英语听力文摘 English Digest 515、失去知觉之后

 　　Out for the Count

 

　　失去知觉之后

 

　　If you’ve ever had major surgery, you probably remember lying down and waking up–but nothing in between. Thanks to the anesthesiologist, during the actual surgery you were out of it: immobilized and insensitive to pain. But until recently scientists had little understanding of how anesthetics actually work on the cellular² level.

 

　　That’s changed thanks to recent experiments performed by researchers at the University of Zurich, in Switzerland. They knew that anesthetics caused pain receptors in the brain to turn off by acting³ like most drugs do: anesthetizing drugs attach to particular sites on nerve cells and turn them off. The question was, where on nerve cells do these drugs attach?

 

　　Nerve cell membranes⁴ have receptors for different kinds of chemicals produced by the brain. Gamma-amino butyric acid, or GABA, for example, is a chemical that shuts down nerve cells. The hypothesis was that general anesthesia works by binding⁵ to GABA receptors on a nerve cell, thereby⁶ activating⁷ the receptor and instructing the cell to shut down. So it made sense for the Zurich researchers to focus on GABA receptors.

 

　　To do this they worked with mice that had been genetically⁸ engineered to have nerve cells with GABA receptors that wouldn’t respond to anesthetics. And sure enough, when such mice were given anesthetic¹ drugs they weren’t nearly as immune to pain as regular mice that had also been given pain-blocking drugs. Clearly, GABA receptor sites on nerve cells are part of what allows anesthetics to do their job.

 

　　While the Zurich experiment fills in only one piece of the puzzle, it is an important step towards learning how these amazing drugs work, and how to make them even better.

 

　　如果你曾经做过重大手术，那么你肯定只记得躺下去和醒来这么2个动作，而其间过程是浑然不知的。多亏了麻醉师，你才能在手术中无知觉地度过：不能动弹，也感觉不到疼痛。但是直到最近科学家们才多少了解到麻醉药是如何在细胞层面上工作的。

 

　　还得感谢瑞士苏黎世大学的研究员们最近做的实验，这一困惑才得以解开。他们弄清楚了麻药是通 过关闭大脑中的疼痛接收器才使人感觉不到疼痛，原理跟大多数药物一样：麻药附着在神经细胞上某个特殊位置，然后将感知功能关闭。问题是，麻药到底附着在什么位置呢？

 

　　神经细胞膜有多个接收器来识别大脑产生的不同类别的化学物质。例如γ-氨基丁酸，或者简写为GABA，就是可以关闭神经细胞感知功能的化学物质。假设全身麻醉是将麻药和在神经细胞上的GABA接收器绑定在一起，从而激活接收器，然后再传达闭接收功能的指令关的。这样的假设就使苏黎世大学的研究员们明白，集中精力研究GABA接收器是关键所在。

 

　　为了证明这点，他们用基因改造过的老鼠做实验，这种老鼠身上的 GABA接收器对麻药免疫。毫无疑问，这样的老鼠在使用了麻药后，比起正常的用了麻药的老鼠，疼痛感几乎没有降低。显然位于神经细胞上的GABA接收器是让麻药起作用的原因之一。

1 anesthetic   

n.麻醉剂，麻药；adj.麻醉的，失去知觉的

参考例句：

• He was given a general anesthetic.他被全身麻醉。
• He was still under the influence of the anesthetic.他仍处在麻醉状态。

2 cellular   

adj.移动的；细胞的，由细胞组成的

参考例句：

• She has a cellular telephone in her car.她的汽车里有一部无线通讯电话机。
• Many people use cellular materials as sensitive elements in hygrometers.很多人用蜂窝状的材料作为测量温度的传感元件。

3 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

4 membranes   

n.（动物或植物体内的）薄膜( membrane的名词复数 )；隔膜；（可起防水、防风等作用的）膜状物

参考例句：

• The waste material is placed in cells with permeable membranes. 废液置于有渗透膜的槽中。 来自辞典例句
• The sarcoplasmic reticulum is a system of intracellular membranes. 肌浆网属于细胞内膜系统。 来自辞典例句

5 binding   

有约束力的，有效的，应遵守的

参考例句：

• The contract was not signed and has no binding force. 合同没有签署因而没有约束力。
• Both sides have agreed that the arbitration will be binding. 双方都赞同仲裁具有约束力。

6 thereby   

adv.因此，从而

参考例句：

• I have never been to that city,,ereby I don't know much about it.我从未去过那座城市，因此对它不怎么熟悉。
• He became a British citizen,thereby gaining the right to vote.他成了英国公民，因而得到了投票权。

7 activating   

活动的，活性的

参考例句：

• "I didn't say we'd got to stop activating the masses! “我并没说就此不发动！ 来自子夜部分
• Presumably both the very small size and activating influence of fluorine atoms contribute to this exception. 这大概是由于氟原子半径小和活性高这两个原因的影响，氟原子对这种例外做出了贡献。

8 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物