Histomorphometric evaluation of the coronary artery vessels in rats submitted to industrial noise

Introduction Industrial noise (IN) is characterized by high intensity and a wide spectrum of wavelengths that induce physical vibration on the body structures. This effect, resulting from the low-frequency sound waves, can lead to pathological alterations in the extracellular matrix with an abnormal proliferation of collagen and development of tissue fibrosis, in the absence of an inflammatory process. Objective The aim of this study was to evaluate the modifications of the arterial coronary vessels in Wistar rats submitted to IN. Methods Two groups of rats were considered: Group A with 20 rats exposed to IN during a maximum period of 7 months; group B with 20 rats as age-matched controls. The hearts were sectioned from the ventricular apex to the atria and the mid-ventricular fragment was selected. Haematoxylin-eosin and Masson's trichrome staining were used for histological observation. Histomorphometric evaluation of the coronary vessels was performed using the computer image analysis Image J software. The mean lumen-to-vessel wall (L/W) and media vessel wall-to-perivascular tissue (W/P) ratios were calculated in each group. Results Histological evaluation showed a prominent perivascular tissue with fibrotic development in the absence of inflammatory cells in group A. Histomorphometric analysis showed that the mean L/W was 0.7297 and 0.6940 in group A and B, respectively. The mean W/P ratio was 0.4923 and 0.5540 in group A and B, respectively, being higher in the control group (P < 0.01). Conclusions There are perivascular structural modifications in arterial coronary vessels. Our results show a significant development of periarterial fibrosis induced by industrial noise in the rat heart.