The Effect of Linagliptin on Mitochondrial and Endothelial Function

The endothelial function of the micro-circulation will be assessed by measuring the hyperemic response of the vessels in the superficial skin of the forearm after the iontophoresis of acetylcholine. The endothelium independent vasodilation will be assessed by the iontophoresis of sodium nitroprusside. Laser Doppler perfusion imaging will be used to measure relative changes in flow velocity.Visible and NIR Medical Hyperspectral Imaging (MHSI) data will be collected with a HyperMed OxyView MHSI System (HyperMed, Inc., Watertown, MA). MHSI images will be obtained from same forearm area where the iontophoresis of acetylcholine and sodium nitroprusside will be performed, before and after the iontophoresis test.

Use ultrasound to measure brachial artery flow mediated vasodilation (FMD, endothelium-dependent vasodilation) and nitroglycerin induced dilation (NID, endothelium-independent vasodilation).

Phosphorus-31 MRI data will be obtained during an exercise protocol. Muscle oxygenation will be measured using the blood oxygenation level-dependent magnetic resonance imaging (BOLD MRI) technique after induced hyperemia.