Respirometer
{{Short description|Device for measuring the rate of respiration}}
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A respirometer is a device used to measure the rate of respiration{{cite book |last1=Toole |first1=Glenn |last2=Toole |first2=Sue |title=Essential A2 Biology for OCR |date=2004 |publisher=Nelson Thornes |isbn=9780748785186 |page=18 |url=https://books.google.com/books?id=_X3JMl3Eo-4C&q=respirometer&pg=PA18 |access-date=23 August 2018 |language=en}} of a living organism by measuring its rate of exchange of oxygen and/or carbon dioxide.{{Cite web|url=http://www.phschool.com/science/biology_place/labbench/lab5/respwork.html|title=Pearson - The Biology Place|website=www.phschool.com|access-date=2019-10-29}} They allow investigation into how factors such as age, or chemicals affect the rate of respiration.{{Cite web|url=https://www.nuffieldfoundation.org/practical-biology/measuring-rate-metabolism|title=Measuring the rate of metabolism {{!}} Nuffield Foundation|website=www.nuffieldfoundation.org|access-date=2019-10-29}} Respirometers are designed to measure respiration either on the level of a whole animal or plant or on the cellular level. These fields are covered by whole animal and cellular (or mitochondrial) respirometry, respectively.{{Cite journal|last1=Beeson|first1=Craig C.|last2=Beeson|first2=Gyda C.|last3=Schnellmann|first3=Rick G.|date=2010-09-01|title=A high-throughput respirometric assay for mitochondrial biogenesis and toxicity|journal=Analytical Biochemistry|volume=404|issue=1|pages=75–81|doi=10.1016/j.ab.2010.04.040|issn=1096-0309|pmc=2900494|pmid=20465991}}
A simple whole plant respirometer designed to measure oxygen uptake or CO2 release consists of a sealed container with the living specimen together with a substance to absorb the carbon dioxide given off during respiration, such as soda lime pellets or cotton wads soaked with potassium hydroxide. The oxygen uptake is detected by manometry.{{Cite web|url=https://www.nuffieldfoundation.org/practical-biology/measuring-respiratory-quotient|title=Measuring respiratory quotient {{!}} Nuffield Foundation|website=www.nuffieldfoundation.org|access-date=2019-10-29}} Typically, a U-tube manometer is used, which directly shows the pressure difference between the container and the atmosphere. As an organism takes up O2, it generates a proportionate quantity of CO2 (see respiratory quotient), but all the CO2 is absorbed by the soda lime. Therefore, all of the drop of pressure in the chamber can be attributed to the drop of O2 partial pressure in the container. The rate of change gives a direct and reasonably accurate reading for the organism's rate of respiration.
As changes in temperature or pressure can also affect the displacement of the manometric fluid, a second respirometer identical to the first except with a dead specimen (or something with the same mass as the specimen in place of the organism) is sometimes set up. Subtracting the displacement of the second respirometer from the first allows for control of these factors.
The set up of modern respirometers is described in more detail under respirometry. A respirometer may also be called an oxygraph.{{Cite journal|last1=Djafarzadeh|first1=Siamak|last2=Jakob|first2=Stephan M.|date=2017-02-08|title=High-resolution Respirometry to Assess Mitochondrial Function in Permeabilized and Intact Cells|url=https://www.jove.com/video/54985/high-resolution-respirometry-to-assess-mitochondrial-function|journal=Journal of Visualized Experiments|issue=120|pages=e54985|doi=10.3791/54985|pmid=28287504|pmc=5408571|issn=1940-087X}} Suppliers for whole animal respirometers are e.g. Sable Systems, Respirometer Systems and Applications, Qubit Systems, Eco-environment, Bio-technology, or Challenge Technology; for mitochondrial respirometers, Oroboros Instruments,{{Cite web|url=https://www.oroboros.at/index.php?id=high-resolution-respirometry|title=Oroboros: HRR|website=www.oroboros.at|access-date=2019-10-29}} Hansatech Instruments,{{Cite web|url=http://www.hansatech-instruments.com/product/chlorolab-3-system/|title=Chlorolab 3+ System|website=Hansatech Instruments Ltd|language=en-GB|access-date=2019-10-29}} or YSI.{{Cite web|url=https://www.ysi.com/ysi-blog/water-blogged-blog/2017/08/biosensor-technology-ysi-life-sciences|title=Biosensor Technology |date=August 29, 2017|first=Will |last=Miller |website=www.ysi.com|access-date=2019-10-29}}