Establishment of a New Arrhythmia Model in SD Rats Induced by the Isoproterenol "6+1" Mode and Its Mechanisms

Abstract BackgroundThe main purpose is to establish an ideal arrhythmia model with isoproterenol and explore its mechanism.MethodsFifty healthy male SD rats were randomly divided into the control (CON) group, subcutaneous injection (SC) group(ISO 5 mg/kg for 2 consecutive days), intraperitoneal injection (IP) group (ISO 5 mg/kg for 2 consecutive days), 2+1 group (ISO 5mg/kg by SC for 2 consecutive days, then ISO 3mg /kg by IP for 1 day), 6+1 group ( ISO 5mg/kg by SC for 6 consecutive days, then ISO 3mg /kg by IP for 1 day).The ECG were recorded by BL-420F system. The pathological changes in myocardial tissue were observed by HE and Masson staining. The serum cTnI, TNF-α, IL-6, and IL-1β levels were detected by ELISA. Serum CK, LDH and oxidative stress-related indicators were detected by an automatic biochemical analyser. ResultsThe cardiomyocytes in the CON group rats were normal, while those in the other groups showed signs of disorder, unclear borders, and lysis and necrosis, especially in the 6+1 group. The incidence of arrhythmia, arrhythmia score, and the levels of serum myocardial enzymes, troponin, and some inflammatory factors in the 2+1 group and 6+1 group were higher than those in the single injection way (P＜0.01 or P＜0.05). The indicators in the 6+1 group were mostly higher than those in the 2+1 group (P＜0.01), and the SOD level in the 6+1 group was lower than that in the CON group; the MDA and NO higher(P＜0.01 or P＜0.05). ConclusionThe combined mode of ISO injection (SC with IP) is more likely to induce arrhythmia than single ISO injection. The "6+1" method of ISO injection can establish a more stable arrhythmia model. Cardiomyocyte damage induced by oxidative stress and inflammation is an important mechanism.