Life Lines by Dr. Dolittle

Tag Archive for ‘American Journal of Physiology’

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Primed for survival: How sea hares inspire new clues to protect the brain from low oxygen conditions such as stroke

Sea hares (Aplysia californica) live in coastal environments where oxygen levels can fluctuate unpredictably. Knowing this, researchers set out to explore how these animals tolerate regular exposure to hypoxia (low oxygen) with the hope of discovering clues that could teach us how to protect humans from hypoxia-related conditions, such as stroke. To do this, they compared offspring from two types of parents: those collected from the wild that likely experienced […]

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Brown adipose tissue: not just a heater or fat-burning machine

Once dismissed as a feature only babies possess, brown adipose tissue (BAT), is widely recognized as the body’s metabolism-boosting, heat-generating fat. This Time Machine episode takes a look back at early research and new discoveries about this metabolism-boosting fat. According to a 2007 paper published in the American Journal of Physiology – Endocrinology and Metabolism, it was the ability for BAT to take up glucose that enabled its discovery in […]

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Time Machine: Do horses produce more heat per day than humans, and what happened to Tusko?

In this post, we travel back to 1947 to explore a fascinating review by Dr. Max Kleiber from the University of California – Davis. Published in Physiological Reviews, this review examined the relationship between body size and metabolism. Simply asking the question of whether horses produce more heat per day than humans or rats will lead one to conclude that indeed they do because of their larger body size. However, […]

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Time machine: The discovery of heparin

In this post, we take a step back in time to feature two legacy articles published in the American Journal of Physiology, written by Jay McClean and Dr. William Howell who studied the physiology of blood clotting. With the 2025 American Physiology Summit taking place in Baltimore, it is only fitting that we take a step back in time to celebrate their important discoveries. Dr. Howell was born in Baltimore, […]

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The Science Behind Human Endurance Capabilities

Among mammals, humans are known for having exceptional endurance. For example, persistence hunters can run for 2-5 hours to wear out their prey, while marathoners routinely run ~4.5 hours on average (Schulte et al., 2015). Sure, a cheetah can run fast, but it can’t run as long as a human. How did humans develop such exceptional endurance? When vertebrates moved to dry land, they needed to develop lungs to extract […]

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It’s all about the glucose

A lack of available food resources drives many species to forego reproduction until conditions improve. In other words, there is a trade-off between reproduction and foraging. This link was the subject of a recent study of Drosophila melanogaster published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology.   To examine the link, researchers placed fed or food-deprived Drosophila into a testing arena with another animal of […]

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New study provides more insight into the physiology of elite divers

If the Olympics allowed marine mammals to compete, they would dominate free diving competitions in terms of breath holding duration and extreme physiology. Marine mammals also have adaptations that help prevent tissue damage from the lack of oxygen during such dives. For example, Weddell and northern elephant seals store large amounts of oxygen in their blood and muscles, thanks to abundant hemoglobin, which permits them to hold their breath for […]

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Even shy animals find overcrowded conditions more stressful than bold animals

In a newly published study in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers examined the relationship between behavioral and physiological responses to stress in a model organism, zebrafish. Following a series of behavioral tests, the fish were classified as either shy or bold and were then exposed to either overcrowded (32 fish per liter) or control conditions (1.6 fish per liter). After 10 days, the […]

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Let’s stop lactate-shaming

As wisely stated in an editorial by Dr. George Brooks, UC Berkeley (2001), “Nature is smarter, and things are more complex than we mortals imagine.” Sure lactate is produced during exercise and is often blamed for causing muscles to fatigue, but there is much more to the story. In fact, research has shown that lactate plays many important physiological roles in the body such as serving as a metabolic fuel […]

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Roses are red, violets are blue, beluga whales and dolphins have higher carbon monoxide than you

The lifespan of a red blood cell (RBC) in a healthy human is about 120 days and approximately 200 billion red blood cells (RBCs) are replaced every day in healthy adult humans! Most (80%) of the carbon monoxide produced in humans comes from the breakdown of heme which is released when these red blood cells (RBC) are broken down through normal homeostatic processes. Sickle cell anemia shortens the lifespan of […]

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