Rapamycin alters diaphragm calcium control

Researchers propose that rapamycin could help old mice live longer by preserving their diaphragm, the breathing muscle, against fatigue. It links FKBP12, the protein rapamycin binds, to calcium control of muscle contraction. It contrasts with the mechanistic target of rapamycin (mTOR), a regulator of cell growth and metabolism. With mitophagy blocked, a condition required for this comparison, rapamycin is predicted to preserve remaining lifespan and diaphragm endurance. Comparable genetic mTOR suppression would fail to reproduce them. The test must separate FKBP12 binding, calcium effects and mTOR suppression. A compound preserving calcium effects while leaving mTOR active should reproduce both benefits. Removing the calcium effect should abolish them despite mTOR suppression.