Changes of cardiac function in high-fat, high-glucose diet-induced insulin resistance in rats and telmisartan intervention study

AIM To explore cardiac functions and myocardial collagen type I in diet-induced insulin-resistant rats and the effect of telmisartan on cardiac diastolic functions in diet-induced insulin-resistant rats. METHODSTwenty-seven Wistar rats were randomized into control group, high-fat high-glucose group and telmisartan treatment group. At the end of the study, left ventricular internal pressure and -dp/dtmax were detected by carotid artery intubation. Cardiac fibrosis was observed using Masson cardiac staining and collagen volume fraction (CVF) was measured. ELISA method was used to detect the concentration of plasma PICP and ICTP. RESULTSCompared with those in control group, left ventricular end diastolic pressure in high-fat high-glucose group was significantly higher, -dP/dtmax decreased significantly, plasma PICP levels and the ratio of PICP/ICTP significantly increased and cardiac collagen volume fraction was significantly higher. After a 22-week telmisartan intervention, LVEDP and LVSP significantly decreased and -dP/dtmax significantly increased. The level of PICP and PICP/ICTP significantly decreased and left ventricular myocardial tissue collagen volume fraction content decreased. Correlation analysis showed that cardiac collagen volume fraction in insulin-resistant group was positively correlated with insulin resistance index and negatively correlated with -dp/dtmax (P<0.01). CONCLUSIONInsulin resistance promotes myocardial type I collagen synthesis, leading to increased myocardial collagen deposition and decreased cardiac diastolic function. Telmisartan may improve diastolic function partly by improving insulin resistance and reducing the deposition of myocardial collagen type I.