Myocardial infarction (MI) remodeling in insulin resistance models: Goto Kakizaki and high fat diet fed rats
Authors: Malfitano Christiane , Alba‐Loureiro Tatiana , Kuwabara Wilson Mitsuo , de Souza Leandro Ezequiel , Dourado Paulo Magno Martins , Irigoyen Maria Claudia , Curi Rui 
Published: June 2021

Myocardial infarction (MI) remodeling consequences for cardiac functions were investigated in two insulin resistance (IR) experimental models: Goto Kakisaki and high fat diet fed rats. Blood levels of FFA, total cholesterol, triglyceride, HDL cholesterol, GTT, ITT, HOMA index, blood pressure, and autonomic nervous system activity were also measured. The rats (n=8 per group) were divided into 6 groups: Wistar control (C); Wistar infarcted (CI); Goto Kakizaki ‐ GK (D); GK infarcted (DI); Wistar high fat (HF); Wistar HF infarcted (HFI). The rats were kept for 8 weeks with standard diet or high fat diet. The MI was induced by left coronary artery occlusion at the sixth week (@ 40% MI area). The GK rats exhibited impaired insulin sensitive in the GTT, ITT, and HOMA index. The HF rats did not have marked changes in the GTT and ITT but exhibited increased plasma insulin levels (HF: 0.8 ± 0.1 vs C: 0.4 ± 0.05 mg¤mL, values presented as mean ± SEM). The increased plasma insulin level in HF rats was abolished by infarction (HFI). GK rats exhibited dyslipidemia with increased plasma FFA levels (mg/mL); D: 0.85 ± 0.1; DI: 1 ± 0.1 vs C 0.4 ± 0.05), and reduced body weight gain as compared with HF rats. The GK and HF rats had increased systolic blood pressure (BP of femoral artery catheterized) as compared with control; D: 147 ± 1; DI: 144 ± 3; HF: 149 ± 2; HFI: 147 ± 3 vs C: 130 ± 0.5; CI: 122 ± 11) and the variances in BP (mmH2) and in the pulse interval (m2); LF band (low frequency = sympathetic component), whereas only the D group had the HF band (high frequency = vagal component) reduced (11 ± 1.5%) and the LF/HF balance increased (0.94 ± 0.1). The cardiac function as indicated by echocardiography was preserved after MI in HF rats as a result of the left ventricle (LV) remodeling (increase of end‐diastolic posterior wall thickness LV (LVPWd) and LVmass). The DI had diastolic dysfunction indicated by increased isovolumetric relaxation time (ms): 32 ± 1.6 vs 26 ± 2 for C and the E/A ratio (E: maximal early diastolic peak velocity and A: late peak velocity, ms) 3 ± 0.2 vs 1.9 ± 0.1 for C) and systolic dysfunction; ejection fraction (EF, %): 51 ± 3 vs 85 ± 1.4 for C and shortening fraction (%): 20 ± 1.5 vs 48 ± 1.8 for C, and increased myocardial performance index (0.78 ± 0.03 vs 0.57 ± 0.04 for C); LVPW and LVmass. The CI had reduced EF: 71 ± 3 and FS: 35 ± 2 whereas LVPWd and LVmass were increased as compared with C.

Conclusion

The non‐obese GK rats exhibited MS with high blood pressure, elevated blood glucose levels, dyslipidemia, autonomic nervous system dysfunction and IR. The HF rats also had MS with IR induced by obesity, hypertension and autonomic nervous system dysfunction. The MI remodeling preserved the cardiac function in HF rats differently of the GK animals that exhibited impaired cardiac function after MI remodeling with LV cavity enlargement.

Support or Funding Information

CAPES, CNPq, FAPESP, and The Federal University of Lavras supported this research.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.