Research Centre of the University of Montreal Hospital Centre (CRCHUM), Centre Hospitalier de l'Université de Montréal and Faculty of Pharmacy, Université de Montréal, Montreal, Quebec, Canada.
PLoS One. 2010 Dec 14;5(12):e15666. doi: 10.1371/journal.pone.0015666.
Tissue-specific expression of CYP450s can regulate the intracellular concentration of drugs and explain inter-subject variability in drug action. The overall objective of our study was to determine in a large cohort of samples, mRNA levels and CYP450 activity expressed in the human heart.
CYP450 mRNA levels were determined by RTPCR in left ventricular samples (n = 68) of explanted hearts from patients with end-stage heart failure. Samples were obtained from ischemic and non-ischemic hearts. In some instances (n = 7), samples were available from both the left and right ventricles. A technique for the preparation of microsomes from human heart tissue was developed and CYP450-dependent activity was determined using verapamil enantiomers as probe-drug substrates.
Our results show that CYP2J2 mRNA was the most abundant isoform in all human heart left ventricular samples tested. Other CYP450 mRNAs of importance were CYP4A11, CYP2E1, CYP1A1 and CYP2C8 mRNAs while CYP2B6 and CYP2C9 mRNAs were present at low levels in only some of the hearts analyzed. CYP450 mRNAs did not differ between ischemic and non-ischemic hearts and appeared to be present at similar levels in the left and right ventricles. Incubation of verapamil with heart microsomes led to the formation of nine CYP450-dependent metabolites: a major finding was the observation that stereoselectivity was reversed compared to human liver microsomes, in which the R-enantiomer is metabolized to a greater extent.
This study determined cardiac mRNA levels of various CYP450 isozymes involved in drug metabolism and demonstrated the prevalent expression of CYP2J2 mRNA. It revealed that cardiomyocytes can efficiently metabolize drugs and that cardiac CYP450s are highly relevant with regard to clearance of drugs in the heart. Our results support the claim that drug metabolism in the vicinity of a drug effector site can modulate drug effects.
CYP450 在内脏器官中的表达具有组织特异性，能够调节药物在细胞内的浓度，进而解释药物作用的个体差异。我们的总体目标是在大量样本中确定 CYP450 在人类心脏中的表达及其 mRNA 水平。
采用 RT-PCR 法测定了 68 例终末期心力衰竭患者心脏左心室样本（n=68）的 CYP450 mRNA 水平。样本取自缺血性和非缺血性心脏。在某些情况下（n=7），可以从左心室和右心室获得样本。建立了从人心组织中制备微粒体的技术，并使用维拉帕米对映异构体作为探针药物底物测定 CYP450 依赖性活性。
我们的结果表明，在所有测试的人心左心室样本中，CYP2J2 mRNA 是最丰富的同工酶。其他重要的 CYP450 mRNA 包括 CYP4A11、CYP2E1、CYP1A1 和 CYP2C8 mRNA，而 CYP2B6 和 CYP2C9 mRNA 仅在部分分析的心脏中低水平存在。CYP450 mRNA 在缺血性和非缺血性心脏之间没有差异，并且似乎在左心室和右心室中以相似的水平存在。维拉帕米与心脏微粒体孵育后形成了 9 种 CYP450 依赖性代谢物：一个主要发现是观察到与人类肝微粒体相比，立体选择性发生逆转，其中 R-对映体被代谢的程度更大。
本研究测定了参与药物代谢的各种 CYP450 同工酶的心脏 mRNA 水平，并证明了 CYP2J2 mRNA 的普遍表达。它表明心肌细胞可以有效地代谢药物，并且心脏 CYP450 与心脏中药物的清除密切相关。我们的结果支持了药物效应部位附近的药物代谢可以调节药物作用的观点。
