PERIPHERAL AND CARDIAC ADRENERGIC RESPONSE TO COLD STRESS

核心温度的微小变化已经被证明会引发 显著的肾上腺素能反应，这可能是感冒的病因， 诱发心肌缺血。 然而，以前的研究调查 这种肾上腺素能反应已经在年轻个体中进行， 年龄的影响是未知的。 此外，没有研究表明 在人类中进行，以评估阻断潜在有害的 低温的影响。 我们设计了一项研究， 年轻志愿者与老年志愿者对体温过低的反应， 肾上腺素受体拮抗剂来阻断这种反应。 这项研究于1996年6月完成，数据显示， 在寒冷的挑战中，他们不太能保持体温。 这 是由于α受体的脱敏， 在正常或甚至增加的去甲肾上腺素存在下的血管收缩 release. 寒战和全身耗氧量也受损 在老年人中，这一反应的增益降低。 老年人对阿尔法的体温调节作用更敏感 与年轻人相比， α-拮抗剂选择性损害 对核心体温过低的血管收缩反应，但不是颤抖 反应 这种选择性抑制可能在临床上有用，因为 低温对心血管的不良影响似乎 肾上腺素调节的

Small changes in core temperature have been shown to trigger a significant adrenergic response which may be the etiology of cold- induced myocardial ischemia. However, previous studies investigating this adrenergic response have been performed in young individuals, and the effects of age are unknown. In addition, no studies have been performed in humans to assess methods to block the potentially harmful effects of hypothermia. We designed a study to compare the adrenergic response to hypothermia in young vs. old human volunteers, and the use of alpha-adrenoceptor antagonists to block this response. The study was completed in June of 1996, The data show that the elderly are less able to maintain body temperature during cold challenge. This is due to a desensitization of the alpha receptor and the inability to vasocontrict in the presence of normal or even increased norepinephrine release. Shivering and total body oxygen consumption were also impaired in the elderly as demonstrated by reduced gain of this response. The elderly are more sensitive to the thermoregulatory effects of alpha blockade compared to the young. Alpha-antagonists selectively impair the vasoconstriction response to core hypothermia, but not the shivering response. This selective inhibition could be clinically useful since the adverse cardiovascular effects of hypothermia appear to be adrenergically mediated.