Passive heat stress reduces circulating endothelial and platelet microparticles

Area of Science:

• Physiology
• Cardiovascular Research
• Thermoregulation

Background:

• Circulating endothelial- and platelet-derived microparticles (EMPs and PMPs) are implicated in vascular disease and serve as biomarkers for vascular health.
• Hyperthermia can induce pro-inflammatory stress but may also offer vascular protection under non-pathological conditions.
• Understanding microparticle responses to hyperthermia is crucial for elucidating vascular adjustments during elevated body temperatures.

Purpose of the Study:

• To investigate the effect of passive heat stress (+2°C oesophageal temperature) on circulating arterial EMPs and PMPs in healthy adults.
• To determine if non-pathological hyperthermia influences concentrations of EMPs and PMPs, potentially indicating vascular changes.

Main Methods:

• Ten healthy young men were subjected to passive heat stress using a water-perfused suit, raising oesophageal temperature by approximately 2°C.
• Arterial blood samples were collected before (normothermia) and during hyperthermia.
• Concentrations of activation-derived EMPs, apoptosis-derived EMPs, and PMPs were quantified.

Main Results:

• Hyperthermia led to a marked decrease in circulating EMPs and PMPs.
• Activation-derived EMPs decreased by approximately 30%, and apoptosis-derived EMPs by approximately 45%.
• Circulating PMPs showed a significant reduction of approximately 75% in response to hyperthermia.

Conclusions:

• Passive heat stress significantly reduces circulating EMPs and PMPs in healthy adults.
• These reductions suggest potentially favorable vascular changes associated with non-pathological hyperthermia.
• The observed decrease in microparticles may contribute to the vascular improvements noted after therapeutic hyperthermia.