Role of Endothelial Function in SCI CVD Risk

The brachial artery in the non-dominant arm will be catheterized to infuse endothelium-dependent vasodilator acetylcholine, endothelium-independent vasodilator nitroprusside, and antioxidant ascorbic acid at concentrations to have isolated effect in the forearm.

Whole forearm blood flow will be measured by mercury-strain gauge while venous occlusion is applied to the forearm and hand by rapid-cuff inflation to sub-arterial pressures. Changes in whole forearm blood flow with be measured at baseline, endothelial agonists, and removal of oxidative stress via acorbic acid.

Endothelium-dependent vasodilation will then be assessed by changes in FBF in response to intra-arterial infusions of the endothelial agonist acetylcholine infused at rates of 4.0, 8.0, 16.0 μg/100 mL of forearm tissue/min to generate a dose-response curve.

Endothelium-independent vasodilation will be assessed by changes in forearm blood flow in response to intra-arterial infusions of sodium nitroprusside at 1.0, 2.0, 4.0 μg/100 mL forearm tissue/min.

Ascorbic acid will be infused at a constant rate (12 mg/100 mL tissue/min) and maintained at the same rate while the acetylcholine and sodium nitroprusside dose-response curves are repeated.

Venous blood samples will be collected to measure baseline cardiometabolic characteristics and isolate endothelial cell microvesicles for characterizations and in vitro experiments.