Fig. 2.

Persistent insulin signaling coupled with restricted phosphatidylinositol-3 kinase (PI3K) activation causes insulin-induced vasoconstriction. A: illustration of 4 experimental conditions. B: Akt and MAPK 44/42 activation in human umbilical vein endothelial cells (HUVECs; n = 6/condition) and porcine brachial artery homogenates (whole artery; n = 5/condition). HUVECs (CC-2519, Lonza, passages 3–7 in VascuLife EnGS medium, serum starved for 24 h with 0.5% FBS) and whole artery (~5-mm segments placed in DMEM + 0.1% FBS and allowed to acclimate for 1 h at 37°C on a rocking platform) were treated with vs. without the PI3K inhibitor wortmannin (100 nM) for 48 and 3 h, respectively. Data expressed as fold difference from the PI3K inhibitor-untreated condition. C: insulin-induced dilation in isolated porcine triceps resistance arteries following treatment with vs. without the PI3K inhibitor wortmannin (100 nM) for 3 h (n = 8/condition). AUC, area under curve. D: Akt and MAPK 44/42 activation in HUVECs (n = 6/condition) and porcine brachial artery homogenates (whole artery; n = 5/condition). HUVECs and whole artery segments were treated with vs. without the PI3K inhibitor wortmannin (100 nM) for 48 and 3 h, respectively, in the presence of insulin (100 nM for HUVECs and 10 nM for whole artery). Data expressed as fold difference from the insulin-untreated and PI3K inhibitor-untreated condition in A. E: insulin-induced dilation in isolated porcine triceps resistance arteries following treatment with vs. without the PI3K inhibitor wortmannin (100 nM) for 3 h in the presence of insulin (10 nM) (n = 14/condition). F: representative Western blot images of HUVECs and whole artery segments. *P < 0.05, statistical significance from the PI3K inhibitor-untreated condition. #P < 0.05, statistical significance from the insulin-untreated condition in B. Data are expressed as means ± SE.