Insulin action in muscle and adipose tissue in type 2 diabetes:The significance of blood flow

Under normal metabolic conditions insulin stimulates microvascular perfusion(capillary recruitment) of skeletal muscle and subcutaneous adipose tissue and thus increases blood flow mainly after meal ingestion or physical exercise.This helps the delivery of insulinitself but also that of substrates and of other signalling molecules to multiple tissues beds and facilitates glucose disposal and lipid kinetics.This effect is impaired in insulin resistance and type 2 diabetes early in the development of metabolic dysregulation and reflects early-onset endothelial dysfunction.Failure of insulin to increase muscle and adipose tissue blood flow results in decreased glucose handling.In fat depots,a blunted postprandial blood flow response will result in an insufficient suppression of lipolysis and an increased spill over of fatty acids in the circulation,leading to a more pronounced insulin resistant state in skeletal muscle.This defect in blood flow response is apparent even in the prediabetic state,implying that it is a facet of insulin resistance and exists long before overt hyperglycaemia develops.The following review intends to summarize the contribution of blood flow impairment to the development of the atherogenic dysglycemia and dyslipidaemia.

A Fluorescent Glucose Transport Assay for Screening SGLT2 Inhibitors in Endogenous SGLT2-Expressing HK-2 Cells

The sodium-dependent glucose transporters 2(SGLT2)plays important role in renal reabsorption of urinal glucose back to plasma for maintaining glucose homeostasis.The approval of SGLT2 inhibitors for treatment of type 2 diabetes highlights the SGLT2 as a feasible and promising drug target in recent years.Current methods for screening SGLT2 inhibitors are complex,expensive and labor intensive.Particularly,these methods cannot directly measure nonradioactive glucose uptake in endogenous SGLT2-expressing kidney cells.In present work,human kidney cells,HK-2,was incubated with a fluorescent D-glucose derivant 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose(2-NBDG)and the fluorescent intensity of 2-NBDG was employed to measure the amount of glucose uptake into the cells.By optimizing the passages of HK-2 cells,2-NBDG concentration and incubation time,and by measuring glucose uptake treated by Dapagliflozin,a clinical drug of SGLT2 inhibitors,we successfully developed a new assay for measuring glucose uptake through SGLT2.The nonradioactive microplate and microscope-based high-throughput screening assay for measuring glucose can be a new method for screening of SGLT2 inhibitors and implied for other cell assays for glucose measurement extensively.