Oxygen supply capacity breathes new life into critical oxygen partial pressure (Pcrit)
| Autor: | Alexandra L Burns, Matthew A. Birk, C Tracy Shaw, Christina J Welsh, Alexander W Timpe, Brad A. Seibel, Alyssa Andres |
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| Rok vydání: | 2021 |
| Předmět: |
0106 biological sciences
Ocean deoxygenation Physiology Partial Pressure 030310 physiology Thermodynamics chemistry.chemical_element Aquatic Science 010603 evolutionary biology 01 natural sciences Oxygen 03 medical and health sciences Respirometry Oxygen Consumption medicine Animals Hypoxia Molecular Biology Ecology Evolution Behavior and Systematics 0303 health sciences Oxygen supply Chemistry Temperature Partial pressure Hypoxia (medical) Insect Science Metabolic rate Animal Science and Zoology medicine.symptom Oxygen level |
| Zdroj: | Journal of Experimental Biology. 224 |
| ISSN: | 1477-9145 0022-0949 |
| DOI: | 10.1242/jeb.242210 |
| Popis: | The critical oxygen partial pressure (Pcrit), typically defined as the PO2 below which an animal's metabolic rate (MR) is unsustainable, is widely interpreted as a measure of hypoxia tolerance. Here, Pcrit is defined as the PO2 at which physiological oxygen supply (α0) reaches its maximum capacity (α; µmol O2 g−1 h−1 kPa−1). α is a species- and temperature-specific constant describing the oxygen dependency of the maximum metabolic rate (MMR=PO2×α) or, equivalently, the MR dependence of Pcrit (Pcrit=MR/α). We describe the α-method, in which the MR is monitored as oxygen declines and, for each measurement period, is divided by the corresponding PO2 to provide the concurrent oxygen supply (α0=MR/PO2). The highest α0 value (or, more conservatively, the mean of the three highest values) is designated as α. The same value of α is reached at Pcrit for any MR regardless of previous or subsequent metabolic activity. The MR need not be constant (regulated), standardized or exhibit a clear breakpoint at Pcrit for accurate determination of α. The α-method has several advantages over Pcrit determination and non-linear analyses, including: (1) less ambiguity and greater accuracy, (2) fewer constraints in respirometry methodology and analysis, and (3) greater predictive power and ecological and physiological insight. Across the species evaluated here, α values are correlated with MR, but not Pcrit. Rather than an index of hypoxia tolerance, Pcrit is a reflection of α, which evolves to support maximum energy demands and aerobic scope at the prevailing temperature and oxygen level. |
| Databáze: | OpenAIRE |
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