Structural and functional analogy between insect and human hearts

Abstract- Invertebrate and vertebrate animals (Protostomia and Deuterostomia) are phylogenetically distant groups of animals. Occasionally, there emerge striking structural and functional similarities, which may be of independent polyphyletic origin, although existence of direct evolutionary links cannot be completely ruled out. Recent advances in genetics revealed multiple sets of genes with similar functions in insects (Drosophila) and mammals. Electronic recording methods applied to insects revealed the presence of autonomic, cholinergic, neuroendocrine system (coelopulse), structurally and functionally related to parasympathetic system of vertebrate animals. Moreover, advanced electrocardiographic records on several species of insects (Hyalophora, Manduca, Drosophila), showed that the hearts were regulated by purely myogenic, involuntary mechanism with special pacemaker regulatory nodus in the posterior ampoule of the heart.These findings indicate close physiological analogy with the myogenic, atrioventricular regulatory nodus of the human heart. The heart of Drosophila originates from progenitor cells under influence of similar sets of genes (tinman) that function during development of the human heart. In contrast to tubular insect hearts with peristaltic principle of systolic contractions, adult Drosophila evolved a compact heart chamber (conical ventricle) with atrium, which show certain anatomical and physiological features in common with the human heart. Adult flies (fruitflies, hoverflies) evolved extremely efficient synchronic, not peristaltic, cardiac contractions,simul-taneously propagated over several metameric heart compartments. Vigorous synchronic pumping (4 - 9 Hz) is used for pumping of haemolymph forwards into the head through a narrow thoracic aorta. Examples of electrocardiographic records of insect hearts and the effects of certain cardioactive pharmacological compounds on insect heart will be presented.