HIT (Hibernation Inducement Trigger) is a substance found in the blood of hibernating animals. If blood is taken from a hibernating squirrel in the winter and injected into another squirrel in the spring, the normally active squirrel goes into hibernation. HIT can be found in the blood of hibernating bears.
Researchers were able to prolong the life of an isolated pig's heart with HIT. This may have potentially important implications for organ transplant.
Also NASA became interested in HIT with an eye to long-lasting space travel.
Chemically, HIT is probably a kind of opioid.
