Autonomic Control of the Circulation and VDR

Summary

Participation Requirements

Description

We will use a prospective observational design to examine if a COX blockade will inhibit the MSNA response to venous distension (Aim1), and if a COX blockade will alter vein sizes during venous distension (Aim2). Each subject will serve as their own control. Aim 1: An IV will be inserted in the ante...

We will use a prospective observational design to examine if a COX blockade will inhibit the MSNA response to venous distension (Aim1), and if a COX blockade will alter vein sizes during venous distension (Aim2). Each subject will serve as their own control. Aim 1: An IV will be inserted in the antecubital fossa of one arm, and the wrist-to-elbow occlusion will be performed. To block the COX system, 6 mg ketorolac tromethamine in 10 ml saline will be infused into the forearm over 1 minute (Infusion 1). 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 (Infusion 2). 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 induce venous distension. In the saline control trial, saline (without ketorolac) in identical volumes as those in the COX blockade trial will be performed on a separate day. Aim 2: The subject will lie supine inside the MRI scanner. The subject will be instrumented with cuffs for the wrist-to-elbow occlusion procedure on one arm, and cuffs for automated BP and HR measurements from the other arm, The images will be obtained before and during the wrist-to-elbow occlusion procedure. The sizes of veins (i.e. cross sectional area) will be measured offline.

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