Advanced glycation end products impair KCa3.1- and KCa2.3-mediated vasodilatation via oxidative stress in rat mesenteric arteries

Abstract

The present study was designed to investigate the role of advanced glycation end products (AGEs) in intermediate-conductance and small-conductance Ca(2+)-activated potassium channels (KCa3.1 and KCa2.3)-mediated relaxation in rat resistance arteries and the underlying mechanism. The endothelial function of mesenteric arteries was assessed with the use of wire myography. Expression levels of KCa3.1 and KCa2.3 were measured by using Western blot. Reactive oxygen species (ROS) were measured by using dihydroethidium and 2', 7'-dichlorofluorescein diacetate. KCa3.1 and KCa2.3-mediated vasodilatation responses to acetylcholine and NS309 (opener of KCa3.1 and KCa2.3) were impaired by incubation of the third-order mesenteric arteries from normal rats with AGEs (200 μg ml(-1) for 3 h). In cultured human umbilical vein endothelial cells (HUVECs), AGEs increased ROS level and decreased the protein expression of KCa3.1 and KCa2.3. Antioxidant alpha lipoic acid restored the impairment in both vasodilatation function and expression of KCa3.1 and KCa2.3. H2O2 could mimic the effect of AGEs on the protein expression of KCa3.1 and KCa2.3 in cultured HUVECs. These results demonstrate for the first time that AGEs impaired KCa3.1 and KCa2.3-mediated vasodilatation in rat mesenteric arteries via downregulation of both KCa3.1 and KCa2.3, in which the enhanced oxidative stress was involved.

Metformin Restores Intermediate-Conductance Calcium-Activated K+Channel– and Small-Conductance Calcium-Activated K+Channel–Mediated Vasodilatation Impaired by Advanced Glycation End Products in Rat Mesenteric Artery

“…However, 48-hour incubation with metformin reversed AGE-induced downregulation of K Ca 3.1 and K Ca 2.3 (Fig. 4), which is in line with our previous study (Zhao et al, 2014). These results indicated that alterations of the K Ca channel both in protein expression and channel activity may be responsible for the beneficial effect of metformin on IK Ca -and SK Ca -mediated relaxation in vivo.…”

“…In our previous study, diabetic rats treated with the antioxidant alpha lipoic acid, which can quench ROS, showed the restored IK Ca -and SK Ca -mediated relaxation in mesenteric arteries . Alpha lipoic acid also attenuated AGE-induced impairment of IK Ca -and SK Ca -mediated relaxation in mesenteric arteries, and reversed AGE-induced downregulation of K Ca 3.1 and K Ca 2.3 channels in cultured HUVECs (Zhao et al, 2014). These previous studies confirmed the harmful role of ROS in IK Ca -and SK Ca -mediated relaxation.…”

“…According to our previous study, AGEs reduced the expression of K Ca 3.1 and K Ca 2.3 channels in dose-dependent and time-dependent manners (Zhao et al, 2014). We therefore investigated whether the effect of metformin on IK Ca -and SK Ca -mediated relaxation (Fig.…”

“…Our previous study showed that short-term exposure to AGE-BSA impaired EDHF-mediated relaxations in rat mesenteric arteries (Zhao et al, 2014). In this study, we also used the same method to mimic the direct effect of AGEs and observe the influence of metformin on AGE-induced impairment in rat mesenteric arteries.…”

“…AGEs are thought to impair endothelium-dependent vasodilatation in diabetes (Gao et al, 2008;Sena et al, 2012). Our previous study found that AGEs impaired IK Ca -and SK Ca -mediated relaxation in rat mesenteric arteries via downregulation of K Ca 3.1 and K Ca 2.3 channels induced by oxidative stress (Zhao et al, 2014).…”