Hibernation triggers and myocardial protection

Area of Science:

• Cardiology
• Physiology
• Biochemistry

Background:

• Hypothermic cardioplegia offers myocellular protection but postischemic dysfunction persists.
• Hibernation induction trigger (HIT), a factor from hibernating animals, induces hibernation and protects against ischemia-reperfusion injury.
• Understanding HIT's cardioprotective mechanisms is crucial for improving cardiac recovery after ischemia.

Purpose of the Study:

• To investigate the cardioprotective effects of hibernation induction trigger (HIT) in ischemia-reperfusion injury.
• To determine if HIT administration improves myocardial recovery after global ischemia.
• To explore the potential role of metabolic alteration in HIT's protective effects.

Main Methods:

• Isolated rabbit hearts were subjected to 2 hours of global ischemia at 34°C.
• Hearts received either standard cardioplegia, HIT in cardioplegia, or HIT preperfusion.
• In vivo pretreatment with HIT was administered to assess metabolic alteration effects.
• Postischemic functional recovery (developed pressure, coronary flows, MVO2) and ultrastructural morphology were compared.

Main Results:

• HIT pretreatment significantly enhanced functional recovery, improving developed pressure and coronary flow compared to vehicle.
• Ultrastructural morphology was preserved with in vivo HIT pretreatment.
• HIT did not increase liver protein content, ruling out a simple protein neosynthesis mechanism.
• Temporal analysis suggested activation of an inactive HIT profactor.

Conclusions:

• Serum from hibernating animals (HIT) protects rabbit hearts against ischemia-reperfusion injury.
• HIT administration improves myocardial functional recovery and preserves tissue morphology.
• Further research is warranted to identify HIT and elucidate its protective mechanisms for therapeutic development.