Shibasaki M, Crandall C G
Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas 75231, USA.
J Appl Physiol (1985). 2001 Mar;90(3):757-62. doi: 10.1152/jappl.2001.90.3.757.
ACh is the neurotransmitter responsible for increasing sweat rate (SR) in humans. Because ACh is rapidly hydrolyzed by acetylcholinesterase (AChE), it is possible that AChE contributes to the modulation of SR. Thus the primary purpose of this project was to identify whether AChE around human sweat glands is capable of modulating SR during local application of various concentrations of ACh in vivo, as well as during a heat stress. In seven subjects, two microdialysis probes were placed in the intradermal space of the forearm. One probe was perfused with the AChE inhibitor neostigmine (10 microM); the adjacent membrane was perfused with the vehicle (Ringer solution). SR over both membranes was monitored via capacitance hygrometry during microdialysis administration of various concentrations of ACh (1 x 10(-7)-2 M) and during whole body heating. SR was significantly greater at the neostigmine-treated site than at the control site during administration of lower concentrations of ACh (1 x 10(-7)-1 x 10(-3) M, P < 0.05), but not during administration of higher concentrations of ACh (1 x 10(-2)-2 M, P > 0.05). Moreover, the core temperature threshold for the onset of sweating at the neostigmine-treated site was significantly reduced relative to that at the control site. However, no differences in SR were observed between sites after 35 min of whole body heating. These results suggest that AChE is capable of modulating SR when ACh concentrations are low to moderate (i.e., when sudomotor activity is low) but is less effective in governing SR after SR has increased substantially.
乙酰胆碱（ACh）是负责提高人体出汗率（SR）的神经递质。由于ACh会被乙酰胆碱酯酶（AChE）迅速水解，因此AChE可能参与了出汗率的调节。因此，本项目的主要目的是确定在体内局部应用不同浓度的ACh以及热应激期间，人体汗腺周围的AChE是否能够调节出汗率。在7名受试者中，将两根微透析探针置于前臂的真皮内空间。一根探针灌注乙酰胆碱酯酶抑制剂新斯的明（10微摩尔）；相邻的膜灌注赋形剂（林格溶液）。在微透析给予不同浓度的ACh（1×10⁻⁷ - 2 M）以及全身加热期间，通过电容湿度测定法监测两个膜上的出汗率。在给予较低浓度的ACh（1×10⁻⁷ - 1×10⁻³ M，P < 0.05）时，新斯的明处理部位的出汗率显著高于对照部位，但在给予较高浓度的ACh（1×10⁻² - 2 M，P > 0.05）时则不然。此外，新斯的明处理部位出汗开始的核心温度阈值相对于对照部位显著降低。然而，全身加热35分钟后，各部位之间的出汗率没有差异。这些结果表明，当ACh浓度低至中等时（即当汗腺活动较低时），AChE能够调节出汗率，但在出汗率大幅增加后，其对出汗率的控制效果较差。
