# Ischemic preconditioning

Ischemic preconditioning (IPC) is a hormetic trick. Brief, non-lethal cycles of cutting off a tissue's oxygen, then restoring it, protect that tissue against a later, lethal loss of blood flow. Murry, Jennings, and Reimer (1986) showed it: four 5-minute coronary blockages in dogs cut the eventual heart-attack damage by about 75%. Two protection windows exist. The early phase (1 to 3 hours) runs on adenosine receptors, protein kinase C (PKC), and ATP-sensitive potassium channels (K_ATP). The late phase (12 to 24 hours) needs newly made heat-shock protein 70 and inducible nitric oxide synthase. Both windows converge on one target: they block the mitochondrial permeability transition pore (mPTP), the channel whose opening kills heart cells when blood flow returns. Remote IPC (RIPC), set off by inflating a cuff on your limb, sends protection through blood-borne mediators (nitrite, SDF-1, micro-RNAs) and nerve pathways. Aging dulls PKC signaling and K_ATP responsiveness, a deficit that caloric restriction and exercise can partly reverse. But despite consistent animal data, two large randomized trials (ERICCA, about 1,600 people; RIPHeart, about 1,400; 2015) found no benefit after heart surgery under propofol, which may interfere. So RIPC for stroke prevention or wider organ protection stays investigational.

## Sources

- Murry CE, Jennings RB, Reimer KA. (1986). Preconditioning with ischemia: a delay of lethal cell injury in ischemic myocardium. Circulation. https://doi.org/10.1161/01.cir.74.5.1124
- Yellon DM, Downey JM. (2003). Preconditioning the Myocardium: From Cellular Physiology to Clinical Cardiology. Physiological Reviews. https://doi.org/10.1152/physrev.00009.2003
- Heusch G. (2015). Molecular Basis of Cardioprotection: Signal Transduction in Ischemic Pre-, Post-, and Remote Conditioning. Circulation Research. https://doi.org/10.1161/circresaha.116.305348

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_Canonical: https://longevity-switzerland.com/en/glossary/ischemic-preconditioning · Part of Longevity Cities · Updated 2026-06-22_