Influence of thermal balance on cold-induced vasodilation.
We examined the effect of thermal balance perturbation on cold-induced vasodilation through a dynamic A-B-A-B design applying heat (condition A) and cold (condition B) to the body's core, while the hand is exposed to a stable cold stimulus. Fifteen healthy adults (8 men, 7 women) volunteered. Applications of heat and cold were achieved through water immersions in two tanks maintained at 42 and 12 degrees C water temperature, respectively, in an A-B-A-B fashion. Throughout the experiment, the participants' right hand up to the ulnar styloid process was placed inside a temperature-controlled box set at 0 degrees C air temperature. Results demonstrated that cold-induced vasodilation occurred only during condition B and at times when body heat content was decreasing but rectal temperature had not yet dropped to baseline levels. Following the occurrence of all cold-induced vasodilation events, rectal temperature was reduced, and the phenomenon ceased when rectal temperature fell below baseline. Heart rate variability data obtained before and during cold-induced vasodilation demonstrated a shift of autonomic interaction toward parasympathetic dominance, which, however, was attributed to a sympathetic withdrawal. Receiver operating characteristics curve analyses demonstrated that the cold-induced vasodilation onset cutoff points for rectal temperature change and finger temperature were 0.62 and 16.76 degrees C, respectively. It is concluded that cold-induced vasodilation is a centrally originating phenomenon caused by sympathetic vasoconstrictor withdrawal. It is dependent on excess heat, and it may be triggered by excess heat with the purpose of preserving thermal balance.
Flouris
Andreas D
AD
Envirconmental Ergonomics Laboratory, School of Health and Human Performance, Dalhousie Unviversity, Halifax, Nova Scotia. aflouris@cereteth.gr
Cheung
Stephen S
SS
D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D005385:Fingers / Q000098:blood supply; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007700:Kinetics; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012372:ROC Curve; D012039:Regional Blood Flow / Q000502:physiology; D013147:Spirometry; D013696:Temperature; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult