Director: Dr. Brett Wong

The aim of the research in this laboratory is to better understand the cardiovascular adjustments toenvironmental and physical stressors. There are two broad areas of emphasis in this laboratory. The first areaof emphasis is aimed at understanding the neural and local control of skin blood flow in humans. Specifically,experiments are designed to address how humans increase skin blood flow during heat stress (cutaneous active vasodilation), which, along with sweating, is the primary means by which humans defend their core temperature during heat stress. The major goal of the research in this area is to determine which neurotransmitters, neuropeptides, and locally produced vasodilator substances contribute to cutaneous vasodilation during heat stress. Another goal of the skin blood flow experiments is aimed at understandingunderstanding the neuro-vascular interactions that mediate the cutaneous vascular response to locally appliedheat (termed “thermal hyperemia”). Although this response is commonly used as a non-invasive clinical tool toassess vascular function in various disease states (diabetes, cardiovascular disease), we do not know how this response is controlled. The second area of emphasis is aimed at understanding the cardiovascular responsesto changes in posture in humans. When humans stand up, blood shifts to the lower body (particularly the legs)due to the force of gravity. This blood volume shift to the legs can result in less blood returning to the heartand may result in lightheadedness, dizziness, or possibly fainting spells. This is commonly experienced byindividuals when they “stand up too quickly.” Experiments are designed to further our understanding of howhumans regulate blood pressure in response to a change in posture. My lab utilizes non-invasive, state-of-the-art techniques, including microdialysis (for delivery of drugs to the skin), laser-Doppler flowmetry (to measure skin blood flow), local skin heating, and passive whole body heat stress.

Ongoing Projects

Contribution of Sensory Nerves to Cutaneous Active Vasodilation

• To date, sensory nerves have been shown to be involved in the skin blood flow response to local stimuli (locally applied heat) but have not been believed to contribute to thermoregulatory control of skin blood flow. However, recent data suggests sensory nerves may be involved in the skin blood flow responseto whole body heat stress.
• Experiments are designed to investigate the contribution of sensory nerves and TRPV-1 channels (a component of sensory nerves) to cutaneous active vasodilation.
• Funded by University Small Research Grant, Kansas State University.
• NIH grant resubmission pending ($800,000 over 4 years)

Effect of Fish Oil Supplementation on Orthostatic Tolerance

• The inability to maintain adequate blood pressure in the upright posture is termed orthostatic intolerance. Fish oil has been shown to lower blood pressure in patients with hypertension. However,the effect of fish oil supplementation on the blood pressure response during upright posture in healthysubjects has not been investigated.
• Experiments are designed to determine the effect of fish oil supplementation to orthostatic tolerance. Subjects undergo an initial tilt table test (70° head-up tilt for 45 minutes on an automatic tilt table)before and after 7 weeks of fish oil supplementation.

Examples

MICRODIALYSIS FIBERS: Subjects are equipped with 2-4 microdialysis fibers on the forearm. Microdialysis fibers are placed by inserting a small needle just under the surface of the skin and then threading the microdialysis fiber through the needle. The needle is removed from the skin and the fiber is left in the skin. Microdialysis allows for the local delivery of pharmacological agents to the skin without any systemic (whole body) effects. We can infuse agents to block or activate certain pathways, induce vasodilation or vasoconstriction, or any combination, and investigate mechanisms of skin blood flow in up to four "experimental conditions" in one subject.

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LASER-DOPPLER PROBES: Laser-Doppler flow probes are used to measure changes in skin blood flow by shining a low powered laser light into the skin. The laser-Doppler flow probes are placed on the skin with skin tape directly over the microdialysis fibers. The combined use of laser-Doppler flow probes and microdialysis fibers is a powerful technique and allows us to study mechanisms of skin blood flow under a variety of experimental conditions.

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MICRODIALYSIS, LASER-DOPPLERS, AND INFUSION PUMPS: The microdialysis fibers are connected to syringes containing the pharmacological agents through a series of tubing. The syringes are placed in a microinfusion pump, which infuses the pharmacological agent through the microdialysis fiber at a set rate.

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WHOLE BODY HEATING: Subjects wear a tube-lined nylon suit and a plastic rain suit. The tube-lined suit is connected to a water pump and warm water is pumped through the suit (subjects do not get wet) to increase their body temperature and initiate the active vasodilator system. The rain suit prevents heat loss through sweating and helps expedite the heating process. Subjects' body temperature is monitored with a temperature-sensing wire placed under the tongue, their heart rate is monitored with an electrocardiogram (ECG), and their blood pressure is measured with an automatic blood pressure device. During the heating period, skin blood flow (laser-Doppler) is monitored and the pharmacological agents are infused through the microdialysis fibers.

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Lab contact information

Location: Room 8B Ahearn Fieldhouse

Mailing address:
Brett Wong, Ph.D.
Department of Kinesiology
1A Natatorium
Kansas State University
Manhattan, KS 66506
Phone: (785) 532-4843
Fax: (785) 532-6486
Email: bwong@ksu.edu