Potential effects of anesthetic agents on heat shock proteins in the laboratory rat

Much of the data regarding HSP70 (heat shock protein 70) responses to stress fails to exclude the potential acute effects of anesthetic agents used as part of experimental protocols. Such assumptions may not be warranted, as HSP70 responses can be rapid and vary with tissue type and type of stress. This study investigated the effects of a 30 minute exposure to three anesthetics (ketamine=KET, halothane=HAL, pentobarbital=PEN) on induction of four HSP70 family proteins (HSP72, HSC73, HSP75, GRP78). Twenty Wistar rats (Hsd:WI) were assigned to one of four groups (Control=CON, KET, PEN, HAIL) and anesthetic dosages of the appropriate agents were administered. After thirty minutes, samples (brain, liver, kidney, heart, lung, soleus, plantaris) were excised and frozen immediately in N-2. Immunoblot analyses showed that KET and PEN failed to elicit a response relative to CON regardless of analyzed tissue type. HAL induced an HSP70 response in a tissue-dependent manner; no response was elicited in the brain, mild induction was noted in muscular tissues, and strong induction was seen in the lung, kidney and liver. It is concluded that in studies assessing HSP70 concentrations, care must be taken in selecting anesthetics to avoid spurious results. This may be especially important in studies where anesthesia is used as part of a surgical protocol, pharmacological euthanasia, when laboratory animals participate in acute exercise studies, or when HSP70 is to be used as a marker of cellular or organismic distress.