Experimental Setups

To address the integrative regulation of vascular control, we employ a variety of experimental techniques, both in vivo and in vitro. The equipment used in the laboratory is state-of-the-art and provides the ability to make sophisticated and accurate measures of cardiovascular function in humans.

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  • High-resolution ultrasonography is used to image large peripheral arteries for the determination of vascular structure and function, as well as to measure regional (muscle) blood flow during various perturbations.

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  • Venous occlusion plethysmography is used to measure limb vascular responsiveness to intra-arterial administration of vasoactive drugs for the understanding of blood vessel function in human health and disease. The same system can be used to create an ischemic stimulus to test microvascular function.

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  • The Cardiocap/5 anesthesia monitor is used for heart rate and intra-arterial blood pressure recordings, as well as the precise monitoring of oxygen saturation (and other respiratory variables) during acute manipulations in systemic oxygen and carbon dioxide levels.

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  • The Finometer is used to non-invasively assess blood pressure on a beat-to-beat basis. Using modeling techniques, stroke volume can also be estimated, allowing for the calculation of cardiac output.

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  • The Rapidpoint Blood Gas analyzer allows for the rapid (<1 min) measurement of a variety of parameters in both arterial and venous blood samples. Hematocrit and hemoglobin concentration, blood gases and electrolytes are reported

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  • Various exercise ergometers are used to study the control of muscle blood flow during muscle contractions (i.e., exercise).

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  • A partial rebreathe system is used with low-oxygen medical air in order to make subjects systemically hypoxic. Using this system, we can titrate the level of oxygen in the air to achieve a range of desired saturations as well as maintain or adjust carbon dioxide levels.

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  • Our tiltable bed allows for orthostatic testing or non-invasive engagement or removal of the influence of the sympathetic nervous system on vascular control.

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  • Lower body negative pressure can be employed via suction in order to cause blood translocation and reflex activation of the sympathetic nervous system.

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  • Our cardiologists can place a catheter into the brachial artery for infusion of precise doses of pharmacology via Harvard pumps, repeated blood sampling and direct pressure measurement. The infusion of various vasodilators (increased blood flow) and vasoconstrictors (decreased blood flow) into the arterial circulation allows for local changes in the forearm vasculature, with minimal to no systemic (whole body) effects.

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  • Venous catheters provide access for blood samples and systemic drug administration. Retrograde placement is utilized to sample blood draining resting or active skeletal muscle and calculate arterial-venous differences across the tissue bed.

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  • In addition to venous catheterization, blood samples can be obtained more simply, allowing for quick access to attain samples for red blood cell isolation or blood lipid and biochemistry analysis through the Poudre Valley Hospital clinical laboratory.

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  • Microneurography is used to measure and record the direct electrical activity of peripheral sympathetic nerves, thus providing information on regional neural vasoconstriction and how this influences blood pressure regulation.

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  • Turner luminometers measure light output from the luciferin-luciferase assay for determination of ATP levels in plasma and isolated red blood cell samples obtained from our human subjects.

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  • Gravity is used to determine filterability of red cell based solution, providing an index of cell stiffness and deformability.

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