CONTRIBUTIONS TO PHYSIOLOGY OF THE ANTENNA-HEART IN PERIPLANETA-AMERICANA (L.) (BLATTODEA, BLATTIDAE)

An accessory pulsatile organ of an open circulatory system in insects supplying the antennae with haemolymph was investigated. The rhythm of this so-called antenna-heart is generated by a myogenic automatism an d can be neuronally influenced via the nervus cardioantennalis. The ac tion potentials of the muscle fibres show typical pre-depolarization a nd mostly no overshoot. A specific membrane resistance (R-m) of about 660 Omega cm(-2) was calculated for the fibres. Some electrical coupli ng between the muscle fibres is presumed for synchronization of any my ogenically triggered heart beat which could actually be proved experim entally by current injection in the antenna-heart. However, intercalat ed disks or gap junctions could not be found. Nevertheless, a good cou pling factor (U-2/U-1) between all fibres was demonstrated by parallel recordings and can be well described by a conductance model according to fibre topology. (C) 1997 Elsevier Science Ltd. All rights reserved .