Why fibrosis after exposure to low frequency noise

Introduction: The cardiovascular effects of the exposure to low frequency noise (LFN) (<500 Hz) are not fully understood. Previous experimental work confirmed an increase in collagens I and III and ultrastructural changes in the intercalated discs of cardiomyocytes from rats exposed to LFN. Our work aims at characterizing the alterations in gene expression in the heart of rats exposed for 13 weeks to LFN.Materials and methods: 8 adult Wistar rats assigned randomly in equal number to continuous LFN exposure or silent conditions for control purposes were sacrificed after 13 weeks. The heart apexes were frozen and preserved at -80 oC until RNA extraction. Gene expression was analysed using GeneChip® Rat Gene 1.0 ST (Affymetrix). The set of genes was submitted to Ingenuity Pathway Analysis (IPA) software to predict relevant outcomes. For immunohistochemistry we have used samples of heart apexes fixed in formalin and embedded in paraffin and for immunofluorescence the samples were fixed in PFA 4%. In both meth...