Whole-body water spraying at 33-35°C altered forearm blood flow by 0.5 ml/min/°C, indicating skin blood flow in the neutral zone is dominated by the feedforward reflex of skin temperature.
Does whole-body temperature manipulation affect skin blood flow and core temperature in the neutral zone in humans?
Skin blood flow control in the 33-35 degree C range of skin temperature is dominated by the feedforward reflex influence of skin temperature on skin blood flow.
In humans, matching of heat loss and heat production in the "neutral" zone, defined operationally in terms of a range of skin temperatures (Tsk), is accomplished by regulation of skin blood flow (SkBF). Our studies were designed to reveal the characteristics of control of SkBF from measurements of forearm blood flow (FBF) in this zone. We controlled the temperature of water sprayed on most of the body of supine men and women at 33 or 35 degrees C in a square-wave pattern (15 min at each temperature) or a step pattern (60 min at 33 degrees C separated by short periods at 35 degrees C). FBF followed Tsk (0.5 ml.min-1.degrees C-1). Esophageal temperature changed approximately 0.11 degrees C with each 2 degrees C change in Tsk, falling with Tsk increase and vice versa. Little influence on FBF, < 0.1 ml.min-1.100 ml-1. degrees C-1, was observed when only the forearm was sprayed with 33 and 35 degrees C water. We conclude that SkBF control in the 33-35 degree C range of Tsk is dominated by the feedforward reflex influence of Tsk on SkBF. The reflex response overcompensates for the effect of Tsk on thermal balance in the neutral zone, so that equilibrium core temperature has an inverse relationship to Tsk.
Savage et al. (Mon,) reported a other. Temperature-controlled water spray on most of the body vs. Water spray on forearm only was evaluated on Forearm blood flow (FBF) and esophageal temperature changes. Whole-body water spraying at 33-35°C altered forearm blood flow by 0.5 ml/min/°C, indicating skin blood flow in the neutral zone is dominated by the feedforward reflex of skin temperature.