What differences exist between the heart of an insect and that of a human being? We asked Professor Kared Slama, author of many publications on the subject, who he also invented the electrocardiographic techniques for recording insect heart.The topic is particularly important, because, in recent years, the similarity between the two hearts (human and insect) has caused insects to be used to test cardioactive drugs and cardio-inhibitors

Prof. Kared Slama

Q: Professor Slama, you have published some papers which stated that the cardiovascular system of insects could be used to test cardioactive and cardioinhibitory drugs, by virtue of some similarities between the cardiovascular system of insects and the human one. Can you explain to us what are the similarities?

A: The similarity is striking, insect heart is a segmented tube, the myocardium contracts step-wise segmentally, usually from the tail to the head, but very often it is reversed periodically. The frequency is also quite similar with the human heartbeat, it averages around some 100 pulses per min. However, there are lower limits from 10 beats per min. up to 350(min) at room temperature. Both in humans and insects, the function of the heart is autonomic, purely myogenic, involuntary and the pacemakers are the well known atrioventricular or sinoatrial nodi, in insects it is the posterior pacemaker nodus. In both cases primordial formation of the heart is orchestrated by similar series of genes that are homologous in insect and human genome.

The cardioactive drugs similarly increase the heartbeat rate and the inhibitory drugs decrease the rate like in the human heart.

Q: Since when is science aware of these similarities? What studies have allowed and could allow it to be carried out?

A: The method of testing cardioactive preparations on insects is very practical, the drugs can be injected into the body during measurements. Several years ago I made a Czech patent on using insects for testing, but there was no interest to use it. I have also investigated the effect of temperature, which is also similar, insects have variable temperature, they are cold-blooded creatures. The heartbeat slows down with decreasing temperature, it stops at -5°C.

Q: How has the cardiovascular system of insects evolved, also in relation to the human one?

A: In evolution, vertebrate heart was originally also tubular (Peripatus), human heart actually works on principle of 4 successive segments, insect myocardial segments are usually 10 or 12.