1994年，一位“江湖”爬虫学家曾质疑过蛇通过窒息猎物来杀死对方这一官方理论。他认为这不合常理。如果蛇的手段是窒息，那猎物该慢慢地花上几分钟死去，而不是几秒钟。相反，他认为，是蛇卷旋身体所产生的巨大压力导致猎物心脏骤停。研究人员花了20年时间最终证明这个爬虫学家是正确的。为了验证这一假设，一位生理学及生态学家设置了一个实验来记录一只被王蛇（上图所示）缠绕住的小鼠的心率和血压。他们将小鼠弄晕，给它接上电极和导管，然后把它“送”给实验室里饥饿的蟒蛇。研究人员们从旁观察着这条蛇撕咬、缠绕它的猎物，并将它扭成致命的螺旋状。今天发表于《实验生物学杂志》在线版的研究结果表明，短短的6秒内，小鼠的血压即骤降，心率暴涨。心脏紊乱和血液循环被切断（不是缺少空气）是杀死小鼠的主要原因。这种蛇身收缩带来的压迫同时造成小鼠血液中的钾元素猛增，直接引起严重的心脏问题，甚至是心力衰竭而死。但是由于来自蛇的巨大压力阻断了小鼠的血液循环，充满钾的血液很可能没能到达全身。研究人员认为，蛇身收缩引起的钾元素水平的升高可能是蛇捕猎的一个备用计划。这样一来，即使猎物以某种方法脱身，然后血液开始循环，却仍难逃一死，因为它的血中毒了。（来源：生物360）

Snake constriction rapidly induces circulatory arrest in rats

Abstract  As legless predators, snakes are unique in their ability to immobilize and kill their prey through the process of constriction, and yet how this pressure incapacitates and ultimately kills the prey remains unknown. In this study, we examined the cardiovascular function of anesthetized rats before, during and after being constricted by boas (Boa constrictor) to examine the effect of constriction on the prey's circulatory function. The results demonstrate that within 6 s of being constricted, peripheral arterial blood pressure (PBP) at the femoral artery dropped to 1/2 of baseline values while central venous pressure (CVP) increased 6-fold from baseline during the same time. Electrocardiographic recordings from the anesthetized rat's heart revealed profound bradycardia as heart rate (fH) dropped to nearly half of baseline within 60 s of being constricted, and QRS duration nearly doubled over the same time period. By the end of constriction (mean 6.5±1 min), rat PBP dropped 2.9-fold, fH dropped 3.9-fold, systemic perfusion pressure (SPP=PBP−CVP) dropped 5.7-fold, and 91% of rats (10 of 11) had evidence of cardiac electrical dysfunction. Blood drawn immediately after constriction revealed that, relative to baseline, rats were hyperkalemic (serum potassium levels nearly doubled) and acidotic (blood pH dropped from 7.4 to 7.0). These results are the first to document the physiological response of prey to constriction and support the hypothesis that snake constriction induces rapid prey death due to circulatory arrest.

原文链接：http://jeb.biologists.org/content/218/14/2279.full