Heat shock stress initiates simultaneous transcriptional and translational changes in the dog heart.

The acute response to heat shock was examined in the intact canine heart. Ventricular samples were removed before the dogs were heated. After heat treatment, the hearts were removed. Total RNA was extracted from pre and post heat shocked samples, translated in vitro with [35S]methionine and visualized by autoradiography. Polysome profiles from pre and post heat shocked hearts were then analyzed. Heat shocked hearts synthesized mRNAs for 71 kD stress proteins. The polysome profile after heat treatment showed a steady decline of the polysomal material toward the heavier polysome region when compared to myocardium before heat treatment. Stress protein synthesis and polysomal disaggregation are initial responses to stress that, in the mammalian heart, may be precursors to hypertrophy.