Science2014-06-12 2:01 PM

原油泄漏如何伤害金枪鱼心脏 Crude Oil Impairs Cardiac Excitation-Contraction Coupling in Fish

论文摘要 

一项新的研究显示了为什么来自石油外泄的已知会损害鱼类心脏的有毒化合物会引起这样的损害。该研究所揭示的机制显示了脊椎动物心脏对当今广泛存在于石油中的有毒化合物的易感性。当原油泄漏时,其组分化合物——其中包括多环芳烃(PAHs)——会被释放出来。科学家们已知PAHs对鱼胚胎及发育中的鱼的心脏有害,它会造成鱼心力衰竭及心律失常,但科学家们只是一直不知道其原因。此外,迄今为止大部分的研究都是在模型鱼类中进行的,而不是在那些接触了大规模环境原油泄漏的鱼中进行的,更不要说在那些环境附近孵化的鱼中进行研究了。现在,Fabien Brette及其同事证明,PAHs会造成问题,因为它们会延长幼鱼心肌的动作电位。为了进行他们的研究,研究人员对2种金枪鱼进行了评估,这些鱼已知是在2010年发生深水地平线(DWH)石油泄漏时在墨西哥湾中孵化的。在一个固定该种幼鱼的先进设备中,研究人员对4种原油样本对它们的体外心肌细胞的生理效应的特征进行了描述。他们发现,原油可通过2种机制延长分离的心肌细胞的动作电位。首先,它会与钾离子通道上的在心肌动作电位复极化中起关键作用的位点结合。其次,它会干扰对心脏收缩至关重要的瞬态钙离子释放。总之,这些机制会影响细胞兴奋性的调节,并有可能导致威胁生命的不规则心律。由于Brette等人所描述的机制也可影响其他脊椎动物的心脏,这些结果不仅提出了最近DWH原油泄漏对墨西哥湾内金枪鱼的负面影响,还提出所有的脊椎动物都可能在接触了原油或PAHs之后面临更广泛的影响心脏的风险。

Abstract 

Crude oil is known to disrupt cardiac function in fish embryos. Large oil spills, such as the Deepwater Horizon (DWH) disaster that occurred in 2010 in the Gulf of Mexico, could severely affect fish at impacted spawning sites. The physiological mechanisms underlying such potential cardiotoxic effects remain unclear. Here, we show that crude oil samples collected from the DWH spill prolonged the action potential of isolated cardiomyocytes from juvenile bluefin and yellowfin tunas, through the blocking of the delayed rectifier potassium current (IKr). Crude oil exposure also decreased calcium current (ICa) and calcium cycling, which disrupted excitation-contraction coupling in cardiomyocytes. Our findings demonstrate a cardiotoxic mechanism by which crude oil affects the regulation of cellular excitability, with implications for life-threatening arrhythmias in vertebrates.

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