Thermosensitivity of the Microvasculature: Molecular and physiological mechanisms in skeletal muscle - A narrative review.

Chronic heat stress is a potent intervention to improve vascular health, specifically within the cutaneous and skeletal muscle microcirculation. While the role of cutaneous circulation in heat dissipation is well established, emerging evidence suggests that skeletal muscle vasculature also exhibits thermosensitivity, contributing to heat-induced hyperemia beyond metabolic demand. This narrative review explores the molecular and physiological mechanisms underlying thermal hyperemia, focusing on heat-sensitive ion channels (TRPV1, TRPV4), nitric oxide (NO) signaling, and endothelial adaptations. The role of exercise-induced heat production and heat acclimation in promoting vascular plasticity is also examined, with particular emphasis on vascular remodeling and microcirculatory adaptations. Furthermore, this review highlights the pathological consequences of excessive heat exposure, including heat stroke, endothelial dysfunction, and systemic inflammation, emphasizing the delicate balance between adaptive and maladaptive vascular responses to heat stress. Understanding the interplay between heat stress, vascular regulation, and exercise adaptation provides valuable insights into potential therapeutic applications of heat acclimation for individuals with cardiovascular disease, metabolic disorders, and impaired thermoregulation.