OXYLAB - Mitochondrial Physiology Lab: Charles University, 3rd Faculty of Medicine and FNKV University Hospital, Prague, Czech Republic.
Department of Orthopaedics and Traumatology, Charles University, 3rd Faculty of Medicine and FNKV University Hospital, Prague, Czech Republic.
PLoS One. 2019 Oct 4;14(10):e0217254. doi: 10.1371/journal.pone.0217254. eCollection 2019.
Propofol causes a profound inhibition of fatty acid oxidation and reduces spare electron transfer chain capacity in a range of human and rodent cells and tissues-a feature that might be related to the pathogenesis of Propofol Infusion Syndrome. We aimed to explore the mechanism of propofol-induced alteration of bioenergetic pathways by describing its kinetic characteristics.
We obtained samples of skeletal and cardiac muscle from Wistar rat (n = 3) and human subjects: vastus lateralis from hip surgery patients (n = 11) and myocardium from brain-dead organ donors (n = 10). We assessed mitochondrial functional indices using standard SUIT protocol and high resolution respirometry in fresh tissue homogenates with or without short-term exposure to a range of propofol concentration (2.5-100 μg/ml). After finding concentrations of propofol causing partial inhibition of a particular pathways, we used that concentration to construct kinetic curves by plotting oxygen flux against substrate concentration during its stepwise titration in the presence or absence of propofol. By spectrophotometry we also measured the influence of the same propofol concentrations on the activity of isolated respiratory complexes.
We found that human muscle and cardiac tissues are more sensitive to propofol-mediated inhibition of bioenergetic pathways than rat's tissue. In human homogenates, palmitoyl carnitine-driven respiration was inhibited at much lower concentrations of propofol than that required for a reduction of electron transfer chain capacity, suggesting FAO inhibition mechanism different from downstream limitation or carnitine-palmitoyl transferase-1 inhibition. Inhibition of Complex I was characterised by more marked reduction of Vmax, in keeping with non-competitive nature of the inhibition and the pattern was similar to the inhibition of Complex II or electron transfer chain capacity. There was neither inhibition of Complex IV nor increased leak through inner mitochondrial membrane with up to 100 μg/ml of propofol. If measured in isolation by spectrophotometry, propofol 10 μg/ml did not affect the activity of any respiratory complexes.
In human skeletal and heart muscle homogenates, propofol in concentrations that are achieved in propofol-anaesthetized patients, causes a direct inhibition of fatty acid oxidation, in addition to inhibiting flux of electrons through inner mitochondrial membrane. The inhibition is more marked in human as compared to rodent tissues.
丙泊酚会显著抑制脂肪酸氧化，并降低多种人体和啮齿动物细胞及组织中线粒体电子传递链的备用能力——这一特征可能与丙泊酚输注综合征的发病机制有关。本研究旨在通过描述其动力学特征来探讨丙泊酚引起的能量代谢途径改变的机制。
我们从 Wistar 大鼠（n = 3）和人类供体（n = 11）的髋部手术患者股外侧肌和 n = 10）的脑死亡器官捐献者的心肌中获得骨骼肌和心肌样本。我们使用标准的 SUIT 方案和高分辨率呼吸测量法，在新鲜组织匀浆中评估线粒体功能指标，其中包括或不包括短期暴露于一系列丙泊酚浓度（2.5-100 μg/ml）。在找到导致特定途径部分抑制的丙泊酚浓度后，我们使用该浓度通过在存在或不存在丙泊酚的情况下，逐步滴定氧流量与底物浓度来构建动力学曲线。通过分光光度法，我们还测量了相同丙泊酚浓度对分离呼吸复合物活性的影响。
我们发现，与大鼠组织相比，人类肌肉和心脏组织对丙泊酚介导的能量代谢途径抑制更为敏感。在人类匀浆中，丙泊酚抑制肉碱棕榈酰转移酶 I 活性所需的浓度低于电子传递链能力降低所需的浓度，这表明丙泊酚抑制 FAO 的机制不同于下游限制或肉碱棕榈酰转移酶 1 抑制。复合物 I 的抑制特征是 Vmax 明显降低，与抑制的非竞争性性质一致，其模式与复合物 II 或电子传递链能力的抑制相似。在高达 100 μg/ml 的丙泊酚浓度下，复合物 IV 既没有被抑制，也没有增加线粒体内膜的通透性。如果通过分光光度法单独测量，丙泊酚 10 μg/ml 不会影响任何呼吸复合物的活性。
在丙泊酚麻醉患者达到的浓度下，丙泊酚会直接抑制脂肪酸氧化，除了抑制电子通过线粒体内膜的流动，此外还会在人体骨骼肌和心肌匀浆中引起这种作用。与啮齿动物组织相比，这种抑制在人类组织中更为明显。
