Ten days of repeated local forearm heating does not affect cutaneous vascular function

Area of Science:

• Physiology
• Thermoregulation
• Vascular Biology

Background:

• Repeated local heating is proposed to induce adaptations in the cutaneous vasculature.
• Understanding these adaptations is crucial for optimizing heat therapy and exercise protocols.

Purpose of the Study:

• To determine if 10 days of repeated local forearm heating induces peripheral adaptations in cutaneous vasculature.
• To investigate potential mechanisms of adaptation, including microvascular responsiveness to acetylcholine (ACh).
• To assess the effect of heat training on maximal forearm blood flow and dilator capacity.

Main Methods:

• 10 days of forearm exposure to 42°C water (heat) or 32°C water (control).
• Assessment of skin blood flow using laser-Doppler flowmetry and calculation of cutaneous vascular conductance (CVC).
• Microdialysis with sequential acetylcholine (ACh) infusion to assess microvascular responsiveness.
• Measurement of maximal forearm blood flow using venous occlusion plethysmography.

Main Results:

• Repeated forearm heating did not improve CVC responses to local heating or ACh infusion.
• Maximal forearm vascular conductance (FVC) remained unchanged after the heat intervention.
• No significant differences were observed in the control arm, indicating the effects were specific to the heated limb.

Conclusions:

• Ten days of repeated forearm heating is insufficient to induce significant adaptations in cutaneous vascular responsiveness in recreationally active young adults.
• The study provides novel insights into the limited impact of short-term local heat exposure on microvascular function and cholinergic sensitivity.