# Vasomotor and Sudomotor Activity During Heat Stress in Spinal Cord Injury

> **NIH VA IK2** · SOUTH TEXAS VETERANS HEALTH CARE SYSTEM · 2020 · —

## Abstract

Sensory and motor impairment after spinal cord injury (SCI) is well studied and classified with international
standardized assessment tools. Meanwhile, autonomic impairment after SCI, is without a standardized clinical
assessment tool/exam, is challenging to treat and causes greater impairment in quality of life than paralysis
alone.1,2 One sequela of autonomic injury post SCI is thermal dysregulation. It is well accepted that persons
with spinal cord injury have impaired ability to regulate core temperature due to compromised thermoregulatory
vasomotor and sudomotor activity.3 In the setting of heat stress, impaired cutaneous vasodilation obviates skin
blood flow (SkBF) increases and prevents convective cooling while impaired sweating responses (SR)
prevents evaporative cooling. As a result, persons with SCI have difficulty maintaining thermal homeostasis,
especially under heat stress. Body cooling intervention trials performed to date have all proven minimally
successful likely due to lack of clear mechanistic understanding of autonomic change post-SCI. In non-SCI
persons, sympathetic cholinergic mechanisms that mediate efferent control of both SkBF and SR are
commonly thought to involve one and the same set of nerves; however, definitive proof is lacking. Indeed,
cholinergic vasodilator nerves and cholinergic sudomotor nerves could actually be anatomically separate.
Interestingly, it has been reported that during heat stress, persons with complete SCI have skin regions where
SkBF increases without concomitant SR increases and other regions where SR increases without concomitant
SkBF increases.7,8 These results suggest that efferent cholinergic sympathetic vasomotor nerves and efferent
cholinergic sympathetic sudomotor nerves are separate, rather one and the same. Being able to study
cholinergic vasodilator nerves and cholinergic sudomotor nerves in isolation in SCI will provide a valuable
model for thermoregulatory physiology studies in non-SCI and SCI persons, and guide next steps in
development of 1) An effective cooling technique so as to minimize heat related illness during exercise in the
SCI population with a high prevalence of cardiometabolic disease and 2) A more quantitative assessement of
thermoregulatory and autonomic function post-SCI to determine persons at greatest risk of its sequela.
OBJECTIVES - To define and test the neurological control mechanisms of sudomotor and vasomotor activity
after SCI to determine if their efferent cholinergic control is through an anatomically separate set of nerves. (1)
Map areas of vasomotor and sudomotor activity during heat stress in persons with SCI and compare
thermoregulatory level of injury (TLOI) with sensorimotor LOI. (2) Test whether increased noradrenergic
vasoconstrictor activity attenuates SkBF increases in regions that show SR increases but no SkBF increases
during whole body heat stress. (3) Test the hypothesis that cholinergic presynaptic nerve activity effects
vasomotor and/or sudo...

## Key facts

- **NIH application ID:** 9828500
- **Project number:** 5IK2RX001805-04
- **Recipient organization:** SOUTH TEXAS VETERANS HEALTH CARE SYSTEM
- **Principal Investigator:** Michelle Trbovich
- **Activity code:** IK2 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2020
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2017-01-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9828500

## Citation

> US National Institutes of Health, RePORTER application 9828500, Vasomotor and Sudomotor Activity During Heat Stress in Spinal Cord Injury (5IK2RX001805-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9828500. Licensed CC0.

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