Temocaprilat, a novel angiotensin-converting enzyme inhibitor, is excreted in bile via an ATP-dependent active transporter (cMOAT) that is deficient in Eisai hyperbilirubinemic mutant rats (EHBR).
Temocaprilat, a novel angiotensin-converting enzyme inhibitor, is excreted in bile via an ATP-dependent active transporter (cMOAT) that is deficient in Eisai hyperbilirubinemic mutant rats (EHBR).
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发表时间：
1997-03
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通讯作者：
Hitoshi Ishizuka;Kumiko Konno;Hideo Naganuma;Kunihiro Sasahara;Yukinori Kawahara;K. Niinuma;Hiroshi Suzuki;Yuichi Sugiyama
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作者：
Hitoshi Ishizuka;Kumiko Konno;Hideo Naganuma;Kunihiro Sasahara;Yukinori Kawahara;K. Niinuma;Hiroshi Suzuki;Yuichi Sugiyama
盐酸替莫普利（Temocapril x HCl）（alpha-（（2S，6 R）-6-[（1 S）-1-ethoxycarbonyl-3-phenyl-propyl]amino-5-oxo-2-（2-thienyl）perhydro-1，4-thiazepin-4-yl）acetic acid hydrochloride）是一种新型的血管紧张素转换酶（ACE）抑制剂前药。与许多其他ACE抑制剂不同，其活性代谢物替莫卡普利拉主要经胆汁排泄。为了研究替莫卡普拉的胆汁排泄机制，我们使用突变型高胆红素血症大鼠（EHBR）进行了体内和体外实验，EHBR的小管多特异性有机阴离子转运蛋白（cMOAT）具有遗传缺陷。在EHBR中静脉给予[14 C]替莫普利x HCl（1.0 mg/kg）后，替莫普利拉的胆汁清除率显著低于Sprague-Dawley大鼠（Sprague-Dawley大鼠为5.00 ml/min/kg，EHBR为0.25 ml/min/kg）。在ATP存在下刺激从Sprague-Dawley大鼠制备的小管膜囊泡（CMV）对替莫卡普拉的摄取，而在EHBR的CMV中观察到很少的刺激。ATP依赖性运输的替莫卡普利拉的初始摄取速率显示饱和动力学;我们获得了1.14 nmol/min/mg蛋白质的表观V（max）值和92.5 μ M的K（m）值。2，4-二硝基苯基-S-谷胱甘肽竞争性抑制替莫卡普拉的ATP依赖性转运，2，4-二硝基苯基-S-谷胱甘肽是cMOAT的典型底物，抑制常数（K（i））为25.8 μ M。CMV摄取2，4-二硝基苯基-S-谷胱甘肽的K（m）值（K（m）= 29.6 μ M）与该K（i）值一致。此外，2，4-二硝基苯基-S-谷胱甘肽的ATP依赖性摄取被替莫卡普利拉以浓度依赖性方式抑制。一些ACE抑制剂的活性形式（贝那普利、西拉普利、地拉普利、依那普利和咪达普利）即使浓度高达200 μ M，也不会影响替莫普利拉转运到CMVs中。这些数据表明，替莫卡普拉通过EHBR缺陷的cMOAT有效地排泄到胆汁中，并且许多其他ACE抑制剂对cMOAT具有低亲和力。
Temocapril x HCl (alpha-((2S,6R)-6-[(1S)-1-ethoxy-carbonyl-3-phenyl-propyl]amino-5-oxo-2- (2-thienyl)perhydro-1,4-thiazepin-4-yl)acetic acid hydrochloride) is a novel prodrug of an angiotensin-converting enzyme (ACE) inhibitor. Unlike many other ACE inhibitors, its pharmacologically active metabolite,temocaprilat, is excreted predominantly in bile. To investigate the mechanism for the biliary excretion of temocaprilat, we performed in vivo and in vitro experiments using mutant Eisai hyperbilirubinemic rats EHBR) whose canalicular multispecific organic anion transporter (cMOAT) is hereditarily defective. Biliary clearance of temocaprilat after i.v. administration of [14C]temocapril x HCl (1.0 mg/kg) in EHBR was significantly lower than that in Sprague-Dawley rats (5.00 ml/min/kg for Sprague-Dawley rats vs. 0.25 ml/min/kg for EHBR). The uptake of temocaprilat into canalicular membrane vesicles (CMVs) prepared from Sprague-Dawley rats was stimulated in the presence of ATP, whereas little stimulation was observed in CMVs from EHBR. The initial uptake rate of ATP-dependent transport of temocaprilat showed saturation kinetics; we obtained an apparent V(max) value of 1.14 nmol/min/mg protein and a K(m) value 92.5 microM. ATP-dependent transport of temocaprilat was competitively inhibited by 2,4-dinitrophenyl-S-glutathione, a typical substrate for cMOAT with an inhibition constant (K(i)) of 25.8 microM. The K(m) value for the uptake of 2,4-dinitrophenyl-S-glutathione into CMVs (K(m) = 29.6 microM) was consistent with this K(i) value. In addition, the ATP-dependent uptake of 2,4-dinitrophenyl-S-glutathione was inhibited by temocaprilat in a concentration-dependent manner. Active forms of some ACE inhibitors (benazepril, cilazapril, delapril, enalapril and imidapril) did not affect the transport of temocaprilat into CMVs even at concentrations as high as 200 microM. These data suggest that temocaprilat is effectively excreted in bile via cMOAT that is deficient in EHBR and that many of other ACE inhibitors have low affinity for cMOAT.