Hyperthermia causes bovine mammary epithelial cell death by a mitochondrial-induced pathway

The effects of mild hyperthermia on bovine mammary epithelial cells exposed to 40 degrees C for 1 h were studied. The results showed that cell viability, ultrastructural features as well as mitochondrial function were significantly influenced by the mild heat treatment (40 degrees C). There was a considerate decrease in cell viability accompanied by cell loss resulting from apoptosis and necrosis followed by G(2)/M arrest. Cell death followed the typical cascade, namely decrease in the ratio of Bcl-2/Bax and mitochondrial membrane potential (Delta Psi(m)), mitochondrial swelling and caspase-3 activities dramatically increased; DNA was also damaged. In conclusion, hyperthermia depresses cell viability and induces bovine mammary cell apoptosis and necrosis through the mitochondrial-triggered cell death pathway. (c) 2007 Elsevier Ltd. All rights reserved.