Carbohydrate management, anaerobic metabolism, and adenosine levels in the armoured catfish,Liposarcus pardalis (castelnau), during hypoxia (original) (raw)
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2016
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Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2013
Carassius carassius responds to hypoxic conditions by conversion of lactate into ethanol, which is excreted over the gills. However, a closely related species, Cyprinus carpio, does not possess the ability to produce ethanol and would be expected to accumulate lactate during hypoxic exposure. While the increase in oxygen consumption in fish required following strenuous exercise or low environmental oxygen availability has been frequently considered, the primary contributing mechanism remains unknown. This study utilized the close relationship but strongly divergent physiology between C. carpio and C. carassius to examine the possible correlation between excess post-hypoxic oxygen consumption (EPHOC) and lactate accumulation. No difference in the EPHOC:O 2 deficit ratio was observed between the two species after 2.5 h anoxia, with ratios of 2.0 ± 0.6 (C. carpio) and 1.3 ± 0.3 (C. carassius). As predicted, lactate accumulation dynamics did significantly differ between the species in both plasma and white muscle following anoxic exposure. Significant lactate accumulation was seen in both plasma and muscle in C. carpio, but there was no accumulation of lactate in white muscle tissue of C. carassius. These findings indicate that lactate accumulated as a consequence of 2.5 h anoxic exposure is not a major determinant of the resulting EPHOC.
Canadian Journal of Zoology-revue Canadienne De Zoologie, 2003
Amazonian armoured catfishes exhibit substantial cardiac hypoxia tolerance, but little is known concerning organismal cardiorespiratory, metabolic, and behavioural responses to low oxygen levels. This study assessed the general mechanisms used by two species of armoured catfish, Glyptoperichthyes gibbceps and Liposarcus pardalis, to survive the frequent periods of hypoxia encountered in the Amazon River. The gill ventilation rate (f v ) and heart rate (f h ) were studied under controlled hypoxia in aquaria and under natural hypoxia in a simulated pond. Glyptoperichthyes gibbceps were fitted with radiotelemetry tags and held in field cages to study their habits of depth selection and air breathing. When denied aerial respiration under hypoxia in aquaria, G. gibbceps increased f v , but neither they nor L. pardalis exhibited alterations in f h . An increase in f v was initially observed in G. gibbceps during pond hypoxia before aerial respiration was initiated and f v declined. Glyptoperichthyes gibbceps were hyperglycaemic under normoxia, and extremely large increases in plasma glucose and lactate concentrations were observed under hypoxia. Field studies confirmed their nocturnal behaviour and showed that air breathing increased at night, regardless of dissolved oxygen concentration. Our results show that armoured catfishes preferentially up-regulate f v and anaerobic metabolism and exhibit no bradycardia during hypoxia.
Gut blood flow in fish during exercise and severe hypercapnia
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2001
This paper reviews the effects of exercise and hypercapnia on blood flow to the splanchnic circulation. Brief struggling Ž . behaviours are known to decrease blood flow to the gut GBF . Likewise, prolonged swimming in unfed fish has been shown to reduce GBF in proportion to the increased oxygen uptake. Therefore, the normal postprandial increase in GBF theoretically should be impaired whenever fish are active. However, indirect evidence suggests that GBF is spared Ž . to some degree when fed fish swim continuously but at a cost 10᎐15% to their critical swimming speed. Severe respiratory acidosis can be created by the new intensive aquaculture settings that use oxygen injection into re-circulated water. The only study so far to examine the effects of severe hypercapnia on GBF and its regulation showed that routine Ž . GBF and ␣-adrenergic control of GBF remained normal in unfed white sturgeon Acipenser transmontanus . However, severe hypercapnia produced a hyperactive state and increased sensitivity of GBF to struggling. As a result, routine GBF was maintained for a short period of time. Thus, environmental changes such as severe hypercapnia can indirectly impact GBF through altered struggling behaviour, but the implications of the overall reduction in GBF to food assimilation have yet to be established. ᮊ A.P. Farrell .
Eleni Mente, Alexia Legeay, Dominic F. Houlihan and Jean-Charles Massabuau
AJP Regulatory Integrative and Comparative Physiology
1 other HighWire hosted article: This article has been cited by [PDF] [Full Text] [Abstract] , January 1, 2005; 208 (1): 83-91. J. Exp. Biol. I. J. McGaw during hypoxia? Does feeding limit cardiovascular modulation in the Dungeness crab Cancer magister on the following topics: http://highwire.stanford.edu/lists/artbytopic.dtl can be found at Medline items on this article's topics Physiology .. Malacostraca Chemistry .. Peptide Bonds Oncology .. Rate of Protein Synthesis Oncology .. Protein Synthesis including high-resolution figures, can be found at: Updated information and services http://ajpregu.physiology.org/cgi/content/full/284/2/R500 can be found at: and Comparative Physiology American Journal of Physiology -Regulatory, Integrative about Additional material and information . Influence of oxygen partial pressures on protein synthesis in feeding crabs. Am J Physiol Regul Integr Comp Physiol 284: R500-R510, 2003; 10.1152/ ajpregu.00193.2002.
Summary of Findings and Recommendations
2000
This book responds to questions in three general areas: characterization of hypoxia; characterization of nutrient fate, transport and sources; and the scientific basis for goals and management options. In the sections below, these questions (shown in italics below) are addressed very briefly with references to those sections of this book where more detailed science on that particular question may be