Data/hora: 06/06/2024 06:21:38

Provedor de dados: | 5
País: | France
Título: | Modulation des performances cardio-respiratoires du bar europeen (Dicentrarchus labrax) par l'apport d'acides gras alimentaires: une etude integree des effets cardiaques in vivo au courant calcique de type L des myocytes ventriculaires
Autores: | Chatelier, Aurelien.
Data: | 2005-12
Ano: | 2005
Palavras-chave: | Dicentrarchus labrax; Arythmie cardiaque; Hypoxie; Acide oléique; Canal calcique de type L; Calcium; Nage; Métabolisme; Coeur; Acides gras; Dicentrarchus labrax; Cardiac arrhythmias; Hypoxia; Oleic acid; L type calcium channel; Calcium; Metabolism; Heart; Fatty acid.
Resumo: | Diet quality, and particularly fatty acids composition, is an environmental factor that is emerging as a significant source of physiological diversity. Indeed, numerous recent studies show that the fatty acid composition of the diet influences cardiac and metabolic performances of organisms. Because it is involved in the control and regulation of internal flow of matter and energy, the heart is believed to play a central role in environmental adaptation in fish. Within the double context of adaptation of individuals to their ecological niche and species evolution, understanding sources of interindividual variability and particularly fatty acid influences on the cardiorespiratory system is essential.  The objective of the study was to investigate in the sea bass (Dicentrarchus labrax) and at two organisational levels, the effects of fatty acids on: - cardio-respiratory performance during a force swim test and a hypoxic test - L-type calcium channel activity of ventricular myocytes.  Sea bass were fed with three different diets enriched with fish oil (rich in n-3 polyunsaturated fatty acid), canola oil (rich in oleic acid and linoleic acid) or palm oil (rich in saturated fatty acid).  The study carried out at the whole animal scale was performed using a Brett respirometer. This study shows that dietary fatty acid composition significantly affects sea bass cardio-respiratory performances. Oleic acid content in the diet but also in the cardiac tissue is associated with improved cardiac and metabolic performance. The hypoxic test revealed no significant difference between experimental diets.  Electrophysiological studies on L-type calcium channel were performed using the whole-cell configuration of the patch-clamp technique. Our results reveal that both oleic acid perfusion and high membrane content of oleic acid induce a reduction in calcium influx through the sarcolemma via L-type calcium current conductance. This decrease is not accompanied change in activation and inactivation parameters of the current.  Owing to its morpho-functional characteristics, the heart is believed to be the weak link of metabolic and swimming performance in fishes. During an intensive muscular challenge, the decrease in oxygen venous blood (the main source of oxygen for the myocardial tissue) leads to cardiomyocytes hypoxia. Cardiac hypoxia are associated with perturbations of intra-cellular calcium homeostasis with cell calcium overload and arrhythmias. Experimental results suggest that oleic acid, by inhibiting L type calcium current, limit cardiac arrhythmia occurrence. This protective effect of oleic acid could be responsible for the observed improved cardio-respiratory and swimming performance in animals fed with the diet enriched with canola oil.
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/2005/these-2197.pdf
Editor: | Université de la Rochelle
Relação: | http://archimer.ifremer.fr/doc/00000/2197/
Formato: | application/pdf