Lucien Barthelemy

Cardiovascular and ventilatory effects of catecholamines in unrestrained eels (Anguilla anguilla L.)

SummaryThe cardiovascular and ventilatory effects caused by exogenous catecholamines were completely different in winter and in summer. In winter, adrenaline and noradrenaline produced hypoventilation, bradycardia and a rise in arterial pressure whilst isoprenaline was without effect. Treatment with phentolamine showed that these cardiovascular and ventilatory effects resulted from the stimulation of α adrenoceptors only.In contrast it was demonstrated that the hyperventilatory and tachycardiac effects observed in summer were the consequence of stimulation of β adrenoceptors. After treatment with a β blocking agent, isoprenaline did not produce any significant effect whilst adrenaline and noradrenaline caused hypoventilation and bradycardia as in winter, but to a lesser extent; these responses were abolished by an α blocking agent.Several possible interpretations of these results are proposed in order to explain the different modes of action by which catecholamines produce the cardiovascular and ventilatory responses observed in winter on one hand and in summer on the other.

Laboratory system enabling long-term exposure (⩾ 30 d) to hydrostatic pressure (⩽ 101 atm) of fishes or other animals breathing water

A high-pressure water-circulation system is described which enables fish (or other animals breathing water) to be maintained at pressures up to 101 atm for at least one month. A typical experiment, measuring the oxygen consumption of the eelAnguilla anguilla over a period of 31 d, revealed a metabolic acclimation to pressure in this fish. This system has numerous advantages; e.g. it is possible to reproduce in situ environmental conditions at depth, thus enabling the study of the problems of pressure adaptation, and also to simulate vertical migrations of animals, allowing the study of associated physiological phenomenon.

A comparative study of oxygen toxicity in vertebrates

Survival time in conditions of hyperbaric oxygenation were measured in trout and eels in water, and in frog in water or in gas phase at various temperatures. In eel and trout, the gill surface is altered within 90 min at 15 ata pressure of oxygen. Survival times of the frog during hyperoxia in aquatic or gaseous conditions are only slightly different, in spite of the marked difference in the oxygen concentration of the two media. Oxygen toxicity is well correlated with the aerobic metabolic rate, (1) in a given species adapted to various temperatures; (2) in trout eel and frog observed at the same temperature. The differing O2 toxicities in homeothermic and poikilothermic animals are also related to the differences in metabolic activity.

Hydrostatic pressure induces a state resembling histotoxic hypoxia in Anguilla anguilla

Abstract 1. 1. Energy metabolism (substrates, enzyme activities) was studied in white muscle and liver of yellow freshwater eels ( Anguilla anguilla L.) exposed for 3 hr to 100 atm hydrostatic pressure in normoxic conditions and at constant water temperature. 2. 2. In the two tissues explored, a decrease occurred in glycogen content (the anaerobic substrate) and an accumulation of total fatty acids (exclusive aerobic substrate). Concomitant changes in substrate contents, decreased of cytochrome c oxidase activity and increased lactate dehydrogenase activity were observed. 3. 3. When complemented with observations (ATP, oxygen consumption) from previous studies, results were in agreement with an alteration of aerobic energy production and an activation of the anaerobic pathway. In fish, hydrostatic pressure appeared to induce a state resembling histotoxic hypoxia.

Effects of hydrostatic pressure per se (101 ATA) on energetic processes in fish.

Nucleotides concentrations (ATP, ADP, AMP) have been measured in brain and muscle of eels exposed to 101 ATA of hydrostatic pressure (HP) for 3 hr. Survival times (ST) and oxygen arterial content (CaO2) have been measured in trouts exposed to HP = 101 ATA. The results show that at HP = 101 ATA, AMP increases (P less than 0.05) and ATP decreases (-12%; NS) in muscle but are not modified in brain; ST values are similar in normoxic and hyperoxic conditions, and CaO2 are similar at 1 ATA and 101 ATA of HP. It is concluded that HP tends to decrease aerobic production of energy. This phenomenon is not due to a failure in O2 transport from ambient medium to the cell but to a possible perturbation of the aerobic cellular processes leading to energy production (Krebs cycle and/or respiratory chain coupled to oxidative phosphorylation.

Catecholamine content (as measured by the HPLC method) in brain and blood plasma of the eel: effects of 101 ata hydrostatic pressure☆

The catecholamine content (noradrenaline, NA; adrenaline, A; dopamine, DA, and its metabolite, DOPAC) was measured, by the HPLC method, in brain and blood plasma of eels studied at atmospheric pressure (1 ATA) or at 101 ATA of hydrostatic pressure (HP). In the brain, HP induces a slight but significant increase (P less than 0.05) in A and DA contents but NA and DOPAC levels are not modified at 101 ATA when compared to 1 ATA. In the plasma, only A and NA are detected, adrenaline being the predominant amine. In eels exposed to 101 ATA HP, A and NA are strongly increased (+100%; P less than 0.01). The significance of the catecholamine increase in brain and plasma of the eels under HP is discussed.

Effects of 5-HT serotonin on spontaneous locomotor activity of eels.

The swimming activity of eels maintained in tap water at 8-12 degrees C is significantly decreased after i.p. para-chlorophenylalanine (pCPA) administration at dose of 200 mg/kg (p less than 0.005 to respective control value). 5-Hydroxytryptophan (5-HTP) restored transitory swimming activity of eels. These results suggest that 5-HT has an important part in locomotor activity of eels.

Effects of long-term exposure to 101 ATA hydrostatic pressure on blood, gill and muscle composition and on some enzyme activities of the FW eel (Anguilla anguilla L.)

Abstract 1. 1. The study was set up to investigate the effects of long-term exposure (30 days) at 101 ATA of hydrostatic pressure (HP), in normoxic conditions and at constant temperature, on enzyme activities involved in energy production and ionic transfers. 2. 2. Measurements of activities of LDH, PFK, IDH and CPK in liver, red and white muscle seem to show that HP induces an improvement of aerobic pathway in red muscle and anaerobic pathway in white muscle; in liver no significant change is observed. 3. 3. At the same time, there appears an increase of plasma Na + , Cl − and Mg 2+ contents; in muscle and gill, only Na + and Cl − increase under pressure. Concomitantly with the changes in ion contents, there is a decrease in maximum activity of gill (Na + + K + )ATPase and Mg 2+ ATPase activity. 4. 4. The results agree with a Na + balance impairment occurring at the tissue level at the same time when a new state of energetic metabolism results from adjustments of intertissue coupling of anaerobic and aerobic metabolisms induced by a long-term exposure to hydrostatic pressure.

Brain and plasma biogenic amines analysis by the ec-PLC technique: application to fish

A HPLC technique has been developed for the analysis of biogenic amines (noradrenaline, NA; dopamine, DA; adrenaline, A; serotonin, 5-HT) in tissues and blood and then applied to fish. It appears that when compared to classical methods, HPLC is more rapid and reliable with a lower variation in the results. This technique showed that in eel blood, 5-HT and DA (and their metabolites) are missing or at least are present at very low concentrations.

Oxygen toxicity in trout at two seasons

Abstract 1. 1. Oxygen toxicity has been studied in trout. Survival times (ST) of fishes exposed at 1, 2, 3, 4 and 5 ATA of O2 partial pressure in water (PwO2) have been measured and related to metabolic rate. This study was conducted in winter (Tw = 14°C) and in summer (Tw = 19°C). 2. 2. There is no significant seasonal difference in O2 toxicity (estimated by ST) despite the increase in metabolic rate during summer. 3. 3. The results, which seem to be inconsistent with the classical theory of an O2 toxicity linked to the metabolic rate, are discussed as a possible consequence of the seasonal change in catecholaminergic reactivity and more generally, as the result of biochemical and physiological adaptations to the changes of the environmental conditions.