Greger R, Wangemann P
Lehrstuhl II Physiologie, Universität Freiburg i. Br., BRD.
Ren Physiol. 1987;10(3-4):174-83. doi: 10.1159/000173128.
Loop diuretics such as furosemide, piretanide, and bumetanide bind reversibly to the Na+2Cl-K+ carrier. This transporter is responsible for the uptake of Cl- into the thick ascending limb segment. As a consequence, these compounds reduce or abolish NaCl reabsorption in this nephron segment and lead to a decreased interstitial hypertonicity and thus to a reduced water absorption. Apart from these profound effects, loop diuretics also inhibit Ca2+ and Mg2+ reabsorption in the thick ascending limb in a manner which is still not clear. They also increase urinary K+ excretion by an increase in distal tubule NaCl and water delivery and probably also by the reduction of K+ reabsorption which goes on under in vivo conditions in the thick ascending limb segment. Finally, by the reduction of the transport work in the thick ascending limb, these compounds reduce dramatically the substrate and oxygen dependence of this nephron segment.
呋塞米、吡咯他尼和布美他尼等袢利尿剂与Na⁺-2Cl⁻-K⁺载体可逆性结合。该转运体负责将Cl⁻摄取到髓袢升支粗段。因此，这些化合物减少或消除了该肾单位段对NaCl的重吸收，导致间质高渗性降低，从而减少水的吸收。除了这些显著作用外，袢利尿剂还以尚不清楚的方式抑制髓袢升支粗段对Ca²⁺和Mg²⁺的重吸收。它们还通过增加远曲小管NaCl和水的输送，可能还通过减少髓袢升支粗段在体内条件下持续进行的K⁺重吸收，来增加尿K⁺排泄。最后，通过减少髓袢升支粗段的转运功，这些化合物显著降低了该肾单位段对底物和氧气的依赖性。
