Mechanisms of cardiac collapse at high temperature in a marine teleost (Girella nigrians)

Schwieterman, Gail D.; Hardison, Emily A.; Cox, Georgina K.; Van Wert, Jacey C.; Birnie-Gauvin, Kim; Eliason, Erika J.

doi:10.1016/j.cbpa.2023.111512

Cited by 2 publications

(1 citation statement)

References 75 publications

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“…Since the OCLTT hypothesis has not yet been shown universally to determine the upper temperature tolerance limits of fish, it is possible that alternative mechanisms could be involved, including disruption of neural function ( Ern et al., 2015 ; Jutfelt et al., 2019 ; Andreassen et al., 2022 ), impairment of cell membranes ( Bowler, 2018 ), enzyme denaturation ( Somero and Dahlhoff, 2008 ), ion imbalances (particularly of potassium) ( O’Sullivan et al., 2017 ; Zimmer et al., 2024 ) and failure of critical organs (e.g. heart or brain) ( Sidhu et al., 2014 ; Jørgensen et al., 2017 ; Andreassen et al., 2022 ; Schwieterman et al., 2023 ). Indeed, all of the above processes could be involved in determining the acute temperature tolerance of fish ( Ern et al., 2023 ), demonstrating the complexity of predicting how environmental changes may impact thermal limits.…”

Section: Introductionmentioning

confidence: 99%

Respiratory acidosis and O2 supply capacity do not affect the acute temperature tolerance of rainbow trout (Oncorhynchus mykiss)

Montgomery,

Finlay,

Simpson

et al. 2024

Conservation Physiology

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The mechanisms that determine the temperature tolerances of fish are poorly understood, creating barriers to disentangle how additional environmental challenges—such as CO2-induced aquatic acidification and fluctuating oxygen availability—may exacerbate vulnerability to a warming climate and extreme heat events. Here, we explored whether two acute exposures (~0.5 hours or ~72 hours) to increased CO2 impact acute temperature tolerance limits in a freshwater fish, rainbow trout (Oncorhynchus mykiss). We separated the potential effects of acute high CO2 exposure on critical thermal maximum (CTmax), caused via either respiratory acidosis (reduced internal pH) or O2 supply capacity (aerobic scope), by exposing rainbow trout to ~1 kPa CO2 (~1% or 10 000 μatm) in combination with normoxia or hyperoxia (~21 or 42 kPa O2, respectively). In normoxia, acute exposure to high CO2 caused a large acidosis in trout (blood pH decreased by 0.43 units), while a combination of hyperoxia and ~1 kPa CO2 increased the aerobic scope of trout by 28%. Despite large changes in blood pH and aerobic scope between treatments, we observed no impacts on the CTmax of trout. Our results suggest that the mechanisms that determine the maximum temperature tolerance of trout are independent of blood acid–base balance or the capacity to deliver O2 to tissues.

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Section: Introductionmentioning

confidence: 99%

Respiratory acidosis and O2 supply capacity do not affect the acute temperature tolerance of rainbow trout (Oncorhynchus mykiss)

Montgomery,

Finlay,

Simpson

et al. 2024

Conservation Physiology

View full text Add to dashboard Cite

show abstract

Measuring maximum heart rate to study cardiac thermal performance and heat tolerance in fishes

Gilbert,

Hardison,

Farrell

et al. 2024

Journal of Experimental Biology

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The thermal sensitivity of heart rate (fH) in fishes has fascinated comparative physiologists for well over a century. We now know that elevating fH is the primary mechanism through which fishes increase convective oxygen delivery during warming to meet the concomitant rise in tissue oxygen consumption. Thus, limits on fH can constrain whole-animal aerobic metabolism. In this Review, we discuss an increasingly popular methodology to study these limits, the measurement of pharmacologically induced maximum fH (fH,max) during acute warming of an anaesthetized fish. During acute warming, fH,max increases exponentially over moderate temperatures (Q10∼2–3), but this response is blunted with further warming (Q10∼1–2), with fH,max ultimately reaching a peak (Q10≤1) and the heartbeat becoming arrhythmic. Because the temperatures at which these transitions occur commonly align with whole-animal optimum and critical temperatures (e.g. aerobic scope and the critical thermal maximum), they can be valuable indicators of thermal performance. The method can be performed simultaneously on multiple individuals over a few hours and across a broad size range (<1 to >6000 g) with compact equipment. This simplicity and high throughput make it tractable in lab and field settings and enable large experimental designs that would otherwise be impractical. As with all reductionist approaches, the method does have limitations. Namely, it requires anaesthesia and pharmacological removal of extrinsic cardiac regulation. Nonetheless, the method has proven particularly effective in the study of patterns and limits of thermal plasticity and holds promise for helping to predict and mitigate outcomes of environmental change.

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Mechanisms of cardiac collapse at high temperature in a marine teleost (Girella nigrians)

Cited by 2 publications

References 75 publications

Respiratory acidosis and O2 supply capacity do not affect the acute temperature tolerance of rainbow trout (Oncorhynchus mykiss)

Respiratory acidosis and O2 supply capacity do not affect the acute temperature tolerance of rainbow trout (Oncorhynchus mykiss)

Measuring maximum heart rate to study cardiac thermal performance and heat tolerance in fishes

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