Silomon M, Pizanis A, Larsen R, Rose S
Department of Trauma, Hand and Reconstructive Surgery, University of Saarland, Homburg, 66421, Germany.
J Surg Res. 1997 Oct;72(2):101-6. doi: 10.1006/jsre.1997.5171.
A role of the potent proinflammatory Ca2+ agonist platelet-activating factor (PAF) on hepatocellular Ca2+ homeostasis and oxidant injury was investigated, since Ca2+ dysregulation has been demonstrated as a pivotal pathomechanism causing hepatic dysfunction during hemorrhagic or septic shock. In anesthetized male Sprague-Dawley rats, blood was withdrawn to a mean arterial blood pressure of 40 mm Hg for 60 min. Rats were resuscitated with 60% of shed blood and threefold the shed blood volume of lactated Ringers' (shock group). After 60 min of resuscitation, hepatocytes were isolated by portal collagenase perfusion. Hepatocellular Ca2+ uptake (Caup2+), initial rate of Ca2+ influx (Cain2+), and membrane Ca2+ flux (Caflux2+) were determined using 45Ca2+ incubation techniques. Hepatocyte oxidant injury was fluorometrically determined by thiobarbituric acid reactive substances. Caup2+ (3.37 +/- 0.15 vs. 2. 53 +/- 0.08 nmole Ca2+/mg protein), Cain2+ (0.42 +/- 0.1 vs. 0.27 +/- 0.02 nmole Ca2+/mg protein/min), and Caflux2+ (31.3 +/- 4.3 vs. 16.9 +/- 2.4 pmole Ca2+/mg/min) significantly increased in the untreated shock group compared to untreated sham-operated rats (P < 0.05). The specific PAF receptor antagonist BN52021 given 5 min before (5 mg/kg b.w.) and continuously during resuscitation (5 mg/kg/hr) significantly reduced Caup2+ in the shock group (2.73 +/- 0.2; P < 0.01) and prevented hepatocyte lipid peroxidation (shock: 91.9 +/- 1; shockBN52021: 66.7 +/- 2 nmole/mg wet weight; P < 0.01). These data suggest that platelet-activating factor plays a pivotal role in promoting hepatocyte Ca2+ overload during hemorrhagic shock by releasing Ca2+ agonistic mediators and inducing oxidative membrane alterations both of which are capable of enhancing cellular Ca2+ influx.
鉴于钙离子调节异常已被证明是出血性或感染性休克期间导致肝功能障碍的关键病理机制，研究了强效促炎钙离子激动剂血小板活化因子（PAF）对肝细胞钙离子稳态和氧化损伤的作用。在麻醉的雄性Sprague-Dawley大鼠中，将血压降至平均动脉血压40 mmHg并维持60分钟。用失血量的60%和三倍失血量的乳酸林格氏液对大鼠进行复苏（休克组）。复苏60分钟后，通过门静脉胶原酶灌注分离肝细胞。使用45Ca2+孵育技术测定肝细胞钙离子摄取（Caup2+）、钙离子流入初始速率（Cain2+）和膜钙离子通量（Caflux2+）。通过硫代巴比妥酸反应性物质荧光法测定肝细胞氧化损伤。与未处理的假手术大鼠相比，未处理的休克组中Caup2+（3.37±0.15对2.53±0.08 nmol Ca2+/mg蛋白质）、Cain2+（0.42±0.1对0.27±0.02 nmol Ca2+/mg蛋白质/分钟）和Caflux2+（31.3±4.3对16.9±2.4 pmol Ca2+/mg/分钟）显著增加（P<0.05）。在复苏前5分钟给予特异性PAF受体拮抗剂BN52021（5 mg/kg体重）并在复苏期间持续给予（5 mg/kg/小时），可显著降低休克组的Caup2+（2.73±0.2；P<0.01）并预防肝细胞脂质过氧化（休克组：91.9±1；休克+BN52021组：66.7±2 nmol/mg湿重；P<0.01）。这些数据表明，血小板活化因子在出血性休克期间通过释放钙离子激动介质和诱导氧化膜改变在促进肝细胞钙离子超载中起关键作用，这两者均能够增强细胞钙离子流入。
