Fig. 6.

Impairment of vasodilatory action of insulin by palmitate is reversed by treatment with tauroursodeoxycholic acid (TUDCA; an ER stress inhibitor). Mesentery arterioles were isolated from 6-wk-old mice. Vascular activities were measured by treatment with various stimulators, including insulin (A), Ach (B), and SNP (C). Intraluminal infusion of palmitate (200 μM) impaired vasodilator action of insulin vs. BSA (control) infusion. Pretreatment with TUDCA (500 μM, 30 min before palmitate infusion) prevented the effect of palmitate. By contrast, there were no differences between groups when vessels were treated with Ach or SNP. Rresults suggest that palmitate-induced ER stress may be the mechanism to cause impairment of vasodilation in response to insulin, and attenuation of ER stress by TUDCA restores the vasodilator action of insulin. ###P < 0.001, ##P < 0.01 (TUDCA+FA vs. FA), ***P < 0.001 (FA vs. BSA).