Cutaneous active vasodilation in humans during passive heating postexercise.
The hypothesis that exercise causes an increase in the postexercise esophageal temperature threshold for onset of cutaneous vasodilation through an alteration of active vasodilator activity was tested in nine subjects. Increases in forearm skin blood flow and arterial blood pressure were measured and used to calculate cutaneous vascular conductance at two superficial forearm sites: one with intact alpha-adrenergic vasoconstrictor activity (untreated) and one infused with bretylium tosylate (bretylium treated). Subjects remained seated resting for 15 min (no-exercise) or performed 15 min of treadmill running at either 55, 70, or 85% of peak oxygen consumption followed by 20 min of seated recovery. A liquid-conditioned suit was used to increase mean skin temperature ( approximately 4.0 degrees C/h), while local forearm temperature was clamped at 34 degrees C, until cutaneous vasodilation. No differences in the postexercise threshold for cutaneous vasodilation between untreated and bretylium-treated sites were observed for either the no-exercise or exercise trials. Exercise resulted in an increase in the postexercise threshold for cutaneous vasodilation of 0.19 +/- 0.01, 0.39 +/- 0.02, and 0.53 +/- 0.02 degrees C above those of the no-exercise resting values for the untreated site (P < 0.05). Similarly, there was an increase of 0.20 +/- 0.01, 0.37 +/- 0.02, and 0.53 +/- 0.02 degrees C for the treated site for the 55, 70, and 85% exercise trials, respectively (P < 0.05). It is concluded that reflex activity associated with the postexercise increase in the onset threshold for cutaneous vasodilation is more likely mediated through an alteration of active vasodilator activity rather than through adrenergic vasoconstrictor activity.
Kenny
Glen P
GP
School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5. gkenny@uottawa.ca
Periard
Julien
J
Journeay
W Shane
WS
Sigal
Ronald J
RJ
Reardon
Francis D
FD
D018663:Adrenergic Agents / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001950:Bretylium Tosylate / Q000494:pharmacology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011311:Pressoreceptors / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D012881:Skin Temperature / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D018663:Adrenergic Agents; D000317:Adrenergic alpha-Antagonists; D001950:Bretylium Tosylate