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

Abstract

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.Key words Cardioarterial valve -Valve dilator nerve 9 Haemolymph distribution 9 Mechanoproprioceptor 9 Mechanosensory reflexes Abbreviations LA lateral artery" LCNlateral cardiac nerve. RMNnerve to retractor muscles. StRstretch receptor

Allatostatin modulates skeletal muscle performance in crustaceans through pre‐ and postsynaptic effects

“…N1 and N2 originate in the ganglion and supply the extrinsic and intrinsic muscles of the pereiopods. They also contain the sensory afferents from the body wall, endopodite and exopodite ( Okada & Kuwasawa 1995, shown for the isopod species Bathynomus doederleini ). N3 branches posterolaterally from the connective.…”

Neurohormonal and glutamatergic neuronal control of the cardioarterial valves in the isopod crustaceanBathynomus doederleini

“…When swimmerets beat strongly, impulse rate always increased in the axon of LCN5 to the valve of LA5, which supplies haemolymph to swimmeret muscles. Impulse rate decreased in the first lateral cardiac nerve, the dilator of the valve of the first lateral artery, which supplies haemolymph to walking legs (Okada and Kuwasawa, 1995). We observed that when impulse rates of valve inhibitory and valve excitatory axons increased during movements of the oral appendages, the haemolymph supply was increased to the muscles of the oral appendages through the ALA.…”

“…For example, during swimming, impulse rates of the fifth lateral cardiac nerve (LCN5) and of the valve excitatory axon increase, while the impulse rate of the first lateral cardiac nerve (LCN1) decreases (Tanaka et al, 1996;Fujiwara-Tsukamoto et al, 1992;Okada and Kuwasawa, 1995). These changes in impulse rate of the valve nerves cause an increase of haemolymph flow into LA5, which supplies haemolymph to the swimmeret muscle.…”

Physiological Saline Suitable for the Marine Isopod Crustacean Bathynomus doederleini

“…For physiological study of the giant marine isopod Bathynomus, sea water (SW) has been used as saline (Kihara and Kuwasawa, 1984;Tanaka et al (1992); Fujiwara-Tsukamoto et al, 1992;Okada and Kuwasawa, 1995). In natural SW, the isolated Bathynomus heart continued regular heartbeats for more than twelve hours, stimulation of cardiac nerves was effective and neuromuscular junctional potentials could be recorded intracellularly from the cardioarterial valves (Kihara and Kuwasawa, 1984).…”