Volume 4 Supplement 1

15th International Conference on Environmental Ergonomics (ICEE XV)

Open Access

Peripheral thermal responses in normal and cold-sensitive individuals to sublingual Glyceryl Trinitrate (GTN)

  • Katrina Hope1Email author,
  • Clare M Eglin2,
  • Frank Golden2 and
  • Michael J Tipton2
Extreme Physiology & Medicine20154(Suppl 1):A34

https://doi.org/10.1186/2046-7648-4-S1-A34

Published: 14 September 2015

Introduction

Non-freezing cold injury (NFCI) is caused by prolonged exposure of the extremities to cold. The long-term sequelae of NFCI, include cold-sensitivity and pain[1]. The cold sensitivity is characterised by a reduction in basal skin blood flow and augmented vasoconstriction during cold exposure. We tested the hypothesis that sublingual GTN would increase blood flow in the peripheral microcirculation during and after a mild cold challenge in individuals who had not been diagnosed with NFCI, but were cold-sensitive.

Methods

In air at 30 °C, seven control and six cold-sensitive participants undertook 12 min of gentle exercise prior to immersing their right foot (protected by a thin plastic bag) into 15 °C water for 2 min, followed by 10 min of spontaneous rewarming. Two minutes prior to immersion, participants were given either 400 µg GTN or placebo sublingually in a single-blinded, counter-balanced order. Toe pad skin temperature (Tsk) and blood flow (SkBF) were measured using infrared thermography and laser Doppler flowmetry respectively.

Results

In the placebo condition, Tsk was significantly lower in Cold-sensitive participants compared to controls throughout the test (P < 0.001) as was SkBF (P < 0.05).

GTN increased the rate of rewarming (°C.min-1) and absolute Tsk of the coldest toe after the cold challenge in Cold-sensitive (placebo: 0.62(0.14) °C.min-1, 28.03(0.92) °C; GTN: 1.08(0.29) °C.min-1, 32.20(2.43) °C; p < 0.001) but not control individuals (Figure 1). GTN also increased the blood flow in the great toe during rewarming in some cold-sensitive individuals.
Figure 1

Mean (SD) T sk of coldest toe before and after foot immersion in 15 °C water in Cold-sensitive group following placebo (l) or GTN (¡) * P < 0.05, ** P < 0.001

Discussion

We accept our hypothesis that impairment in the vasodilatory response seen in individuals with cold-sensitivity can be overcome by the use of GTN, an endothelial-independent nitric oxide donor, and thereby improve the rewarming of cooled peripheral tissues.

Conclusion

Individuals with cold-sensitivity show increased vasoconstrictory tone, both at rest and during warming after a cold stimulus, compared to controls. The use of GTN to overcome this implies an abnormal endothelium and nitric oxide pathway in this condition.

Authors’ Affiliations

(1)
School of Physiology & Pharmacology, Clinical Research and Imaging Centre (CRICBristol), University of Bristol
(2)
Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth

References

  1. Ungley , Blackwood : Lancet. 1942, 2: 447-451.View ArticleGoogle Scholar

Copyright

© Hope et al.; 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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