AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 5 1089-R1095, Copyright © 1989 by American Physiological Society
Atropine-induced cutaneous vasodilation decreases esophageal temperature during exercise
M. A. Kolka, L. A. Stephenson, A. E. Allan and P. B. Rock
United States Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007.
Four healthy adult males volunteered for this study, which followed
informed-consent procedures administered by our local Human Use Committee.
Esophageal (Tes) and mean skin (Tsk, eight site) temperatures, forearm
sweating rate (ms), metabolism (M), heart rate (HR), and forearm blood flow
(FBF) were measured at rest and during forearm blood flow (FBF) were
measured at rest and during exercise [55% oxygen consumption (Vo2) peak]
during control experiments and after 2 mg im atropine (ATR). Experiments
were randomized and separated by at least 72 h. ATR increased heart rate at
rest by 15 beats/min and during exercise by 24 beats/min. ATR decreased
whole body sweating by 57%. All eight local skin temperatures were higher
in ATR than in control. Tsk was 32.6 degrees C in ATR and 31.0 degrees C in
control (P less than 0.01). During exercise, ATR increased vasodilation of
the forearm compared with control. The slope of FBF to Tes increased over
300% in ATR experiments compared with control (P less than 0.05). The
higher sensible heat flux from this vasodilation decreased Tes during
exercise, which further decreased sweating. Skin blood flow remained
elevated as Tes decreased, suggesting that local vasodilatory factors
promoted atropine-induced cutaneous vasodilation.
