Hibernating ground squirrels recycle urine to maintain their muscles

Alex Wilkins

The ground squirrel is able to stay in shape by recycling urea, the main compound in urine.

When animals are in a state of suspended animation, they use less energy and eat less. Nitrogen is an essential building block for establishing and maintaining muscle.

Matthew Regan and his colleagues at the University of Montreal have discovered how thirteen-lined ground squirrels overcome the problem. Nitrogen from urea is typically a waste product.

Regan and his team examined several groups of ground squirrels at various stages of their hibernation cycles, but gave half of the animals antibiotics. Nitrogen compounds like ammonia and glutamine were tracked all the way from the squirrel's stomach to its organs.