Effects of hibernation on mitochondrial regulation and metabolic capacities in myocardium of painted turtle (Chrysemys picta)

Birkedal, Rikke; Gesser, H.

doi:10.1016/j.cbpb.2004.09.023

Cited by 19 publications

(18 citation statements)

References 17 publications

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“…Anoxic exposure had a dramatic effect on heart metabolism, with a 20-fold increase in [ The effect of anoxia on cardiac fibre respiration Fibres were in good condition throughout the protocol, as shown by the minimal effect of cytochrome c injection on the percentage change in respiration rate (normoxia exposed, 2.58±1.10%; anoxia exposed, 0.72±0.42%; no significant difference between experimental groups). ACRs of permeabilised cardiac fibres from T. scripta ranged between 4 and 8 (Fig.1B), which is marginally higher than values previously reported for another species of freshwater turtle, C. picta (Birkedal and Gesser, 2004), which indicates that the fibres were in good condition. Two weeks of anoxia exposure led to a significant reduction in respiration rate in cardiac fibres supplied with substrates for Complex I (pyruvate + malate, State III respiration) and Complex IV (TMPD) (Fig.1B).…”

Section: Effect Of Chronic Anoxic Exposurecontrasting

confidence: 55%

“…Functional studies on the brain of T. scripta have shown that the activation of mitochondrial K ATP channels during anoxia limits Ca 2+ entry into the mitochondria and decreases N-methyl-D-aspartate receptor (NMDAR) activity (Pamenter et al, 2008). While many studies have identified anoxiainduced molecular and biochemical modifications to turtle mitochondria, mitochondrial respiration in Chrysemys picta appears to be unaffected by chronic anoxia exposure (Birkedal and Gesser, 2004); however, a detailed analysis of the components of mitochondrial respiration in T. scripta has not yet been performed.…”

Section: Introductionmentioning

confidence: 99%

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Beating oxygen: chronic anoxia exposure reduces mitochondrial F1FO-ATPase activity in turtle (Trachemys scripta) heart

Galli

Lau

Richards

2013

Journal of Experimental Biology

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SUMMARYThe freshwater turtle Trachemys scripta can survive in the complete absence of O 2 (anoxia) for periods lasting several months. In mammals, anoxia leads to mitochondrial dysfunction, which culminates in cellular necrosis and apoptosis. Despite the obvious clinical benefits of understanding anoxia tolerance, little is known about the effects of chronic oxygen deprivation on the function of turtle mitochondria. In this study, we compared mitochondrial function in hearts of T. scripta exposed to either normoxia or 2weeks of complete anoxia at 5°C and during simulated acute anoxia/reoxygenation. Mitochondrial respiration, electron transport chain activities, enzyme activities, proton conductance and membrane potential were measured in permeabilised cardiac fibres and isolated mitochondria. Two weeks of anoxia exposure at 5°C resulted in an increase in lactate, and decreases in ATP, glycogen, pH and phosphocreatine in the heart. Mitochondrial proton conductance and membrane potential were similar between experimental groups, while aerobic capacity was dramatically reduced. The reduced aerobic capacity was the result of a severe downregulation of the F 1 F O -ATPase (Complex V), which we assessed as a decrease in enzyme activity. Furthermore, in stark contrast to mammalian paradigms, isolated turtle heart mitochondria endured 20min of anoxia followed by reoxygenation without any impact on subsequent ADP-stimulated O 2 consumption (State III respiration) or State IV respiration. Results from this study demonstrate that turtle mitochondria remodel in response to chronic anoxia exposure and a reduction in Complex V activity is a fundamental component of mitochondrial and cellular anoxia survival.

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Section: Effect Of Chronic Anoxic Exposurecontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Beating oxygen: chronic anoxia exposure reduces mitochondrial F1FO-ATPase activity in turtle (Trachemys scripta) heart

Galli

Lau

Richards

2013

Journal of Experimental Biology

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“…Freshwater turtles as a group, as described in a classic study by Smith (29), have unusually high HCO 3 Ϫ concentrations in plasma and other extracellular fluids compared with other vertebrates, but within the group of turtles we studied, significant differences in HCO 3 Ϫ concentrations have been observed. Based on measured values from the submergence studies that provide the background for the present study, the more anoxiatolerant species have higher plasma HCO 3 Ϫ concentrations than the less anoxia-tolerant species (Table 2).…”

Section: Discussionmentioning

confidence: 67%

“…Another factor contributing to differences in buffering capacity among turtles that also may contribute to observed differences in shell carbonate among turtles and between turtles and other vertebrates is plasma HCO 3 Ϫ concentration. Freshwater turtles as a group, as described in a classic study by Smith (29), have unusually high HCO 3 Ϫ concentrations in plasma and other extracellular fluids compared with other vertebrates, but within the group of turtles we studied, significant differences in HCO 3 Ϫ concentrations have been observed.…”

Section: Discussionmentioning

confidence: 99%

Comparative shell buffering properties correlate with anoxia tolerance in freshwater turtles

Jackson¹,

Taylor²,

Asare³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…This finding appears odd as numerous examples exist of ectotherms altering enzyme activity, cardiovascular function and metabolism in direct response to chronic changes in environmental temperature (Zari 1999;Hicks & Farrell 2000;Birkedal & Gesser 2004;Seebacher 2005;Seebacher et al 2009), and crocodilians show significant changes in the activities of regulatory metabolic enzymes after only a few weeks of thermal acclimatization (Glanville & Seebacher 2006;Seebacher et al 2009). Most field studies on the thermal biology of reptiles have however focused on their acclimatization to cold temperatures, and ectotherms from temperate regions that use hypometabolic strategies are often the study species.…”

Section: Discussionmentioning

confidence: 99%

Diving through the thermal window: implications for a warming world

et al. 2010

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Population decline and a shift in the geographical distribution of some ectothermic animals have been attributed to climatic warming. Here, we show that rises in water temperature of a few degrees, while within the thermal window for locomotor performance, may be detrimental to diving behaviour in airbreathing ectotherms (turtles, crocodilians, marine iguanas, amphibians, snakes and lizards). Submergence times and internal and external body temperature were remotely recorded from freshwater crocodiles (Crocodylus johnstoni) while they free-ranged throughout their natural habitat in summer and winter. During summer, the crocodiles' mean body temperature was 5.2 + 0.18C higher than in winter and the largest proportion of total dive time was composed of dive durations approximately 15 min less than in winter. Diving beyond 40 min during summer required the crocodiles to exponentially increase the time they spent on the surface after the dive, presumably to clear anaerobic debt. The relationship was not as significant in winter, even though a greater proportion of dives were of a longer duration, suggesting that diving lactate threshold (DLT) was reduced in summer compared with winter. Additional evidence for a reduced DLT in summer was derived from the stronger influence body mass exerted upon dive duration, compared to winter. The results demonstrate that the higher summer body temperature increased oxygen demand during the dive, implying that thermal acclimatization of the diving metabolic rate was inadequate. If the study findings are common among air-breathing diving ectotherms, then long-term warming of the aquatic environment may be detrimental to behavioural function and survivorship.

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Effects of hibernation on mitochondrial regulation and metabolic capacities in myocardium of painted turtle (Chrysemys picta)

Cited by 19 publications

References 17 publications

Beating oxygen: chronic anoxia exposure reduces mitochondrial F1FO-ATPase activity in turtle (Trachemys scripta) heart

Beating oxygen: chronic anoxia exposure reduces mitochondrial F1FO-ATPase activity in turtle (Trachemys scripta) heart

Comparative shell buffering properties correlate with anoxia tolerance in freshwater turtles

Diving through the thermal window: implications for a warming world

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