Effect of changes in local skin temperature on postural vasoconstriction in man

Area of Science:

• Physiology
• Thermoregulation
• Cardiovascular Science

Background:

• Postural changes significantly influence skin blood flow, particularly in the foot.
• Understanding the interplay between local skin temperature and postural blood flow control is crucial for human physiology.

Purpose of the Study:

• To investigate the impact of local foot skin temperature alterations on postural changes in skin blood flow.
• To determine if the presence of arteriovenous anastomoses influences these temperature-dependent postural responses.

Main Methods:

• 38 healthy subjects were exposed to controlled local foot cooling (26-36°C) and warming (38-44°C) using air and a disc heater.
• Skin blood flow was measured using laser Doppler flowmetry at the foot dorsum and big toe pulp under varying postural conditions (foot at heart level and 50 cm below).

Main Results:

• The normal postural reduction in foot skin blood flow was maintained within the physiological range (26-36°C).
• At higher temperatures (38-44°C), this postural vasoconstriction was significantly attenuated or abolished.
• Similar responses were observed in areas with and without arteriovenous anastomoses.

Conclusions:

• Elevated foot skin temperatures disrupt normal postural vasoconstriction mechanisms.
• This disruption may contribute to cardiovascular maladaptation in hot environments.
• The findings highlight the sensitivity of foot circulatory regulation to temperature extremes.