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Utilize este identificador para citar ou criar um link para este item: http://acervodigital.unesp.br/handle/11449/4205
Título: 
Cardiovascular changes under normoxic and hypoxic conditions in the air-breathing teleost Synbranchus marmoratus: importance of the venous system
Autor(es): 
Instituição: 
  • Aarhus University (AU)
  • Universidade Estadual Paulista (UNESP)
  • University of Birmingham
  • Universidade Federal de São Carlos (UFSCar)
ISSN: 
0022-0949
Resumo: 
Synbranchus marmoratus is a facultative air-breathing fish, which uses its buccal cavity as well as its gills for air-breathing. S. marmoratus shows a very pronounced tachycardia when it surfaces to air-breathe. An elevation of heart rate decreases cardiac filling time and therefore may cause a decline in stroke volume (VS), but this can be compensated for by an increase in venous tone to maintain stroke volume. Thus, the study on S. marmoratus was undertaken to investigate how stroke volume and venous function are affected during air-breathing. To this end we measured cardiac output (Q), heart rate (fH), central venous blood pressure (PCV), mean circulatory filling pressure (MCFP), and dorsal aortic blood pressures (PDA) in S. marmoratus. Measurements were performed in aerated water (P-O2 > 130 mmHg), when the fish alternated between gill ventilation and prolonged periods of apnoeas, as well as during hypoxia (P-O2 <= 50 mmHg), when the fish changed from gill ventilation to air-breathing. Q increased significantly during gill ventilation compared to apnoea in aerated water through a significant increase in both fH and VS. PCV and MCFP also increased significantly. During hypoxia, when the animals surface to ventilate air, we found a marked rise in fH, PCV, MCFP, Q and VS, whereas PDA decreased significantly. Simultaneous increases in PCV and MCFP in aerated, as well as in hypoxic water, suggests that the venous system plays an important regulatory role for cardiac filling and VS in this species. In addition, we investigated adrenergic regulation of the venous system through bolus infusions of adrenergic agonists (adrenaline, phenylephrine and isoproterenol; 2 mu g kg(-1)). Adrenaline and phenylephrine caused a marked rise in PCV and MCFP, whereas isoproterenol led to a marked decrease in PCV, and tended to decrease MCFP. Thus, it is evident that stimulation of both alpha- and beta-adrenoreceptors affects venous tone in S. marmoratus.
Data de publicação: 
15-Out-2006
Citação: 
Journal of Experimental Biology. Cambridge: Company of Biologists Ltd, v. 209, n. 20, p. 4167-4173, 2006.
Duração: 
4167-4173
Publicador: 
Company of Biologists Ltd
Palavras-chaves: 
  • adrenergic regulation
  • air-breathing fish
  • cardiac filling
  • mean circulatory filling pressure
  • normoxia
  • hypoxia
  • venous return
  • venous tone
  • stroke volume
  • Synbranchus marmoratus
Fonte: 
http://dx.doi.org/10.1242/jeb.02459
Endereço permanente: 
Direitos de acesso: 
Acesso restrito
Tipo: 
outro
Fonte completa:
http://repositorio.unesp.br/handle/11449/4205
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