾单位上研究了利尿物质DADMP（1,4 - 二氨基 - 6,7 - 二甲基蝶啶）和DMP（6,7 - 二甲基蝶呤）的排泄情况。在近端小管中，只有DADMP被显著重吸收。重吸收率与所施加的负荷无关，且渗透常数为2.2×10⁻⁴ cm·s⁻¹。在从近端小管中部穿刺部位注射这些物质并与菊粉一起在尿液中回收的肾单位中也获得了类似结果。DMP定量出现在尿液中，且与注射的菊粉同时出现。然而，在注射期间，DADMP的回收率仅为注射量的20% - 30%，2小时后，约70%从双侧肾脏的尿液中回收。重吸收分数与所施加的负荷无关，负荷在2×10⁻¹³ mol·min⁻¹至10⁻⁹ mol·min⁻¹之间变化。微量灌注和微量注射数据的比较表明，DADMP的重吸收主要发生在近端曲部，而且似乎DMP和DADMP在肾脏处理上的差异可以用它们不同的脂溶性来解释。
