THE INFLUENCE OF THE COMBINED PRESENCE OF DIABETES-MELLITUS AND HYPERCHOLESTEROLEMIA ON THE FUNCTION AND MORPHOLOGY OF EXPERIMENTAL VEIN GRAFTS

Objectives: Diabetes and hypercholesterolaemia are known risk factors for the development of atherosclerosis and are considered to influence the development of vein graft intimal hyperplasia. This study examine s the combined effect of diabetes for 12 weeks (alloxan-induced) and h ypercholesterolaemia for 8 weeks (1% cholesterol diet) on the formatio n of intimal hyperplasia and the vasomotor function of vein grafts. Ma terials and design: Thirty-two New Zealand White rabbits underwent a c arotid vein bypass graft. Eight were controls, eight were diabetic, ei ght were hypercholesterolaemic and eight had both diabetes and hyperch olesterolaemia. All vein grafts were harvested at 4 weeks postoperativ ely for morphology (n = 4) or contractility studies (n = 4). Results: Compared to controls, both diabetes and hypercholesterolaemia increase d intimal thickness by 20% and 63% respectively; medial thicknesses of these vein grafts were unchanged compared to control. In contrast, di abetes with hypercholesterolaemia dramatically increased intimal and m edial thicknesses (1.8 fold and 1.6 fold respectively, compared to con trol). Smooth muscle cell contractility was enhanced in both the diabe tic and hypercholesterolaemic groups, The presence of diabetes with hy percholesterolaemia did not further alter the enhanced smooth muscle c ell contractile responses. Conclusions: This study suggests that the c ombination of both the atherogenic risk factors, hypercholesterolaemia and diabetes, significantly augments the formation of intimal hyperpl asia in experimental vein grafts.