Gene expression profile of mouse myocardium with transgenic overexpression of A₁adenosine receptors

Transgenic mice with cardiac-specific overexpression of adenosine A(1) receptors (A(1)AR) have demonstrated metabolic and functional tolerance to myocardial ischemia. We utilized cDNA microarrays to test the hypothesis that the cardioprotective mechanism(s) of A(1) overexpression involves altered gene expression. Total RNA extracted from the left ventricles from A(1) transgenic (n = 4) and wild-type (n = 6) mice was hybridized to Affymetrix mgU74A chips. Comparison of RNA expression levels in transgenic to wild-type myocardium revealed approximately 636 known genes with expression significantly altered by greater than 25%. We observed increased expressions of genes including NADH dehydrogenase, the GLUT4 glucose transporter, Na-K-ATPase, sarcolemmal K(ATP) channels, and Bcl-xl in A(1)AR-overexpressing hearts. We also observed decreased expression of pro-apoptotic genes including a 50% reduction in message level of caspase-8. Protein expression of GLUT4 and caspase-8 was also altered comparable to the differences in gene expression. These data illustrate genes with chronically altered patterns of expression in A(1) transgenic mouse myocardium that may be related to adenosine receptor overexpression-mediated cardioprotection.