Skip to main content
OpenTrials
Active, Not Recruiting

NCT Number: NCT06633198

Heat, Microvascular Function and Aging

Vascular dysfunction is a common factor in many chronic debilitating diseases, contributing to morbidity and mortality. With the onset of chronic disease or exposure to stress, the vasculature displays an inability to adequately respond to increased blood flow demands, manifesting in a reduced ability or altered mechanism of vasodilation. Aging is an independent risk factor in the development of cardiovascular disease, and reduces vasodilator capacity, or alters the mechanism by which vasodilation occurs in multiple vascular beds. Chronic exercise/physical activity is one of the most potent ways to enhance vascular function, resulting in favorable outcomes such as reductions in blood pressure, and improved ability to perform activities of daily living. Barriers to exercise or failure of long-term adherence preclude many populations from the cardiovascular benefits of exercise, thus further enhancing cardiovascular risk. Avenues to mimic blood flow patterns observed with exercise may exert beneficial effects without the need for the ability to exercise. Recent evidence has demonstrated that passive heat therapy, or chronic heat exposure (~ +1°C in core temperature) results in reductions in major adverse cardiovascular events, blood pressure and improved large artery endothelial function, primarily through preservation of large artery function in response to vascular stress. It is unclear whether microvascular function is augmented in response to acute heat exposure, or whether this can protect against vascular insults particularly in older adults. Some preliminary evidence in humans suggest that autophagy, a cell recycling process is involved in the beneficial cardiovascular effects, as short-term heat exposure upregulates markers of autophagy. Previous evidence from our lab indicates that autophagy governs the mechanism by which microvascular vasodilation occurs. The role of autophagy in mediating the beneficial effects of passive heating is unknown.

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Conditions

Aging

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Early Phase 1

Primary location

Medical College of Wisconsin

Milwaukee, Wisconsin, 53226, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participants must be between 18-80 yrs. of age
  • No more than 1 cardiovascular risk factor (see list in exclusion criteria)

Exclusion criteria

  • Cardiovascular Risk Factors
  • Uncontrolled/unmanaged hypertension and/or use of current anti-hypertensive therapy
  • Current Tobacco product use or within last 6 months
  • BMI greater than 30
  • Hyperlipidemia - diagnosed and/or taking medications to manage
  • Hypercholesterolemia - diagnosed and/or taking medications to manage (e.g. statins)
  • Type 1 or Type 2 Diabetes
  • Use of anti-coagulant or anti-platelet drugs
  • Use of beta blockers
  • Symptomatic coronary artery disease
  • Diagnosed Heart Failure (Any classification above Class I as defined by NY Heart Association)
  • Diagnosed renal impairment Renal impairment defined, according to National Kidney Foundation as abnormalities of kidney structure or function, present for greater than 3 months, including:
  • Albuminuria (ACR ≥ 30 mg/g)
  • Urine sediment abnormalities
  • Electrolyte and other abnormalities due to tubular disorders
  • Structural abnormalities detected by imaging
  • History of kidney transplantation
  • Decreased glomerular filtration rate (GFP < 60 mL/min/1.73 m2)
  • Current Hormone Replacement Therapy Use
  • History of retinopathy
  • Documented neuromuscular disorders
  • Porphyria Cutanea Tarda (blistering of skin to sun; photosensitivity)
  • Pregnancy (Young Female subjects)
  • Allergies to povidone iodine
  • Tattoos on lower arm (forearm)
  • Use of erectile dysfunction medication in the past 6 months
  • Use of topical/non-topical steroids in last 6 months (e.g. cortisone cream)
  • Active anti-cancer treatment or treatment within last 12 months
  • Active COVID-19 or within the past 3 months
  • Gender Reassignment Therapy

Treatment and study plan

Passive heating

Procedure

The lower limbs will be immersed in warm (42C) circulating water for 60 minutes.

L-NAME

Drug

L-NAME will be used during measurement of cutaneous microvascular function to test the dependency upon NO to elicit vasodilation.

Primary outcomes

  1. Change in cutaneous microvascular function

    Time frame: Baseline, 60 minutes post I/R, and 60 minutes post hot water immersion + I/R injury

    Change in cutaneous microvascular function assessed via microdialysis infusion of acetylcholine (dose response) in the presence and absence of L-NAME to test the dependency upon NO to elicit vasodilation.

Secondary outcomes

  1. Spontaneous baroreflex sensitivity

    Time frame: Baseline, 60 minutes post I/R, 60 minutes post hot water immersion + I/R injury

    Change in spontaneous BRS

  2. 24-hour (Ambulatory) Blood Pressure

    Time frame: Baseline

    Ambulatory blood pressure (systolic, diastolic) for both peripheral and aortic blood pressure

  3. Change in plasma concentration of heat shock proteins

    Time frame: Baseline and 60 minutes post hot water immersion

    Change in the plasma concentrations of various heat shock proteins (HSP 70, 90)

Sponsors and collaborators

Lead sponsor

William Hughes

Other

Registry information

Important dates

Study start
2025
Primary completion
2028
Study completion
2028
First posted
Oct 9, 2024
Registry last updated
Jul 9, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.