Repartition biologique des guanidines substituees chez des vers terrestres et d'eau douce (oligochetes, hirudinees, turbellaries) recoltes en hongrie

Anaerobic metabolism in the leech (Hirudo medicinalis L.): direct and indirect calorimetry during severe hypoxia

Anaerobic metabolism in the limnic annelid Hirudo medicinalis L. was investigated by direct and indirect calorimetry. During long-term severe hypoxia, the rate of heat dissipation was reduced up to 13% of the aerobic rate. At the same time, the rate of ATP turnover was reduced to about 30% of the aerobic rate, indicating that metabolic depression is an important mechanism to ensure survival of the leech during environmental anaerobiosis. Heat dissipation during hypoxia was monitored under two experimental conditions, favouring either concomitant hypocapnia (continuous N2 bubbling) or hypercapnia (self-induced hypoxia). The reduction in heat dissipation during hypocapnic hypoxia was less pronounced than during hypercapnic hypoxia, indicating that the different experimental conditions may influence anaerobic metabolism and the extent of metabolic depression. Biochemical analysis of known anaerobic substrates and endproducts provided the basis for indirect calorimetry during self-induced hypoxia. From changes in metabolites, the expected heat dissipation was calculated for initial (0-8 ,h) and long-term severe hypoxia (8-72 h). During the initial period, the calculated heat dissipation fully accounted for direct calorimetric determination. During long-term hypoxia, only 71% of the measured heat production could be explained from biochemical analysis of metabolites. Therefore, an additional unknown endproduct cannot be excluded, especially when anaerobic ammonia production and analysis of the carbohydrate balance are considered.

Alterations in polyamine levels of nematode, earthworm, leech and planarian during regeneration, temperature and osmotic stresses

Free-living nematodes, Caenorhabditis elegans and Dorylaimus fodori, contain putrescine and spermidine. Putrescine, spermidine and spermine occur in the parasitic Nematoda, Ascaris suum, Anisakis simplex and Dirofilaria immitis. Earthworms, Eisenia foetida, Tubifex hattai and Pheretima communissima and the leech, Hirudo nipponia (belonging to Annelida) and the planarian, Dugesia japonica (belonging to Platyhelminthes) contain homospermidine and spermine in addition to putrescine and spermidine. Regenerated heads of E. foetida and D. japonica are rich in putrescine indicating the stimulation of its synthesis during regeneration. Putrescine and spermidine levels temporarily increase after heat shock in C. elegans, E. foetida and D. japonica and cold shock and hypertonic osmotic shock treatments in D. japonica.

Recovery after anaerobic metabolism in the leech (Hirudo medicinalis L.)

Medicinal leeches (Hirudo medicinalis L.) responded to self-induced hypoxia (72 h) with typical anaerobic metabolism characterized by a decrease in adenylate energy charge, utilization of the substrates glycogen and malate, and accumulation of the main anaerobic end-products succinate and propionate. Propionate was also excreted into the medium. Ammonia excretion was suppressed. Aerobic recovery resulted in a profound O2 debt. Resynthesis of ATP was completed within 30 min. Disposal of succinate and restoring of malate required 2-3 h, and clearance of propionate and recharging of glycogen 6-12 h. Ammonia excretion did not exceed normoxic rates and excretion of propionate during recovery accounted for only 10% of total propionate accumulated during hypoxia. It is postulated that the clearance of succinate and propionate involves oxidation but also resynthesis of malate and glycogen. During hypoxia and recovery blood osmolality remained constant. The Na+ and Cl- ion concentrations in blood, the decrease of which was nearly equimolar during hypoxia, were re-established following different time-courses. Na+ concentration returned to normoxic levels after 2-3 h. The delayed increase in Cl- concentration, however, correlating with 6-12 h necessary to clear blood propionate, is interpreted as an anion regulating effect.