Biological Center of Czech Academy of Sciences, Institute of Entomology, Drnovská 507, Prague, Czech Republic.
J Insect Physiol. 2011 Feb;57(2):251-9. doi: 10.1016/j.jinsphys.2010.11.004. Epub 2010 Nov 24.
Larvae of the greater waxmoth (Galleria mellonella) become paralysed by the venom of the braconid wasp (Habrobracon hebetor) a few minutes after intoxication. The profound neuromuscular paralysis, which may last for several weeks, includes all somatic muscles that are innervated through neuromuscular transmission. The peristaltic contractions of the heart and intestine, which are regulated by the depolarisation potentials of the myocardium or intestinal epithelial muscles, remain unaffected and fully functional. Heartbeat patterns and intestinal pulsations were monitored in the motionless, paralysed larvae by means of advanced electrocardiographic recording methods (contact thermography, pulse-light optocardiography). The records revealed more or less constant cardiac pulsations characterised by 20-25 systolic contractions per minute. The contractions were peristaltically propagated in the forward (anterograde) direction, with a more or less constant speed of 10mm per second (23-25°C). Additional electrocardiographic investigations on larvae immobilised by decapitation revealed the autonomic (brain independent) nature of heartbeat regulation. Sectioning performed in the middle of the heart (4th abdominal segment) seriously impaired the pacemaker rhythmicity and slowed down the rate of heartbeat in the anterior sections. By contrast, the functions of the posterior compartments of the disconnected heart remained unaffected. These results confirmed our previous conclusions about the existence of an autonomic, myogenic, pacemaker nodus in the terminal part of an insect heart. They show an analogy to the similar myogenic, sinoatrial or atrioventricular nodi regulating rhythmicity of the human heart. Peristaltic contractions of the intestine also represent a purely myogenic system, which is fully functional in larvae with complete neuromuscular paralysis. Unlike the constant anterograde direction of the heartbeat, intestinal peristaltic waves periodically reversed anterograde and retrograde directions. A possibility that the functional similarity between insect and human hearts may open new avenues in the field of comparative cardiology has been discussed.
大蜡螟（Galleria mellonella）的幼虫在中毒几分钟后会被茧蜂（Habrobracon hebetor）的毒液麻痹。这种深度的神经肌肉麻痹可能持续数周，包括所有通过神经肌肉传递来支配的躯体肌肉。心脏和肠道的蠕动收缩是通过心肌或肠上皮肌肉的去极化电位来调节的，不受影响，且功能完全正常。通过先进的心电图记录方法（接触热成像、脉冲光光电心图），监测了静止、麻痹的幼虫中不动的、麻痹的心脏和肠道的搏动模式。记录显示，或多或少有规律的心脏搏动，每分钟有 20-25 次收缩。收缩以或多或少恒定的速度（23-25°C 时为每秒 10 毫米）向前（顺行）传播。对通过断头术固定的幼虫进行的额外心电图研究表明，心跳调节是自主的（与大脑无关）。在心脏中部（第 4 个腹部段）进行的切割严重损害了起搏器的节律性，并使前部分的心跳速度减慢。相比之下，断开的心脏后部隔室的功能不受影响。这些结果证实了我们之前关于在昆虫心脏末端存在自主、肌源性、起搏器结的结论。它们显示出与调节人类心脏节律的类似的肌源性、窦房结或房室结的类似性。肠道的蠕动收缩也是一个完全由肌肉驱动的系统，在完全神经肌肉麻痹的幼虫中完全正常工作。与心跳的恒定顺行方向不同，肠道蠕动波周期性地反转顺行和逆行方向。昆虫和人类心脏之间的功能相似性可能为比较心脏病学领域开辟新途径的可能性已经被讨论。
