Baromedical Laboratory, Department of Anesthesiology, University of Texas Medical School, Houston, Texas 77030, USA.
Chronobiol Int. 2010 Jan;27(1):138-60. doi: 10.3109/07420520903398609.
In order to study circadian rhythms and decompression sickness (DCS), we determined: 1) the baseline circadian time structure in noncompressed rats of potential response variables to compression/decompression (C/D), and 2) whether rats subjected to C/D display a circadian time-dependent difference in inflammatory response intensity and biological tolerance. Subgroups of male rats, standardized to a 12 h light/12 h dark schedule, were evaluated every 4 h over 24 h after they were either compressed to 683 kPa (group E) or remained at sea level (group C). During 60 min recovery, evaluation included gross DCS symptoms and pulmonary edema in all E rats, and cell counts, nitric oxide, protein, thromboxane B(2,) and leukotriene E(4) levels in survivors. Chi-square, ANOVA, and 24 h cosinor analyses were used to test for time-of-day effects. C/D exposures near the end of dark/activity or during light/resting were generally better tolerated, with lowest signs of DCS symptoms and lowest responses by most of the variables monitored. More deaths were observed in the first half of the dark/activity span. Of the 16 subsets of inflammatory-associated variables, overall increases were observed in 13 and decreases in 2. Significant or borderline significant circadian time effects were found in 14 variables in group C, 12 variables in group E, and 13 variables in response (E%C). Thus, nearly all baseline indices of DCS demonstrated circadian time-dependencies in the sea-level exposed control rats (group C), and nearly all were modified by the circadian time of C/D. Such time-of-day effects of DCS are potentially relevant to the operational concerns of occupations involving decompression exposures and the investigation of prevention and treatment intervention strategies of DCS.
为了研究昼夜节律和减压病 (DCS)，我们确定了：1) 非加压大鼠潜在反应变量的基线昼夜时间结构，以及 2) 接受 C/D 的大鼠是否表现出炎症反应强度和生物耐受性的昼夜时间依赖性差异。雄性大鼠分组，标准化为 12 小时光照/12 小时黑暗时间表，在接受 683 kPa 加压（E 组）或保持在海平面（C 组）后 24 小时内，每 4 小时评估一次。在 60 分钟恢复期内，所有 E 组大鼠均评估大体减压病症状和肺水肿，幸存者评估细胞计数、一氧化氮、蛋白质、血栓素 B(2)和白三烯 E(4)水平。使用卡方检验、方差分析和 24 小时余弦分析来测试时间效应。接近黑暗/活动结束或在光照/休息期间进行的 C/D 暴露通常耐受性更好，减压病症状的迹象最低，大多数监测的变量反应最低。在黑暗/活动跨度的前半部分观察到更多的死亡。在 16 个炎症相关变量子集中，观察到总体增加了 13 个，减少了 2 个。在 C 组中，14 个变量、E 组中 12 个变量和反应（E%C）中 13 个变量中发现了显著或边界显著的昼夜时间效应。因此，在暴露于海平面的对照大鼠（C 组）中，几乎所有减压病的基线指数都表现出昼夜时间依赖性，并且几乎所有指数都受到 C/D 的昼夜时间的影响。减压病的这种时间效应可能与涉及减压暴露的作业的操作问题以及减压病的预防和治疗干预策略的研究有关。
