EFFECTS OF INTERMITTENT VS. CONSTANT HYPERGLYCAEMIA ON SAPHENOUS VEIN ENDOTHELIAL CELLS

Type 2 diabetes mellitus (T2DM) presents an increased risk of cardiovascular disease, and cardiovascular disease is a major cause of death in patients with diabetes. These vascular complications are thought to occur as a result of endothelial dysfunction, a pathological state in which endothelial cells shift towards a pro-contractile and pro-thrombotic phenotype, including a decrease in the bioavailability of the vasodilator nitric oxide (NO). Hyperglycaemia is thought to play a key role in the development of endothelial dysfunction. Research suggests that fluctuating hyperglycaemia, as experienced post-prandially, may be more damaging to the endothelium than hyperglycaemia per se. In order to assess the effects of fluctuating glucose on endothelial cell function, human saphenous vein endothelial cells (hSVECs) were exposed to either normoglycaemia (5 mM glucose), hyperglycaemia (25 mM glucose), or fluctuating glucose (cells alternately exposed to 5 mM and 25 mM glucose; 2 hour intervals) for 10 hours. Following this, cells were stimulated with 100 nM insulin, and phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), as an indicator of NO production, were assessed by western blotting. In addition, RNA was extracted from cells exposed to the different glucose conditions in order to determine any changes in gene expression of eNOS, cyclooxygenase-2 and the adhesion molecules VCAM-1 and ICAM-1. Being able to closely mimic diverse fluctuations in blood glucose experienced in vivo in patients with T2DM is vital for determining how this leads to detrimental changes in endothelial cell function, exploring the underlying mechanisms and revealing targets for therapeutic intervention.