Life Lines by Dr. Dolittle

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Tag Archive for ‘hypoxia’

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High altitude survival and adaptation

Life at high altitude presents unique physiological challenges for organisms that were explored in a recent review published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. For placental mammals, offspring born at high altitude (>2500 m above sea level) typically weigh less at birth compared to lowland animals. Fetal growth restriction is problematic as it is associated with long-term health risks and reduced survival. It is […]

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Extreme Physiology of Diving

Can you imagine what would happen to your body if you dove up to 1700 meters deep in the ocean for an hour and a half, or experienced months of food deprivation? In the case of deep diving, the high pressure causes the collapse of the lungs of terrestrial mammals (including humans!) and depletion of body oxygen stores, whereas long fasting periods compromise health and induce muscle wasting. Northern elephant […]

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Surviving the cold

The ability to regulate body temperature is critical for animals. This is especially true for small mammals as they have a larger surface area resulting in more heat loss to the environment than larger animals. Animals that stay active during the winter likewise have to spend more energy to stay warm. To do this well, they need to balance heat loss with heat generation through shivering as well as non-shivering […]

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Anoxia tolerance in goldfish

The reason mammals are not very good at tolerating hypoxic (i.e. low oxygen) environments, is because the brain relies heavily on oxygen for metabolism. It is so stingy, it uses about 20% of the oxygen in the body to make ATP. Without oxygen, the brain has to rely on glycolysis to make ATP and this process is not good at meeting the energy requirements of the neurons, ultimately resulting in […]

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Nature’s architects

Nature has already solved many problems that doctors, researchers, and architects are still trying to solve for humans. For example, some of our prior posts have talked about how some animals are resistant to developing cancer: Elephants Tasmanian devils Naked mole rats Other animals have developed special nano antibodies (nanobodies) to fight disease. Llamas While several are tolerant of very low oxygen levels in the environment, others are champions of […]

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Hypoxia improves exercise duration

Speaking of hypoxia, a new study published in Physiological Reports examined how training for 2 weeks under 18% hypoxia impacts muscles of Thoroughbred horses. Unlike humans, these horses do not increase production of red blood cells to enhance oxygen transport throughout the body under hypoxic conditions. This difference led researchers to speculate that the horses had other ways of adapting to exercise.   In the new study, horses were trained […]

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Cholesterol levels in tissues change during hypoxia in naked mole rats

Naked mole rats are rather famous from a physiological perspective for their amazing ability to live in hypoxic conditions. They do so in part by reducing their metabolic rate. In fact, researchers at the University of Ottawa in Canada showed that reducing environmental oxygen levels to 11% resulted in a 34% decrease in the animal’s metabolic rate. Studies of hypoxia-tolerant goldfish show that the animals respond to hypoxia challenges by […]

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Physiology of diving animals: how do they deal with hypoxia?

Dr. Jose Pablo Vazquez-Medina (pictured at right), a comparative physiologist at the University of California – Berkeley, was scheduled to present several ongoing studies from his lab at the Experimental Biology conference last month. Dr. Vazquez-Medina is a member of the Comparative and Evolutionary Physiology section of the American Physiological Society. Although the conference was cancelled due to Covid-19, Dr. Vazquez-Medina has agreed to share his research with us.   […]

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How some fish may compensate for low environmental oxygen

     Adult fish rely on gills to extract oxygen from the surrounding water. Larval fish, on the other hand, do not have well-developed gills and instead rely primarily on gas exchange across their skin.      In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers examined whether larval fish could use their pectoral fins to increase the flow of water […]

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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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