THE RAPID EXPRESSION OF MYOCARDIAL HSP-70 MESSENGER-RNA AND THE HEAT-SHOCK 70-KDA PROTEIN CAN BE ACHIEVED AFTER ONLY A BRIEF PERIOD OF RETROGRADE HYPERTHERMIC PERFUSION

The induction of heat shock proteins in the myocardium has been sugges ted as a possible intervention to allow for enchanced cardioprotection , We have postulated that a brief period of retrograde hyperthermic pe rfusion would be sufficient to induce Hsp 70 mRNA and protein accumula tion To investigate this hypothesis, rat hearts (n=45) were perfused a t 37 degrees C for 30 min, then perfused for 15 min at 42 degrees C, a nd allowed to recover at 37 degrees C for 120 min, Control hearts (n=2 3) were perfused at 37 degrees C continuously, Northern analysis indic ated that in hearts treated with a brief period of retrograde hyperthe rmic perfusion Hsp 70 mRNA levels were increased 2.85 +/- 0.02-fold (P <0.01) by 10 min, 4.88 +/- 0.94-fold (P<0.01) by 15 min, 9.19 +/- 0.62 -fold (P<0.001) by 30 min, 9.4 +/- 0.52-fold (P<0.001) by 60 min, 9.45 +/- 0.57-fold (P<0.001) by 90 min and 9.66 +/- 0.99-fold (P<0.001) by 120 min of normothermic recovery as compared to control hearts, Weste rn analysis revealed that the heat inducible Hsp 72 kDa protein was in creased 2.37 +/- 0.45-fold (P<0.01) at 60 min, 2.53 +/- 0.25-fold (P<0 .01) at 90 min, and 2.7 +/- 0.6&-fold (P<0.01) at 120 min when compare d to control hearts, Our results indicate that the induction of the he at shock protein Hsp 70 can be rapidly achieved through retrograde hyp erthermic perfusion of the myocardium.