Authors:
Karel Sláma
1
and
Radek Aulicky
2
Affiliations:
1
Czech Academy of Sciences, Czech Republic
;
2
Crop Research Institute, Czech Republic
Keyword(s):
Peristaltic Myocardial Contractions, Tubular Heart, Heartbeat Reversal, Myogenic Heartbeat, Pacemaker Nodus, Neuromuscular Paralysis.
Related
Ontology
Subjects/Areas/Topics:
Cardiovascular Imaging and Cardiography
;
Cardiovascular Technologies
;
Electrocardiography
;
Health Engineering and Technology Applications
Abstract:
The primordial formation of insect and human hearts is orchestrated by similar sets of genes. The rhythmi city of purely myogenic, peristaltic myocardial contractions of insect heart is determined by a posterior pace-maker nodus, which is analogous to sinoatrial or atrioventricular pacemaker nodi of the human heart. Insects are very mobile animals; there are vigorous neuromuscular contractions and extracardiac pulsations in haemocoelic pressure, which may seriously interfere with recordings of the heartbeat. This problem was solved by using larvae of the waxmoth, whose neuromuscular functions were totally paralysed by proteinaceous venom of the parasitic braconid wasp. The paralysed larvae survived motionless for 3 to 4 weeks, however, the regular myogenic pulsations of the heart and intestine, regulated by depolarisation potentials of the myocardial or intestinal cells, remained fully preserved. The paralysed larvae of the waxmoth are ideal object for cardiological research. By mean
s of a touch-free, optoelectronic method we found that the larval heart exhibited uninterrupted, forward-oriented (anterograde), peristaltic waves of systolic myocardial contractions, propagated with a rate similar to that of the human heart (at 37°C). Extensive screening of various cardioactive drugs revealed that the larval heartbeat, like the human heartbeat, was sensitive to chronotropic action of digitoxine and the nitrates or cardiomoderating action of verapamil.
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