Neural mechanisms governing distribution of cardiac output in an isopod crustacean,Bathynomus doederleini: reflexes controlling the cardioarterial valves

In Bathynomus doederleini all of the cardioarterial valves located at the origin of the lateral arteries are dilated by impulses of lateral cardiac nerves. Tactile stimuli applied to sensillar setae depress impulse activities of the 1st and 5th lateral cardiac nerves. The 1st lateral cardiac nerve controls the valve of the lateral artery which runs to the walking-legs and viscera. The 5th lateral cardiac nerve controls the valve of the lateral artery which runs to the swimmeret muscles. The response indicates that tactile receptor reflexes bring about decreased haemolymph flow to the organs. Augmented swimmeret movements were always accompanied by an increased firing rate in the 5th lateral cardiac nerve. Artificial full protraction of swimmerets simultaneously induced excitation of the 5th lateral cardiac nerve and inhibition of the 1st lateral cardiac nerve. The excitation corresponds to an increase in haemolymph flow to the swimmerets, and the inhibition a decrease in haemolymph flow to walking-legs and viscera. Three kinds of mechanoproprioceptors which were activated by swimmeret movements were found. Two of the mechanoproprioceptors are located at the base of the basipodite. The other mechanoproprioceptor supplies processes to a nerve to the retractor muscles. Activation of three kinds of mechanoproprioceptors, induced by artificial swimmeret protraction, triggered lateral cardiac nerve reflex responses.Abbreviations LA lateral artery - LCN lateral cardiac nerve - RMN nerve to retractor muscles - StR stretch receptor