Quantification of cardioprotective gene expression in porcine short-term hibernating myocardium

Several cardioprotective proteins are induced during myocardial ischemia, s uch as heat shock proteins and anti-apoptotic Bcl-2-related proteins which, when experimentally overexpressed, have been shown to prevent ischemia-ind uced myocyte loss. As this pathophysiological induction is obviously not su fficient to prevent losses of myocytes, we analysed whether it could occur under moderate myocardial ischemia with hibernation, thus potentially contr ibuting to myocyte protection under these conditions. Therefore, using anes thetized Digs with documented myocardial hypoperfusion and short-term hiber nation, we investigated the left ventricular mRNA expression of the inducib le heat shock protein Hsp70 and of the anti-apoptotic Bcl-x(L) in compariso n with the pro-apoptotic Bak and Fas expression. For transcriptional analys es, the porcine cDNA sequences of Bcl-x(L), Bak and Fas were identified by polymerase chain reaction (PCR) or by screening of a porcine heart cDNA lib rary and cloned. Using reverse transcription polymerase chain reaction (RT- PCR), we observed an unchanged mRNA expression of inducible Hsp70, Bcl-x(L) , Bak and Fas after 85 min of hypoperfusion in the shortterm hibernating my ocardium, as well as after 30 min of subsequent reperfusion in the stunned myocardium, compared with transcription in a non-hypoperfused control area of the same ventricle. In conclusion. the mRNA expression of inducible Hsp7 0 and of several apoptosis-modulating proteins is not altered during modera te myocardial ischemia resulting in short-term hibernation of the affected area and during subsequent stunning. (C) 1999 Academic Press.