Liang D C, Keller B J, Misra U K, Thurman R G
Department of Pharmacology, University of North Carolina, Chapel Hill 27599.
Toxicol Appl Pharmacol. 1991 Feb;107(2):344-9. doi: 10.1016/0041-008x(91)90214-y.
2-Ethylhexanol, a metabolite of the commonly used plasticizer di(ethylhexyl)phthalate, was shown to cause toxicity exclusively to periportal regions of the perfused liver (Keller et al., 1990, J. Pharmacol. Exp. Ther. 252, 1355-1360.) To determine whether this toxicity was due to local oxygen tension or to drug delivery, isolated cylinders (plugs) of periportal and pericentral regions of the liver lobule from rats pretreated with phenobarbital were collected with a micropunch following brief perfusion of the organ. Plugs were 0.2 mm wide and 0.5 mm long and weighed between 0.5 and 1 mg each. Following incubation for at least 2 hr in Eagle's medium, they were judged viable based on production of urea at high rates and minimal leakage of lactate dehydrogenase (LDH). Plugs could be cultured for up to 24 hr with minimal loss of activity. Urea synthesis from ammonium chloride (3 mM) by plugs incubated in Krebs-Henseleit buffer equilibrated with 95% O2:5% CO2 was proportional to protein concentration and was linear with time for up to one hour at rates around 75 mumol/g/hr. Incubation of plugs with 2-ethylhexanol (0.1 to 3 mM) diminished urea synthesis in a dose-related manner (half-maximal effect = 0.5 mM). Ethylhexanol also caused extensive cell damage assessed from LDH leakage in incubations at 800 microM O2 but significantly less injury at 200 microM O2. Concomitantly, urea synthesis was inhibited by ethylhexanol by over 80% at 800 microM O2 but less than 50% at 200 microM O2. Plugs isolated from both regions of the liver lobule were affected similarly by ethylhexanol and O2. Taken together, these data indicate that ethylhexanol toxicity is dependent on oxygen tension in isolated sublobular regions of the liver lobule, and therefore it is unlikely that drug delivery can explain the selective injury to periportal regions in studies with the perfused liver.
2-乙基己醇是常用增塑剂邻苯二甲酸二（乙基己基）酯的一种代谢产物，已证明它仅对灌注肝脏的门周区域产生毒性（凯勒等人，1990年，《药理学与实验治疗学杂志》252卷，1355 - 1360页）。为了确定这种毒性是由于局部氧张力还是药物递送所致，在用苯巴比妥预处理过的大鼠肝脏小叶的门周和中央周围区域，通过微型打孔器在器官短暂灌注后收集分离的圆柱体（小块组织）。小块组织宽0.2毫米、长0.5毫米，每个重0.5至1毫克。在伊格尔培养基中孵育至少2小时后，根据尿素的高速产生和乳酸脱氢酶（LDH）的最小泄漏情况判断它们具有活性。小块组织可培养长达24小时，活性损失最小。在与95% O₂:5% CO₂平衡的 Krebs - Henseleit 缓冲液中孵育的小块组织，由氯化铵（3 mM）合成尿素与蛋白质浓度成正比，并且在约75 μmol/g/小时的速率下，长达一小时内与时间呈线性关系。用2-乙基己醇（0.1至3 mM）孵育小块组织会以剂量相关的方式减少尿素合成（半数最大效应 = 0.5 mM）。在800 μM O₂孵育时，通过LDH泄漏评估，乙基己醇还会导致广泛的细胞损伤，但在200 μM O₂时损伤明显较小。同时，在800 μM O₂时，乙基己醇使尿素合成受到超过80%的抑制，但在200 μM O₂时抑制小于50%。从小叶的两个区域分离的小块组织受乙基己醇和O₂的影响相似。综上所述，这些数据表明乙基己醇毒性取决于肝小叶分离的小叶下区域中的氧张力，因此在灌注肝脏研究中，药物递送不太可能解释对门周区域的选择性损伤。
