Effects and Mechanism of SO2 Inhalation on Rat Myocardial Collagen Fibers

BACKGROUND This study investigates the effects and mechanism of sulfur dioxide (SO2) inhalation and exercise on rat myocardial collagen fiber. MATERIAL AND METHODS The rats were randomly divided into 4 groups: a control group (RG), an exercise group (EG), an SO2 pollution group (SRG), and an SO2 pollution and exercise group (SEG). Body weight, cardiac index, and left ventricular index in each group were compared. The myocardial hydroxyproline (Hyp) concentration was determined by pepsin acid hydrolysis. The interstitial myocardial collagen expression was measured by Sirius Red F3B in saturated carbazotic acid. The local myocardial angiotensin II type 1 receptor (AT1R) and connective tissue growth factor (CTGF) expression was tested by immunohistochemistry SABC method. RESULTS Compared with RG, the weight growth rate of EG, SRG, and SEG decreased significantly (P<0.01). Compared with EG, the body weight growth rate of SEG significantly decreased (P<0.01) and cardiac index and left ventricular index decreased but without a significant difference. Compared with EG, myocardial Hyp and collagen concentration, myocardial collagen volume fraction (CVF), perivascular collagen area (PVCA), and the expression of AT1R and CTGF in myocardium of SEG increased significantly (P<0.01). CONCLUSIONS SO2 inhalation and exercise will not only offset beneficial health effects of movement on the cardiovascular system, but also produce more unfavorable influences. People should pay attention to their environment when exercising, and try to avoid exercising in environments with SO2 pollution.