Buono Michael J, Numan Travis R, Claros Ryan M, Brodine Stephanie K, Kolkhorst Fred W
Department of Biology, School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California, USA.
Am J Physiol Regul Integr Comp Physiol. 2009 Oct;297(4):R1082-5. doi: 10.1152/ajpregu.00253.2009. Epub 2009 Aug 5.
We investigated whether the eccrine sweat glands must actively produce sweat during heat acclimation if they are to adapt and increase their capacity to sweat. Eight volunteers received intradermal injections of BOTOX, to prevent neural stimulation and sweat production of the sweat glands during heat acclimation, and saline injections as a control in the contralateral forearm. Subjects performed 90 min of moderate-intensity exercise in the heat (35 degrees C, 40% relative humidity) on 10 consecutive days. Heat acclimation decreased end-exercise heart rate (156 +/- 22 vs. 138 +/- 17 beats/min; P = 0.0001) and rectal temperature (38.2 +/- 0.3 vs. 37.9 +/- 0.3 degrees C; P = 0.0003) and increased whole body sweat rate (0.70 +/- 0.29 vs. 1.06 +/- 0.50 l/h; P = 0.030). During heat acclimation, there was no measurable sweating in the BOTOX-treated forearm, but the control forearm sweat rate during exercise increased 40% over the 10 days (P = 0.040). Peripheral sweat gland function was assessed using pilocarpine iontophoresis before and after heat acclimation. Before heat acclimation, the pilocarpine-induced sweat rate of the control and BOTOX-injected forearms did not differ (0.65 +/- 0.20 vs. 0.66 +/- 0.22 mg x cm(-2) x min(-1)). However, following heat acclimation, the pilocarpine-induced sweat rate in the control arm increased 18% to 0.77 +/- 0.21 mg x cm(-2) x min(-1) (P = 0.021) but decreased 52% to 0.32 +/- 0.18 mg x cm(-2) x min(-1) (P < 0.001) in the BOTOX-treated arm. Using complete chemodenervation of the sweat glands, coupled with direct cholinergic stimulation via pilocarpine iontophoresis, we demonstrated that sweat glands must be active during heat acclimation if they are to adapt and increase their capacity to sweat.
我们研究了在热适应过程中，外分泌汗腺若要适应并提高其出汗能力，是否必须积极分泌汗液。八名志愿者接受了皮内注射肉毒杆菌毒素，以防止热适应期间汗腺的神经刺激和汗液分泌，而在对侧前臂注射生理盐水作为对照。受试者在高温环境（35摄氏度，相对湿度40%）下连续10天进行90分钟的中等强度运动。热适应使运动结束时的心率降低（156±22次/分钟对138±17次/分钟；P = 0.0001），直肠温度降低（38.2±0.3摄氏度对37.9±0.3摄氏度；P = 0.0003），并提高了全身出汗率（0.70±0.29升/小时对1.06±0.50升/小时；P = 0.030）。在热适应过程中，注射肉毒杆菌毒素的前臂没有可测量的出汗，但对照前臂在运动期间的出汗率在10天内增加了40%（P = 0.040）。在热适应前后，使用毛果芸香碱离子透入法评估外周汗腺功能。在热适应前，对照前臂和注射肉毒杆菌毒素前臂的毛果芸香碱诱导出汗率没有差异（0.65±0.20对0.66±0.22毫克·平方厘米⁻²·分钟⁻¹）。然而，热适应后，对照臂中毛果芸香碱诱导的出汗率增加了18%，达到0.77±0.21毫克·平方厘米⁻²·分钟⁻¹（P = 0.021），而在注射肉毒杆菌毒素的手臂中则降低了52%，降至0.32±0.18毫克·平方厘米⁻²·分钟⁻¹（P < 0.001）。通过完全化学去神经支配汗腺，并通过毛果芸香碱离子透入法进行直接胆碱能刺激，我们证明了汗腺在热适应过程中若要适应并提高其出汗能力，就必须保持活跃。
