Regional expression of endothelin-1, ANP, IGF-1, and LV wall stress in theinfarcted rat heart

We hypothesized that myocardial infarction induces regional and temporal di fferences in endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and ins ulinlike growth factor-1 (IGF-1) gene expression that correlate with left v entricular (LV) wall stress. Echocardiography and LV pressure measurements were performed in coronary artery-ligated or sham-operated rats. Gene expre ssion was measured by competitive RT-PCR in the infarct, border zone, and r emote area and in regionally isolated cardiomyocytes. ET-1 and IGF-1 expres sion was highest in the infarcted myocardium, whereas ANP expression was hi ghest in noninfarcted myocardium. For all genes, remote area expression was highest after 7 days. At 42 days, ANP maintained maximum expression, ET-1 decreased to 50% of peak levels, and IGF-1 was normalized. Cardiomyocyte ex pression followed the same pattern as in the myocardium except for a marked ly lower IGF-1 expression. Diastolic wall stress was the best hemodynamic v ariable to predict ET-1 and ANP expression in the remote area. We conclude that ET-1, ANP, and IGF-1 are expressed in different patterns in the infarc ted heart in relation to time, functional regions, cellular distribution, a nd mechanical load.