Abstract Extraintestinal calcium influxes were measured in the killifish, Fundulus heteroclitus , in solutions with different calcium concentrations, from distilled water level (near 0) to seawater level (approximately 12 mM). The extraintestinal influx is modified by the concentration of calcium in the medium during the adaptive period. In freshwater‐adapted fish, calcium depletion resulted in an increase in calcium uptake. Such an adaptation was not observed in calcium‐depleted fish in artificial calcium‐deficient seawater. Calcium depletion in either medium seems to increase the calcium permeability. No correlation was found between Ca‐ATPase activity in the gill tissue and calcium uptake.
Young male rats, Wistar CF strain, weighing about 100 g, were fed during 14 days with a well-balanced diet, but containing either 275 p.p.m. nabame, either 600 p.p.m. thirame or 3 600 p.p.m. zinebe. The animals given the non-contaminated diet were the controls. On the evening before the experiment, they were all fasted and some of them, forced to walk during 18 hours in a restraint wheel. On the morning of the experiment, some of the rats which have not been working were placed in a cold room at + 4 degrees C, and some others were given an i.p. injection of 2,6 g glucose per kg body weight. The animals were then killed, those that received the glucose treatment 30 mn after the injection, the cold-exposed rats 90 mn after the beginning of their exposure. The redox and energy potentials of the liver tissue were determined after the enzymatic assay of the following liver metabolites : lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, ATP, ADP, AMP, inorganic phosphate. The thirame group rats had the smallest body weight and the lowest food intake. All the pesticides-exposed animals has a higher liver weight than predicted by their body weight. The pesticides-containing diets decreased liver lactate concentration and the lac/pyr ratio. Thirame was the more efficient and it partly impaired the glucose induced increase of the cytoplasmic redox potential, as estimated from the variation of the lac/pyr ratio. The pesticide-containing diets also lowered the liver concentrations of beta-hydroxybutyrate, acetoacetate, and their ratio. Last the pesticides, which but slightly modified the liver contents in adenine nucleotides and inorganic phosphate in the fasting state, increased the ATP fall following cold exposure and decreased the net ATP synthesis produced by glucose administration. The thirame diet was the more efficient in our experimental conditions, the zinebe diet the least one. It was concluded in our discussion that dietary dithiocarbamates either induced a hyperthyroidic status in the animal, or acted themselves as thyroxin-like compounds, because the liver metabolism was more directed towards heat production than towards that of chemical energy available for syntheses.
La separation des populations cellulaires par sedimentation a ete mise au point a partir de suspensions heterogenes de cellules branchiales d'anguilles adaptees a l'eau de mer. Les vitesses de sedimentation varient principalement en fonction de la taille. Cette methode a permis d'obtenir des populations homogenes de cellules a chlorures (97% en volume) et de cellules respiratoires (95%). La viabilite des cellules verifiee par le test de coloration au bleu trypan est satisfaisante (85-95%). Les activites adenosinetriphosphatases anion ou cation dependantes ont ete mesurees et comparees sur les homogenats des differents types cellulaires. Des preparations de membranes plasmatiques de l'epithelium branchial d'anguilles (anguilla anguilla) adaptees en eau douce ont ete utilisees pour etudier les activites atpasiques insensibles a l'ouabaine, calcium et magnesium dependantes. Le calcium induit l-hydrolyse de l'atp: deux cinetiques ont ete observees en presence (ou en absence) de chelateurs, l'une avec un site de haute affinite (0,37 micromolaire ca2+), l'autre avec un site de faible affinite (10-20 micromolaire). Le site de haute affinite necessite du magnesium (mg2+ endogene suffit), mais est inhibe par l'apport de magnesium exogene. Le site de faible affinite ou enzyme semble avoir des parametres cinetiques comparables a ceux trouves pour l'hydrolyse de l'atp par le magnesium. Sans chelateurs les deux sites semblent stimules. Une stimulation des activites atpasiques de haute ou faible affinite au calcium ou magnesium dependantes a ete mise en evidence dans les membranes des cellules branchiales en relation avec une diminution de la concentration du calcium des milieux d'adaptation. Les resultats sont discutes en rapport avec les transports ioniques branchiaux
Branchial activities of Na + ,K + -ATPase (ouabain sensitive), Mg 2 + ATPase (ouabain insensitive) and kinetic analysis of high and low affinity Ca 2+ ATPase were measured in Anguilla anguilla that had been acclimated to demineralized water (DW, Ca < 10 ltM), freshwater (FW, Ca = 2 mM), and Low calcium freshwater (L-Ca, Ca = 0.9 mM). Na+,K+-ATPase activity decreased while ouabain insensitive activity increased when ambient Ca 2 + decreased. Two kinetic forms of Ca 2+ ATPase could be resolved in each environmental condition. The stimulation coefficients of both sites or enzymes were not affected by ambient Ca 2+ concentrations. The maximal velocity of both the high and the low affinity Ca2 + ATPase was increased when external Ca 2 + was decreased during acclimation. The low affinity Ca 2 + ATPase and the Mg 2+ stimulated enzyme could be a non specific enzyme accepting either Ca 2 + or Mg 2 +. Results are compared with previous results in the literature and in relation to the branchial morphology and ionic exchanges in fish.
Young Wistar male rats (120-130 g) were fasted overnight and given either 3 g ethanol/kg body weight, 1.5 g/kg arginine, 1.14 g/kg ornithine, or the association of ethanol and arginine, or ethanol and ornithine by the i.p. method. The animals were killed at 0 (controls), 20, 40, and 60 min after the injection. The time course of 13 compounds was followed in their liver. After arginine or ornithine administration, glutamate, aspartate, alanine, malate, citrate, and urea increased, while the ketone bodies, β-hydroxybutyrate, and acetoacetate decreased. The concentrations of a-oxoglutarate, pyruvate, and oxaloacetate did not change. The changes produced by ethanol were those presented in previous papers, but there were interactions when ethanol was given together with arginine or ornithine: they chiefly concerned alanine, citrate, and acetoacetate in the ornithine experiment, aspartate, glutamate, glutamine, and urea in the arginine one. Discussion of the results shows that arginine or ornithine promote a strong influx of metabolites from glutamate to malate, aspartate, and alanine. This probably decreases citrate synthesis from ethanol and overcomes ethanol effects at the a-oxoglutarate level. Ornithine was less efficient than arginine. Perhaps this is related to differences in urea and ammonia concentration changes in the two experiments.
