IN-VIVO HEAT-SHOCK PROTECTS RAT MYOCARDIAL MITOCHONDRIA

Heat shock (HS)/stress proteins (MSP) provide protection from a variet y of stresses other than HS, including oxidative stress and mitochondr ia have been implicated as the target of MS-related protection in stre ssed cultured cells. Here we investigated whether mitochondria also ar e targets for the HS-mediated protection in vivo. Sprague Dawley rats were exposed, or not, to HS (41 degrees C, 15 min). After a 21 h recov ery period, hearts were excised and perfused with or without H2O2 (0.1 5 mM). Myocardial mitochondria were then isolated, and their oxygen co nsumption was analyzed. MS prevented H2O2-induced alterations in state 3 respiration while increasing the expression of Hsp70 and heme oxyge nase (HO). Thus, in vivo HS protects rat myocardial mitochondrial resp iration against the deleterious effects of oxidative injury, a protect ion relating to Hsp70 and/or HO and targeting state 3 respiration. (C) 1998 Academic Press.