Life Lines by Dr. Dolittle

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Tag Archive for ‘American Journal of Physiology’

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Researchers explore why fetuses that experienced intrauterine growth restriction have smaller muscles

We have talked several times about the long-lasting issues related to growth restriction of a fetus during pregnancy: Intrauterine growth restriction increases risk of cardiovascular disease as adults Intrauterine growth restriction increases risk of insulin resistance as adults It can also result in offspring that have smaller muscles. New research published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology suggests this may be due to adaptations to […]

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Warm hypoxic waters impair heart function in some fish

Events causing bodies of water to become hypoxic (low oxygen levels) are increasing with climate change. Water can become hypoxic when it warms up or there are changes in tidal flow, density, wind patterns as well as separation from the main source, such as occurs in a tidepool. While some fish are tolerant of hypoxia and even anoxia (oxygen depleted) environments others, such as Atlantic cod and steelhead trout, rely […]

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Adults are better adapted to survive without oxygen

Adult fruit flies (Drosophila melanogaster) are more tolerant of environments devoid of oxygen than their larvae. In fact, they are able to survive up to 12 hours without oxygen by becoming paralyzed, which enables them to dramatically reduce metabolism and the need for oxygen. In contrast, Drosophila larvae expend a lot of energy trying to escape and are only able to tolerate a couple of hours without oxygen. This is surprising […]

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Remarkable hypoxia and cold tolerance of rodents native to the Tibetan plateau

The plateau zokor (Eospalax baileyi) is an underground dwelling rodent species native to the Tibetan plateau (2000-4200 meters in elevation). A new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology explored how these animals were adapted to extract oxygen from an environment with very low levels (83-88% of atmospheric). Hemoglobin molecules found in red blood cells are responsible for binding oxygen and transporting it to tissues […]

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High altitude deer mice have less stress?

Animals that live at high altitude have evolved a number of physiological adaptations to deal with the low atmospheric oxygen concentrations (hypoxia). For low altitude acclimated animals, short exposures to high altitude results in activation of the sympathetic nervous system (i.e. the fight or flight response). This is a good thing because activation of this system results in more blood flow, especially to the heart and brain to help protect oxygen […]

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Did you know just how interesting shark rectal glands could be?

In case you missed Shark Week this year, I thought I would mention a cool fact about dogfish sharks (Squalus acanthias) that you probably did not learn about. I read an interesting article from a lecture given by Dr. John N Forrest Jr, M.D. that was published in 2016 in Transactions of the American Clinical and Climatological Association. Sharks have a complicated system for regulating water and salt balance in the […]

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Rapid switches in metabolism of hibernating animals

  In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers examined how changes in metabolism during torpor are regulated in 13-lined ground squirrels (Ictidomys tridecemlineatus). During hibernation, these animals cycle between bouts of torpor (about 2 weeks each) when their metabolism is reduced by 95% and body temperature can drop to 5degC and short states of interbout euthermia when both temperature […]

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