Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) are really cute when they hibernate (above). During torpor bouts, their body temperature decreases to a few degrees Celsius and their metabolism drops by as much as 95% with heart rates ranging from only 3-10 beats per minute. These bouts of torpor are interrupted by periodic arousals every couple of weeks during which their metabolism increases as body temperature elevates to 37 degrees Celsius. What is so fascinating is that they are able to decrease their body temperature below what would cause other animals to undergo cardiac arrest. Dr. Matthew Andrews at the University of Minnesota, Duluth wanted to know how these squirrels protected their hearts from a similar fate during bouts of torpor. His team characterized changes in heart proteins from animals during warm months (controls), animals in torpor as well as those aroused from torpor. They discovered that dozens of proteins show differences in their expression patterns at each of these stages in addition to novel forms of proteins found in ground squirrels. Their findings are published in the Journal of Proteome Research.
Vermillion KL, Jagtap P, Johnson JE, Griffin TJ, Andrews MT. Characterizing Cardiac Molecular Mechanisms of Mammalian Hibernation via Quantitative Proteogenomics. Journal of Proteome Research. 14:4792-804, 2015.