Re‐Evaluating Hot Mitochondria: Too Slow to Cool

AIM: ) between themselves and their cellular environment. RESULTS: > 10°C between mitochondria and their cellular environment based on MTY fluorescence intensity changes are unlikely to be reporting a signal that is uniquely intramitochondrial temperature. In addition to these analyses, we further argue that the inference mitochondria can operate at an internal temperature of > 48°C, as reported using MTY, is improbable as these internal temperatures would cause protein denaturation and aggregation and induction of the heat shock (HSR), unfolded protein (UPR), and integrated (ISR) stress responses. CONCLUSION: Taken as a whole, we conclude MTY and similar tools must be re-evaluated in regard to if they are providing solely information on local temperature and thus are so far inadequate, unto themselves, to demonstrate the existence of hot mitochondria.