Advances in Medicine and Biology. Volume 43

0376139 - BC 2013 RIV US eng M - Část monografie knihy
Sláma, Karel
Neuromuscular paralysis induced in insect larvae by the proteinic venom of a parasitic wasp.
Advances in Medicine and Biology. Volume 43. New York: Nova Science Publishers, 2012 - (Berhardt, L.), s. 195-212. ISBN 978-1-62100-889-7
Výzkumný záměr: CEZ:AV0Z50070508
Klíčová slova: neuromuscular paralysis
Kód oboru RIV: ED - Fyziologie

Larvae of the greater wax moth (Galleria mellonella), stung by a tiny 2.5 mm long Habrobracon hebetor wasp, become immobilised within a few minutes and remain completely paralysed for several weeks. Paralysed larvae are absolutely motionless, flaccid, without internal pressure, serving as a source of food for the parasite. The venom is a relatively large proteinic molecule, its size has been estimated by various authors from 17 to 73 kDa, and the largest fraction has been partly sequenced. The mode of action is generally ascribed to the inhibition of neuromuscular transmission. Purely myogenic systems driven by depolarisation potentials of the muscle or myocardium cells (heart, intestine) or junctional potencials of the sympathetic nerves (glands, excretory organs), remain intact and fully functional. Using recently invented, touch-free electrocardiographic (ECG) techniques, we found that the heartbeat of paralysed larvae was regulated by a purely myogenic mechanism with a pacemaker nodus in the posterior compartment of the heart (analogous to the atrioventricular or sinoatrial nodi of the human heart). The ECG records of paralysed larvae revealed continuous, unidirectional propagation of the systolic cardiac contractions in the forward direction. The rate of heartbeat was proportionally diminished as a function of decreasing temperature, until it was completely arrested at temperatures of -2 to -5°C. Under the total absence of body movements, the heart of paralysed larvae was an ideal model for testing cardioactive drugs. It responded very well to selected cardioinhibitory effects of Ca2+ ion blockers (verapamil) and also to the cardiostimulating effects of digitoxine or nitrates (similarly to the responses of a human heart).
Trvalý link: http://hdl.handle.net/11104/0216796