Zhang Yue, Peti-Peterdi Janos, Müller Christa E, Carlson Noel G, Baqi Younis, Strasburg David L, Heiney Kristina M, Villanueva Karie, Kohan Donald E, Kishore Bellamkonda K
Nephrology Research and Department of Internal Medicine.
Zilkha Neurogenetic Institute and Department of Physiology and Biophysics, University of Southern California, Los Angeles, California;
J Am Soc Nephrol. 2015 Dec;26(12):2978-87. doi: 10.1681/ASN.2014010118. Epub 2015 Apr 8.
P2Y12 receptor (P2Y12-R) signaling is mediated through Gi, ultimately reducing cellular cAMP levels. Because cAMP is a central modulator of arginine vasopressin (AVP)-induced water transport in the renal collecting duct (CD), we hypothesized that if expressed in the CD, P2Y12-R may play a role in renal handling of water in health and in nephrogenic diabetes insipidus. We found P2Y12-R mRNA expression in rat kidney, and immunolocalized its protein and aquaporin-2 (AQP2) in CD principal cells. Administration of clopidogrel bisulfate, an irreversible inhibitor of P2Y12-R, significantly increased urine concentration and AQP2 protein in the kidneys of Sprague-Dawley rats. Notably, clopidogrel did not alter urine concentration in Brattleboro rats that lack AVP. Clopidogrel administration also significantly ameliorated lithium-induced polyuria, improved urine concentrating ability and AQP2 protein abundance, and reversed the lithium-induced increase in free-water excretion, without decreasing blood or kidney tissue lithium levels. Clopidogrel administration also augmented the lithium-induced increase in urinary AVP excretion and suppressed the lithium-induced increase in urinary nitrates/nitrites (nitric oxide production) and 8-isoprostane (oxidative stress). Furthermore, selective blockade of P2Y12-R by the reversible antagonist PSB-0739 in primary cultures of rat inner medullary CD cells potentiated the expression of AQP2 and AQP3 mRNA, and cAMP production induced by dDAVP (desmopressin). In conclusion, pharmacologic blockade of renal P2Y12-R increases urinary concentrating ability by augmenting the effect of AVP on the kidney and ameliorates lithium-induced NDI by potentiating the action of AVP on the CD. This strategy may offer a novel and effective therapy for lithium-induced NDI.
P2Y12受体（P2Y12-R）信号传导通过Gi介导，最终降低细胞内cAMP水平。由于cAMP是精氨酸加压素（AVP）诱导肾集合管（CD）水转运的核心调节因子，我们推测，如果P2Y12-R在CD中表达，它可能在健康状态和肾性尿崩症时的肾脏水代谢中发挥作用。我们在大鼠肾脏中发现了P2Y12-R mRNA表达，并在CD主细胞中对其蛋白和水通道蛋白-2（AQP2）进行了免疫定位。给予硫酸氢氯吡格雷，一种P2Y12-R的不可逆抑制剂，显著增加了Sprague-Dawley大鼠肾脏的尿液浓缩能力和AQP2蛋白。值得注意的是，氯吡格雷并没有改变缺乏AVP的Brattleboro大鼠的尿液浓缩能力。给予氯吡格雷还显著改善了锂诱导的多尿，提高了尿液浓缩能力和AQP2蛋白丰度，并逆转了锂诱导的自由水排泄增加，而没有降低血液或肾脏组织中的锂水平。给予氯吡格雷还增强了锂诱导的尿AVP排泄增加，并抑制了锂诱导的尿硝酸盐/亚硝酸盐（一氧化氮产生）和8-异前列腺素（氧化应激）增加。此外，在大鼠髓质内CD细胞原代培养物中，可逆性拮抗剂PSB-0739对P2Y12-R的选择性阻断增强了AQP2和AQP3 mRNA的表达以及去氨加压素（dDAVP）诱导的cAMP产生。总之，肾脏P2Y12-R的药物阻断通过增强AVP对肾脏的作用来提高尿液浓缩能力，并通过增强AVP对CD的作用来改善锂诱导的肾性尿崩症。这种策略可能为锂诱导的肾性尿崩症提供一种新的有效治疗方法。
