Bimodal distribution of renal cytochrome P450 3A activity in humans.
Bimodal distribution of renal cytochrome P450 3A activity in humans.
复制标题
DOI：
--
复制
发表时间：
1996-07
影响因子：
3.6
通讯作者：
B. Haehner;J. Gorski;M. Vandenbranden;S. Wrighton;S. K. Janardan;P. Watkins;S. Hall
中科院分区：
文献类型：
--
作者：
B. Haehner;J. Gorski;M. Vandenbranden;S. Wrighton;S. K. Janardan;P. Watkins;S. Hall
已经提出，通过CYP 3A将皮质醇过度肾内转化为6 β-羟基皮质醇可能介导肾小管钠重吸收增加，导致轻度体积扩张状态和盐敏感性高血压的临床表型。因此，我们使用1 '-羟基咪达唑仑（1'-OHM）的形成作为原型CYP 3A催化反应，表征了人肾脏微粒体库中的CYP 3A活性。代谢物形成的最大速率发生在咪达唑仑浓度为12.5-50 μ M时;较高的浓度导致显著的底物抑制。在12.5 μ M咪达唑仑时，27个肾脏中有4个显示出相对较高的平均+/-标准差1 '-OHM形成率（184.0 +/- 14.4 pmol/hr/mg），而其余23个样本的平均形成率为（10.1 +/- 6.4 pmol/hr/mg）。三乙酰竹桃霉素和抗CYP 3A抗体分别抑制咪达唑仑羟基化53%和57%。通过免疫印迹法测定的CYP 3A 5含量与1 '-OHM形成率之间的相关性较高（r2 = 0.84，24次实验）。以特异性寡核苷酸为引物，通过聚合酶链反应测定CYP 3A 3、CYP 3A 4、CYP 3A 5和CYP 3A 7相应mRNA的表达。检查的所有肾脏（25项实验）均表达CYP 3A 5蛋白，并含有相应的CYP 3A 5 mRNA。在40%的肾脏样本中检测到CYP 3A 4 mRNA，70%含有可检测CYP 3A 4 mRNA的肾脏样本也表达可检测水平的相应蛋白。因此，与CYP 3A 4普遍表达的肝组织相反，CYP 3A 5是CYP 3A家族在肾组织中普遍表达的成员。酶活性和蛋白质含量的分布表明双峰性，并可能代表在选定人群中诱导CYP 3A 5和/或遗传确定的器官特异性表达模式。
It has been proposed that excessive intrarenal conversion of cortisol to 6 beta-hydroxycortisol by CYP3A may mediate increased tubular reabsorption of sodium, leading to a state of mild volume expansion and the clinical phenotype of salt-sensitive hypertension. Therefore, we characterized CYP3A activity in a bank of microsomes from human kidneys using the formation of 1'-hydroxymidazolam (1'-OHM) as a prototypical CYP3A-catalyzed reaction. Maximal rates of metabolite formation occurred at midazolam concentrations of 12.5-50 microM; higher concentrations resulted in dramatic substrate inhibition. At 12.5 microM midazolam, 4 of 27 kidneys exhibited relatively high mean +/- standard deviation 1'-OHM formation rate (184.0 +/- 14.4 pmol/hr/mg) compared with the remaining 23 samples, which had a mean formation rate of (10.1 +/- 6.4 pmol/hr/mg). Triacetyloleandomycin and anti-CYP3A antibody inhibited midazolam hydroxylation by 53% and 57%, respectively. The correlation between CYP3A5 content, determined through immunoblotting, and 1'-OHM formation rate was high (r2 = 0.84, 24 experiments). The expressions of mRNA corresponding to CYP3A3, CYP3A4, CYP3A5, and CYP3A7 were determined through polymerase chain reaction with specific oligonucleotides as primers. All kidneys examined (25 experiments) expressed CYP3A5 protein and contained the corresponding CYP3A5 mRNA. CYP3A4 mRNA was detected in 40% of the kidney samples, and 70% of those that contained detectable CYP3A4 mRNA also expressed detectable levels of the corresponding protein. Therefore, in contrast to hepatic tissue, in which CYP3A4 is universally expressed, CYP3A5 is the ubiquitously expressed member of the CYP3A family in renal tissue. The distribution of enzyme activity and protein content suggests bimodality and may represent induction of CYP3A5 in a select population and/or a genetically determined organ-specific pattern of expression.