title: Modulation of muscle metaboreceptor activation upon sweating and cutaneous vascular responses to rising core temperature in humans.
abstract: The present study investigated the role of muscle metaboreceptor activation on human thermoregulation by measuring core temperature thresholds and slopes for sweating and cutaneous vascular responses during passive heating associated with central and peripheral mechanisms. Six male and eight female subjects inserted their lower legs into hot water (43°C) while wearing a water perfusion suit on the upper body (34°C). One minute after immersion, an isometric handgrip exercise--40% of maximum voluntary contraction-was conducted for 1.5 min in both control and experimental conditions, while postexercise occlusion was performed in the experimental condition only for 9 min. The postexercise forearm occlusion during passive heating consistently stimulated muscle metaboreceptors, as implicated by significantly elevated mean arterial blood pressure throughout the experimental period (P <0.05). Stimulation of the forearm muscle metaboreceptors increased sweating and cutaneous vascular responses during passive heating, and was associated with significant reductions in esophageal temperature threshold of sweating and cutaneous vasodilation (Δ threshold, sweating: 0.33 ± 0.05 and 0.16 ± 0.04°C, cutaneous vascular conductance: 0.38 ± 0.08 and 0.16 ± 0.05°C for control and experimental groups, respectively, P < 0.05). The slopes of these responses were not different between the conditions. These results suggest that muscle metaboreceptor activation in the forearm accelerates sweating and cutaneous vasodilation during passive heating associated with a reduction in core temperature thresholds and may be related to central mechanisms controlling heat loss responses.
authors: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan;
authors: Tatsuro
authors: T
authors: Amano
authors: Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan;
authors: Masashi
authors: M
authors: Ichinose
authors: Laboratory for Human Performance Research, Osaka International University, Osaka, Japan;
authors: Yoshimitsu
authors: Y
authors: Inoue
authors: Institute of Health and Sports Science, University of Tsukuba, Tsukuba, Japan; and.
authors: Takeshi
authors: T
authors: Nishiyasu
authors: Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.
authors: Shunsaku
authors: S
authors: Koga
authors: Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, Kobe, Japan; kondo@kobe-u.ac.jp.
authors: Narihiko
authors: N
authors: Kondo
mesh_terms: D001833:Body Temperature Regulation; D005260:Female; D018737:Hand Strength; D006358:Hot Temperature; D006801:Humans; D007101:Immersion; D007511:Ischemia / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000294:innervation / Q000378:metabolism; D012018:Reflex; D012039:Regional Blood Flow; D011984:Sensory Receptor Cells / Q000378:metabolism*; D015398:Signal Transduction; D012867:Skin / Q000098:blood supply*; D013546:Sweating; D013997:Time Factors; D014664:Vasodilation; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water
keywords: cutaneous active vasodilation; eccrine sweat gland; group III and IV muscle afferents