问题 单项选择题

关于奎尼丁的抗心律失常作用叙述错误的是()

A.降低浦肯野纤维自律性

B.减慢心房、心室和浦肯野纤维传导性

C.延长心房、心室和浦肯野纤维的动作电位时程和有效不应期

D.阻滞钠通道,不影响钾通道

E.对钠通道、钾通道都有抑制作用

答案

参考答案:D

解析:奎尼丁的作用机制主要是抑制钠离子的跨膜作用,其次为抑制钙离子内流,减慢3相钾离子外流。奎尼丁可直接作用于心肌细胞,显著延长心肌细胞动作电位不应期,降低心肌细胞的自律性、兴奋性、传导性和收缩性,特别是对窦房结以外异位节律的作用较强。奎尼丁对心房不应期的延长作用较之对心室的作用明显,对窦房结细胞的动作电位时间无影响或使之延长。奎尼丁作用于房室结折返性心动过速,可阻断折返通路,还可明显延长房室旁道前传的有效不应期和减慢传导速度,因而消除旁道前传现象。

单项选择题
单项选择题

Education is one of the key words of our time. A man, without an education, many of us believe, is an unfortunate victim of unfortunate circumstances deprived of one of the greatest twentieth-century opportunities. Convinced of the importance of education, modern states "invest" in institutions of learning to get back "interest" in the form of a large group of enlightened young men and women who are potential leaders. Education, with its cycles of instruction so carefully worked out, is punctuated by textbooks--those purchasable wells of wisdom--what would civilization be like without its benefits

So much is certain: that we would have doctors and preachers, lawyers and defendants, marriages and births; but our spiritual outlook would be different. We would lay less stress on "facts and figures" and more on a good memory, on applied psychology, and on the capacity of a man to get along with his fellow-citizens. If our educational system were fashioned after its bookless past we would have the most democratic form of "college" imaginable. Among the people whom we like to call savages all knowledge inherited by tradition is shared by all; it is taught to every member of the tribe so that in this respect everybody is equally equipped for life.

It is the ideal condition of the "equal start" which only our most progressive forms of modern education try to reach again. In primitive cultures the obligation to seek and to receive the traditional instruction is binding on all. There are no "illiterates"--if the term can be applied to peoples without a script--while our own compulsory school attendance became law in Germany in 1642, in France in 1806, and in England 1976, and is still non-existent in a number of "civilized" nations. This shows how long it was before we considered it necessary to make sure that all our children could share in the knowledge accumulated by the "happy few" during the past centuries. Education in the wilderness is not a matter of monetary means. All are entitled to an equal start. There is none of the hurry that, in our society, often hampers the full development of a growing personality. There, a child grows up under the ever-present attention of his parents; therefore the jungles and the savages know of no "juvenile delinquency". No necessity of making a living away from home results in neglect of children, and no father is confronted with his inability to "buy" an education for his child.

Notes: juvenile delinquency 青少年犯罪。

The word "interest" in the first paragraph most probably means()

A. pleasure

B. returns

C. share

D. knowledge