Department of Nephrology, Medical University of Lublin, Jaczewskiego 8, 20-954, Lublin, Poland.
Department of Biopharmacy, Medical University of Lublin, Chodźki 4a, 20-093, Lublin, Poland.
Pharmacol Rep. 2024 Dec;76(6):1415-1428. doi: 10.1007/s43440-024-00648-8. Epub 2024 Sep 11.
Loop diuretics became a cornerstone in the therapy of hypervolemia in patients with chronic kidney disease or heart failure. Apart from the influence on water and electrolyte balance, these drugs were shown to inhibit tissue fibrosis and renin-angiotensin-system activity. The kynurenine (KYN) pathway products are suggested to be uremic toxins. Kynurenic acid (KYNA) is synthesized by kynurenine aminotransferases (KATs) in the brain and periphery. The cardiovascular and renal effects of KYNA are well documented. However, high KYNA levels have been correlated with the rate of kidney damage and its complications. Our study aimed to assess the effect of loop diuretics, ethacrynic acid, furosemide, and torasemide on KYNA synthesis and KATs activity in rat kidneys in vitro.
Quantitative analyses of KYNA were performed using fluorimetric HPLC detection. Additionally, molecular docking studies determined the possible interactions of investigated compounds with an active site of KAT I and KAT II.
All studied drugs inhibited KYNA production in rat kidneys in vitro at 0.5-1.0 mmol/l concentrations. Only ethacrynic acid at 1.0 mmol/l concentration significantly lowered KAT I and KAT II activity in kidney homogenates, whereas other drugs were ineffective. Molecular docking results indicated the common binding site for each of the studied loop diuretics and KYNA. They suggested possible residues involved in their binding to the active site of both KAT I and KAT II model.
Our study reveals that loop diuretics may decrease KYNA synthesis in rat kidneys in vitro. The presented results warrant further research in the context of KYN pathway activity regulation by loop diuretics.
在慢性肾病或心力衰竭患者的水肿治疗中，袢利尿剂已成为基石。除了对水和电解质平衡的影响外，这些药物还被证明能抑制组织纤维化和肾素-血管紧张素系统的活性。犬尿氨酸（KYN）途径产物被认为是尿毒症毒素。犬尿氨酸氨基转移酶（KATs）在大脑和外周组织中合成犬尿氨酸（KYNA）。KYNA 的心血管和肾脏作用已得到充分证实。然而，高 KYNA 水平与肾脏损害及其并发症的发生率相关。我们的研究旨在评估在体外用袢利尿剂、依他尼酸、呋塞米和托拉塞米对大鼠肾脏 KYNA 合成和 KATs 活性的影响。
采用荧光 HPLC 检测法对 KYNA 进行定量分析。此外，分子对接研究确定了研究化合物与 KAT I 和 KAT II 活性部位的可能相互作用。
所有研究的药物在 0.5-1.0 mmol/l 浓度下均能抑制大鼠肾脏中 KYNA 的体外产生。只有依他尼酸在 1.0 mmol/l 浓度下显著降低了肾匀浆中 KAT I 和 KAT II 的活性，而其他药物则无效。分子对接结果表明，研究的每一种袢利尿剂与 KYNA 都有共同的结合位点。它们提示了可能涉及它们与 KAT I 和 KAT II 模型的活性部位结合的残基。
我们的研究表明，袢利尿剂可能会降低大鼠肾脏中 KYNA 的体外合成。这些结果表明，有必要进一步研究袢利尿剂对 KYN 途径活性的调节作用。
