Department of Neurobiology, Physiology, & Behavior, University of California, Davis, Davis, California;
Am J Physiol Regul Integr Comp Physiol. 2013 Oct 1;305(7):R759-68. doi: 10.1152/ajpregu.00450.2012. Epub 2013 Jul 31.
Hibernating mammals undergo torpor during which blood pressure (BP), heart rate (HR), metabolic rate, and core temperature (TC) dramatically decrease, conserving energy. While the cardiovascular system remains functional, temporal changes in BP, HR, and baroreceptor-HR reflex sensitivity (BRS) over complete hibernation bouts and their relation to TC are unknown. We implanted BP/temperature telemetry transmitters into Syrian hamsters to test three hypotheses: H-1) BP, HR, and BRS decrease concurrently during entry into hibernation and increase concurrently during arousal; H-2) these changes occur before changes in TC; and H-3) the pattern of changes is consistent over successive bouts. We found: 1) upon hibernation entry, BP and HR declined before TC and BRS, suggesting baroreflex control of HR continues to regulate BP as the BP set point decreases; 2) during the later phase of entry, BRS decreased rapidly whereas BP and TC fell gradually, suggesting the importance of TC in further BP declines; 3) during torpor, BP slowly increased (but remained relatively low) without changes in HR or BRS or increased TC, suggesting minimal baroreflex or temperature influence; 4) during arousal, increased TC and BRS significantly lagged increases in BP and HR, consistent with establishment of tissue perfusion before increased TC/metabolism; and 5) the temporal pattern of these changes was similar over successive bouts in all hamsters. These results negate H-1, support H-2 with respect to BP and HR, support H-3, and indicate that the baroreflex contributes to cardiovascular regulation over a hibernation bout, albeit operating in a fundamentally different manner during entry vs. arousal.
冬眠哺乳动物在进入冬眠期间会经历体温（TC）、血压（BP）、心率（HR）和代谢率显著下降的状态，从而节约能量。虽然心血管系统仍能正常工作，但在整个冬眠过程中，BP、HR 和压力感受性反射 HR 敏感性（BRS）的时间变化及其与 TC 的关系尚不清楚。我们将血压/温度遥测发射器植入叙利亚仓鼠体内，以验证三个假设：H-1）BP、HR 和 BRS 在进入冬眠时同时下降，在觉醒时同时增加；H-2）这些变化先于 TC 发生；H-3）在连续的冬眠过程中，变化模式是一致的。我们发现：1）在进入冬眠时，BP 和 HR 先于 TC 和 BRS 下降，这表明在 BP 设定点降低时，压力反射仍继续控制 HR；2）在进入后期，BRS 迅速下降，而 BP 和 TC 则逐渐下降，这表明 TC 在进一步降低 BP 中的重要性；3）在冬眠期间，BP 缓慢升高（但仍相对较低），HR 或 BRS 或 TC 没有变化，这表明压力反射或温度影响最小；4）在觉醒期间，TC 和 BRS 的增加明显滞后于 BP 和 HR 的增加，这与在 TC/代谢增加之前建立组织灌注一致；5）在所有仓鼠中，这些变化的时间模式在连续的冬眠过程中相似。这些结果否定了 H-1，支持了 H-2 关于 BP 和 HR 的观点，支持了 H-3，并表明在进入冬眠和觉醒期间，压力反射对心血管调节有贡献，尽管其工作方式在本质上有所不同。
