“Autonomic Control of the Circulation and VDR”
The study objective of this project is to examine the mechanisms of the venous distension reflex (VDR) in humans. We hypothesize that COX blockade with ketorolac tromethamine, an intravenous NSAID, will attenuate the muscle sympathetic nerve activity (MSNA) response to limb venous distension. To gain further insight into whether the COX byproducts directly stimulate chemically-sensitive afferents, or enable venodilation and indirectly evoke afferent stimulation, we will measure vein size using 3T MRI during venous distention with and without ketorolac infusions.
Wrist-to-elbow (W-E) occlusion
An IV will be inserted in the antecubital fossa of one arm. The arm will be fitted with occlusion cuffs arranged in a continuous fashion from the wrist to the elbow. A final cuff will be placed on the upper arm. The cuffs from the wrist to the elbow will be inflated to the same pressure of up to 300 mmHg using a pressurized air tank. First, the subject?s arm will be elevated and the subject will make a fist to squeeze blood from the hand. Then the wrist cuff will be inflated. Once that cuff is f ...read more on ClinicalTrials.org
Drug - ketorolac tromethamine
In the COX blockade trial, just after the Wrist-to-elbow occlusion, 6 mg ketorolac tromethamine in 10 ml saline will be infused into the forearm over 1 minute. After 10 minutes, a second infusion of ketorolac tromethamine (up to 3 mg) in 5% of the forearm volume of saline,( ~40-60 ml) will be infused into the occluded forearm at a rate of ~ 30 ml/min. Five minutes of data will then be collected before releasing the upper arm cuff. Infusion 1 is to block the COX pathway, while infusion 2 is to in ...read more on ClinicalTrials.org
Drug - saline control
In the saline control trial performed on a separate day, saline (without ketorolac) in identical volumes as those in the COX blockade trial, will be infused.
Autonomic Control of the Circulation and the Venous Distension Reflex