Jones S B
J Appl Physiol Respir Environ Exerc Physiol. 1981 May;50(5):962-6. doi: 10.1152/jappl.1981.50.5.962.
Norepinephrine (NE) turnover in myocardial tissue was measured in male golden hamsters (Mesocricetus auratus) during 1) continuous hypothermia, 2) rewarming from hypothermia initiated by exposure to 22 degrees C ambient, and 3) normothermic control state. Hypothermia was induced by exposure to 80% He-20% O2 atmosphere at 0 to -10 degrees C. At sequential periods after tritiated norepinephrine ([3H]NE) infusion, hamsters were killed by cervical transection and hearts were removed and analyzed for NE and [3H]NE content. Rate constants, turnover times, and turnover rates were determined from regression analysis of [3H]NE/micrograms NE tissue decay. Myocardial concentrations of NE were constant during NE-turnover measurements in each group. However, myocardial NE levels were reduced by 37% in both continuous hypothermia and rewarming from hypothermia compared with normothermic controls. NE turnover was highest during rewarming from hypothermia (0.34 micrograms.g-1.h-1), but no decay in myocardial [3H]NE was detectable during continuous hypothermia. Control animals had turnover values of 0.15 micrograms.g-1.h-1. Turnover data indicate severe depression in myocardial sympathetic nerve activity during hypothermia but a significant increase above normothermic control levels during rewarming from hypothermia.
在雄性金黄地鼠（Mesocricetus auratus）中，测定了心肌组织中去甲肾上腺素（NE）的周转率，实验条件如下：1）持续低温；2）从暴露于22℃环境引发的低温状态复温；3）正常体温对照状态。通过暴露于0至-10℃的80%氦-20%氧气环境诱导低温。在注入氚标记的去甲肾上腺素（[³H]NE）后的连续时间段，通过颈椎离断处死地鼠，取出心脏并分析NE和[³H]NE含量。根据[³H]NE/微克NE组织衰减的回归分析确定速率常数、周转时间和周转率。在每组NE周转率测量期间，心肌中NE的浓度保持恒定。然而，与正常体温对照组相比，持续低温和低温复温过程中心肌NE水平均降低了37%。低温复温期间NE周转率最高（0.34微克·克⁻¹·小时⁻¹），但在持续低温期间心肌[³H]NE未检测到衰减。对照动物的周转率值为0.15微克·克⁻¹·小时⁻¹。周转率数据表明，低温期间心肌交感神经活动严重受抑，但从低温复温期间显著高于正常体温对照水平。
