Glucose fluctuation accelerates cardiac injury of diabetic mice via sodium-dependent glucose cotransporter 1 (SGLT1).

Recent studies have shown that blood glucose fluctuation is associated with complications of diabetes mellitus (DM). SGLT1 (sodium-dependent glucose cotransporter 1), is highly expressed in pathological conditions of heart, and is expressed in cardiomyocytes induced by high glucose. Herein, we constructed a diabetic mouse model with glucose fluctuation to investigate whether SGLT1 is involved in glucose fluctuation-induced cardiac injury. Echocardiography, histology examination, and TUNEL staining were performed to evaluate cardiac dysfunction and damage. To assess glucose fluctuation-induced oxidative stress, reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels were measured. To assess mitochondrial dysfunction, mitochondrial membrane potential (MMP), ATP content, mitochondrial respiratory chain complex activity, and expression of mitochondrial fusion and fission proteins were determined. The results indicated that diabetic mice with glucose fluctuation showed elevation of cardiac SGLT1 expression, left ventricular dysfunction, oxidative stress and mitochondrial dysfunction. Knockdown of SGLT1 could abrogate the effects of glucose fluctuation on cardiac injury. Thus, our study highlighted that SGLT1 plays an important role in glucose fluctuation induced cardiac injury through oxidative stress and mitochondrial dysfunction.