Researchers have studied the unusually high heart rates of shrews, one of the world’s smallest mammals, which could potentially help with human heart research.
The international team led by Aarhus University, Denmark, and the University of Manitoba, Canada, has shed light on how this phenomenon occurs, as well as how such a small animal like the shrew can maintain a high heart rate without it being lethal.
The resting heart rate of a shrew, which is not a rodent, is more than 1,000 beats per minute, whereas in mice it is 500-700, and in humans it is 60-100.
The researchers analysed the genes of a protein (cardiac troponin I) that is key to heart contraction and function, for different species, including humans and mice. They saw that animals with high heart rates have a specific gene mutation that makes this protein act as if it is always activated by adrenaline, even at rest – adrenaline is released during stress, or physical activity, and increases heart rate by providing more energy and oxygen to the muscles.
While more research is needed, these effects on cardiac troponin I could be replicated in model organisms and ‘potentially – eventually – in human hearts to mimic the beneficial effects’, said first author William Joyce, then at Aarhus and now at CNIC, Spain.
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