Analysis of RNA for transcripts for catalase and SP71 in rat hearts after in vivo hyperthermia.

Hyperthermic stress induces synthesis of the major inducible (heat) stress protein (SP71) in all rat tissues. In addition, there is an increase in catalase activity in hearts at 24 and 48 h after the induction of the heat shock response. To more precisely define some of the molecular aspects of the induction of the heat shock response in hearts, we examined mRNA levels for the catalase, SP71 and HSP27. RNA was isolated from control hearts and at various time periods (0–24 h) of recovery after brief hyperthermic treatment and was analyzed by Northern blot analysis using as probes cDNA sequences for rat liver catalase, human HSP70 (inducible), and human HSP27. There was no detectable change in mRNA for catalase after heat shock or during recovery. Hyperthermic stress has no apparent effect on the regulation of transcription of mRNA coding for catalase, indicating that the increase in catalase activity is either translationally or post-translationally regulated. The human HSP70 cDNA did not hybridize to cont...