title: The study of ISO induced heart failure rat model.
abstract: OBJECTIVE
  To find a more excellent large-dose isoproterenol (ISO) induced heart failure (HF) rat model.
  
  
  METHODS
  166 male Wistar rats were divided into four groups, normal group (n=10), 85/85 mg/kg group (n=50), 85/340 mg/kg group (n=50) and 340/340 mg/kg group (n=56). HF was induced by two subcutaneous injections of homologous ISO on 2 consecutive days. We calculated death rate of each ISO group on different time points. And all the survival ISO rats were examined by echocardiography separately on 2 weeks, 3 weeks and 4 weeks. We defined the EF<45% rats as heart failure, and calculated EF<45% rate of three ISO groups. 4 weeks after the last injection, all of the rats were sacrificed. H&E and Masson staining were used to evaluate inflammatory infiltration and myocardial fibrosis, and immunohistochemistry was used to measure the levels of IL-1, IL-6 and IL-17. We also treated adult rat cardiac fibroblasts with IL-1, IL-6, IL-17, or PBS for 24 h, and real-time PCR was used to measure the expressions of MMP-2 and MMP-9 in treated fibroblasts.
  
  
  RESULTS
  Through 4-week observation, we found that the period within 2 days after the last injection was the most dangerous one for all the ISO rats, regardless of injection dose. Then, the death rate increased slowly. 4 weeks later, the death rates were respectively 30% in 85/85 mg/kg group, 60% in 85/340 mg/kg group, and 68% in 340/340 mg/kg group, and there were statistical differences among three experimental groups. Moreover, the EF<45% rate and cardiac fibrosis rate were 100% in 85/340 mg/kg group as same as 340/340 mg/kg group, and much higher than 85/85 mg/kg group. Furthermore, we also found that pro-inflammatory cytokines (IL-1, IL-6 and IL-17) increased in 85/340 mg/kg group compared with normal group, and above cytokines could induce MMP-2 and MMP-9 expression in cardiac fibroblasts.
  
  
  CONCLUSIONS
  85/340 mg/kg ISO induced HF rat model was superior to the other two dose ISO induced HF rat models. Pro-inflammatory cytokines might contribute to HF and myocardial fibrosis through promotion of MMPs expression in cardiac fibroblasts.
authors.affiliation: Department of Cardiology, The first affiliated hospital of Harbin Medical University, Harbin, P R China, 150001.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Feng
authors.forename: Weimin
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D004452:Echocardiography; D004719:Endomyocardial Fibrosis / Q000473:pathology; D006333:Heart Failure / Q000139:chemically induced* / Q000235:genetics / Q000473:pathology; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology; D007279:Injections, Subcutaneous; D007375:Interleukin-1 / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D007545:Isoproterenol / Q000633:toxicity*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017741:Survivors
chemical_list: D007375:Interleukin-1; D020381:Interleukin-17; D015850:Interleukin-6; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D007545:Isoproterenol