Cardiovascular and Thermal Physiology Laboratory
Director: Brett Wong, Ph.D.
Current projects in the lab are focused on understanding mechanisms by which skin blood flow increases in response to local heating (termed "cutaneous thermal hyperemia") and in response to whole body heat stress (termed "cutaneous active vasodilation"). Cutaneous thermal hyperemia is frequently used as a clinical tool to test the vascular health in various patient populations. The primary means by which humans defend against an increase in body temperature during heat stress is by increasing skin blood flow and sweating, both of which are under the control of the cutaneous active vasodilator system. We are currently investigating the role of capsaicin-sensitive afferent sensory nerves during local and whole body heating. These sensory nerves are activated by heat and capsaicin, which is the active ingredient in hot chili peppers. The goal is to understand how sensory nerves contribute to skin blood flow during local and whole body heating as well as how different molecules that are produced in the skin can activate the sensory nerves to cause skin blood flow to increase.
The lab utilizes state-of-the-art techniques, including: laser-Doppler flowmetry to measure skin blood flow; microdialysis for the local delivery of pharmacological agents to the skin; local skin heating; water-perfused suits to regulate and change body temperature; thermocouples for measuring skin temperature; head-up and head-down tilt to change posture and simulate microgravity.
Ongoing Projects in the Lab
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. Recent data suggests sensory nerves may be involved in the skin blood flow response to whole body heat stress (termed cutaneous active vasodilation) and changes in skin temperature may contribute to the increase in skin blood flow during heat stress.
- Experiments are designed to investigate the contribution of sensory nerves, TRPV channels (components of sensory nerves and blood vessels) and other substances to cutaneous active vasodilation.
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.
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.
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.
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.
Interested in being a subject?
We are always looking for individuals (both male and female) aged 18-32 who are healthy, non-smokers, and not taking any medications, with the exception of oral contraceptives, to participate in our experiments. Subjects must not have any form of cardiovascular disease (high blood pressure, high cholesterol, recent stroke or heart attack, etc.) and must not have diabetes. Reimbursement of $10 per hour is provided. If interested, please see contact information below.
Lab Contact Information
Brett Wong, Ph.D.
Department of Kinesiology
Kansas State University
Manhattan, KS 66506
(785) 532-6486 fax
Location: Room 302 Ahearn Fieldhouse