Butler P J, Jones D R
School of Biological Sciences, The University of Birmingham, Edgbaston, United Kingdom.
Physiol Rev. 1997 Jul;77(3):837-99. doi: 10.1152/physrev.1997.77.3.837.
This review concentrates on the physiological responses, and their control, in freely diving birds and mammals that enable them to remain submerged and sometimes quite active for extended periods of time. Recent developments in technology have provided much detailed information on the behavior of these fascinating animals. Unfortunately, the advances in technology have been insufficient to enable physiologists to obtain anything like the same level of detail on the metabolic rate and physiological adjustments that occur during natural diving. This has led to much speculation and calculations based on many assumptions concerning usable oxygen stores and metabolic rate during diving, in an attempt to explain the observed behavior. Despite their shortcomings, these calculations have provided useful insights into the degree of adaptations of various species of aquatic birds and mammals. Many of them, e.g., ducks, smaller penguins, fur seals, and Weddell seals, seem able to metabolize aerobically, when diving, at approximately the same (if not greater) rate as they do at the surface. Their enhanced oxygen stores are able to support aerobic metabolism, at what would not be considered unusually low levels, for the duration of the dives, although there are probably circulatory readjustments to ensure that the oxygen stores are managed judiciously. For other species, such as the larger penguins, South Georgian shag, and female elephant seals, there is a general consensus that they must either be reducing their aerobic metabolic rate when diving, possibly by way of regional hypothermia, and/or producing ATP, at least partly, by anaerobiosis and metabolizing the lactic acid when at the surface (although this is hardly likely in the case of the female elephant seals). Circulation is the proximate regulator of metabolism during aerobic diving, and heart rate is the best single indicator of circulatory adjustment. During voluntary dives, heart rates range from extreme bradycardia to well above resting, reflecting metabolic performance. Efferent cardiac control is largely parasympathetic. Reflex cardiorespiratory responses are modulated by conditioning and habituation, but reflexes predominate during extended dives and during recovery, when gas exchange is maximized.
本综述聚焦于自由潜水的鸟类和哺乳动物的生理反应及其调控，这些反应使它们能够长时间保持水下状态，有时还能相当活跃。技术的最新发展为这些迷人动物的行为提供了许多详细信息。不幸的是，技术进步还不足以让生理学家获得与自然潜水时代谢率和生理调节类似水平的详细信息。这导致了基于许多关于潜水时可用氧储备和代谢率假设的大量推测和计算，试图解释观察到的行为。尽管存在缺陷，但这些计算为各种水鸟和哺乳动物的适应程度提供了有用的见解。它们中的许多物种，如鸭子、较小的企鹅、海狗和威德尔海豹，在潜水时似乎能够以与在水面时大致相同（如果不是更高）的速率进行有氧代谢。它们增加的氧储备能够在潜水期间支持有氧代谢，且代谢水平并非异常低，尽管可能存在循环再调节以确保氧储备得到合理管理。对于其他物种，如较大的企鹅、南乔治亚鸬鹚和雌性海象，人们普遍认为它们在潜水时必须要么通过局部低温等方式降低有氧代谢率，和/或至少部分通过无氧呼吸产生ATP，并在水面时代谢乳酸（尽管雌性海象不太可能如此）。在有氧潜水期间，循环是代谢的直接调节因子，心率是循环调节的最佳单一指标。在自主潜水期间，心率范围从极度心动过缓到远高于静息水平，反映了代谢表现。传出性心脏控制主要是副交感神经控制。反射性心肺反应受条件作用和习惯化调节，但在长时间潜水和恢复期间，当气体交换最大化时，反射占主导地位。
