RESUMEN
Objective To explore the relationship between left ventricular diastolic function and the dynamic changes of myocardial ultrastructure and argyrophilic fiber in diabetic rats on the different periods of lesions(week 4,12 and 24).Methods The diabetes mellitus(DM)in healthy male Sprague-Dawley rats was induced by a single injection of streptozotocin(STZ,Sigma)into intraperitoneal at a dose of 65 mg/kg body weight.The left ventricular diastolic function was measured by Color Doppler Flow Imaging-Pulsed Wave(CDFIPW)and Doppler Tissue Imaging(DTI)echocardiography.Heart tissue at the apex was obtained rapidly for transmission electron microscope study.Argyrophilic staining was used in the study of argyrophilic fiber volume fraction(APFVF)in heart interstitial tissue.Results Diastolic dysfunction of left ventricle was detected in STZinduced diabetic rats by CDFI-PW(E/A ＜ 1)at week 4,and progressed gradually.Pseudonormal filling (E/A ＞ 1)was found in diabetic rats at week 24,which could be identified by DTI(Ea/Aa ＜ 1).Diastolic function of normal rats was not impaired(E/A ＞ 1 and Ea/Aa ＞ 1).Transmission electron microscopy revealed a spectrum of subcellular remodeling in myocardium which was characterized by myofibril content decrease,disorganization,mitochondrial degeneration,sarcoplasmic reticulum,structural disorder.Compared with the control group,APFVF in myocardium was increased significantly in diabetic rats(P ＜ 0.05).Conclusion The diastolic dysfunction in STZ-induced diabetic rats correlates with damage of ultrastructure and increase of myocardial argyrophilic fiber.