Effects of environmental factors on heat tolerance and mechanism underlining hyperthemic hyperventilation.

我们的目的是研究环境因素对热耐受的影响，并阐明高温过度通气的机制。我们测试了这一假设，即在人类中，在休息时引起的高热呼吸过度不同于在次最大，中等强度的运动中引起的。这表明，高温呼吸确实不同，这取决于一个人是在休息还是在次最大，中等强度的运动。我们测试了这一假设，即在人类中，运动热适应（6天）改变了高温运动期间的高温呼吸过度。提示热习服虽能显著增强运动时皮肤血管舒张反应，但不影响热性呼吸过度.我们检验了这样的假设，即高温过度通气部分反映了化学感受器兴奋性O_2驱动增强，由此产生的低碳酸血症减弱了兴奋性反应和/或心肌梗死。 ...更多信息 静息状态下人类大脑动脉的平均血流速度。结果表明，在静息状态下，虽然高温增加了化学感受器呼吸性O_2驱动，但化学感受器呼吸性O_2驱动对高温过度通气的相对贡献很小（约20%），且不随核心温度的升高而改变，高温过度通气引起的低碳酸血症减少了脑血流量，但不减少呼吸性反应.本研究探讨环境因素是否影响运动时的热耐力。14名学生在高温下进行锻炼，并研究这些生理参数与家乡气候条件和空调使用情况之间的关系。出汗率、前臂皮肤血流量增加率、每分钟通气量增加率等耐热指标与气候资料之间的相关性不显著，表明近期生活方式（包括空调和运动经历）可以抵消家乡气候对耐热性的影响。少

We aimed to investigate the effects of environmental factors on heat tolerance and to elucidate the mechanisms underlining the hyperthermic hyperventilation in humans.1. We tested the hypothesis that, in humans, hyperthermic hyperpnea elicited in resting subjects differs from that elicited during submaximal, moderate intensity exercise. It was suggested that hyperthermic hyperpnea does indeed differ depending upon whether one is at rest or exercising at submaximal, moderate intensity.2. We tested the hypothesis that, in humans, exercise-heat acclimation (6-days) changes the hyperthermic hyperpnea during exercise in the heat. It was suggested that heat acclimation does not affect the hyperthermic hyperpnea, although it markedly enhances the cutaneous vasodilatory response during exercise.3. We tested the hypothesis that hyperthermic hyperventilation in part reflects enhanced chemoreceptor ventilatory 0_2 drive, and that the resultant hypocapnia attenuates ventilatory responses and/or mi … More ddle cerebral artery mean blood velocity in resting humans. It was suggested that, in resting humans, although hyperthermia increases chemoreceptor ventilatory 0_2 drive, the relative contribution of the chemoreceptor ventilatory 0_2 drive to hyperthemic hyperventilation is small (〜20%) and unchanged with increasing core temperature, and hypocapnia induced by hyperthermic hyperventilation reduces cerebral blood flow but not ventilatory responses.4. We investigated whether the environmental factors affect the heat tolerance during exercise. Fourteen students exercised in the heat and the relationships among those physiological parameters, the climate conditions of their home towns and the usage of air-conditioner. The relationships between their heat tolerance index such as the sweat rate, increase rate of skin blood flow in the forearm, the increase rate of minute ventilation and the climate data were not significant, suggesting that the recent life style including air conditioning and exercise experience could override the effects of climate of the home town on the heat tolerance in the students. Less