Heat Acclimatization in Hot Summer for Ten Weeks Suppress the Sensitivity of Sweating in Response to Iontophoretically-administered Acetylcholine
Heat Acclimatization in Hot Summer for Ten Weeks Suppress the Sensitivity of Sweating in Response to Iontophoretically-administered Acetylcholine
- Jeong-Beom Lee
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제12권 제6호
- 등재여부 : KCI등재
- 2008.01
- 349 - 356 (8 pages)
To determine the peripheral mechanisms involved in thermal sweating during the hot summers in July before acclimatization and after acclimatization in September, we evaluated the sweating response of healthy subjects (n=10) to acetylcholine (ACh), a primary neurotransmitter involved in peripheral sudomotor sensitivity. The quantitative sudomotor axon reflex test (QSART) measures sympathetic C fiber function after iontophoresed ACh evokes a measurable reliable sweat response. The QSART, at 2 mA for 5 min with 10% ACh, was applied to determine the directly activated (DIR) and axon reflex-mediated (AXR) sweating responses during ACh iontophoresis. The AXR sweat onset-time by the axon reflex was 1.50±0.32 min and 1.84±0.46 min before acclimatization in July and after acclimatization in September, respectively (p<0.01). The sweat volume of the AXR(1) [during 5 min 10% iontophoresis] by the axon reflex was 1.45±0.53 mg/cm<sup>2</sup> and 0.98±0.24 mg/cm<sup>2</sup> before acclimati</SUP>zation in July and after acclimatization in September, respectively (p<0.001). The sweat volume of the AXR(2) [during 5 min post-iontophoresis] by the axon reflex was 2.06±0.24 mg/cm<sup>2</sup> and 1.39±0.32 mg/cm<sup>2</sup> before and after acclimatization in July and September, respectively (p<0.001). The sweat volume of the DIR was 5.88±1.33 mg/cm<sup>2</sup> and 4.98±0.94 mg/cm<sup>2</sup> before and after acclimatization in July and September, respectively (p<0.01). These findings suggest that lower peripheral sudomotor responses of the ACh receptors are indicative of a blunted sympathetic nerve response to ACh during exposure to hot summer weather conditions.