Steen J B, Gabrielsen G W, Kanwisher J W
Department of Biology, University of Oslo, Norway.
Acta Physiol Scand. 1988 Oct;134(2):299-304. doi: 10.1111/j.1748-1716.1988.tb08493.x.
When threatened, wild willow ptarmigan (Lagopus lagopus lagopus) hens displayed freezing behaviour, i.e. motionless, crouched with head down and eyes open. But while non-incubating hens showed increased heart (HR) (from 229 +/- 18 to 254 +/- 33 beats min-1) and ventilation rates (VR) (from 25 +/- 2 to 31 +/- 4 breaths min-1), incubating hens showed bradycardia (from 208 +/- 40 to 102 +/- 13 beats min-1) and reduced VR (from 25 +/- 2 to 10 +/- 2 breaths min-1), which could be maintained for as long as 20 min. The bradycardia response became stronger as hatching approached. The bradycardia period was interspersed by short bursts of tachycardia and hyperventilation which presumably supplied oxygen to blood and muscles. The bradycardia period was typically followed by a period of increased HR (276 +/- 104 beats min-1) and VR (32 +/- 3 breaths min-1). Atropine abolished the bradycardia response, which was thus apparently due to parasympathetic stimulation. The bradycardia response observed in incubating ptarmigan hens, during forced diving of birds and mammals and during death feigning in other animals are all examples of how emotional stimuli trigger a basic bradycardia reflex.
受到威胁时，野生柳雷鸟（Lagopus lagopus lagopus）母鸡会表现出冻结行为，即一动不动，低着头蹲着，眼睛睁开。但是，未孵蛋的母鸡心率（HR）（从229±18次/分钟增加到254±33次/分钟）和呼吸频率（VR）（从25±2次/分钟增加到31±4次/分钟）上升，而正在孵蛋的母鸡则出现心动过缓（从208±40次/分钟降至102±13次/分钟）和呼吸频率降低（从25±2次/分钟降至10±2次/分钟），这种情况可持续长达20分钟。随着孵化临近，心动过缓反应变得更强。心动过缓期会穿插着短暂的心动过速和过度换气，这大概是为血液和肌肉提供氧气。心动过缓期之后通常会出现心率增加（276±104次/分钟）和呼吸频率增加（32±3次/分钟）的时期。阿托品消除了心动过缓反应，因此这显然是由于副交感神经刺激所致。在正在孵蛋的雷鸟母鸡身上观察到的心动过缓反应，在鸟类和哺乳动物的强制潜水期间以及其他动物的假死期间，都是情绪刺激如何触发基本心动过缓反射的例子。
