Davenport John, Jones T Todd, Work Thierry M, Balazs George H
School of Biological, Earth and Environmental Sciences, University College Cork, North Mall Campus, Distillery Fields, Cork, Ireland
NOAA Fisheries, Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Building 176, Honolulu, HI 96818, USA.
Biol Lett. 2015 Oct;11(10). doi: 10.1098/rsbl.2015.0592.
Counter-current heat exchangers associated with appendages of endotherms feature bundles of closely applied arteriovenous vessels. The accepted paradigm is that heat from warm arterial blood travelling into the appendage crosses into cool venous blood returning to the body. High core temperature is maintained, but the appendage functions at low temperature. Leatherback turtles have elevated core temperatures in cold seawater and arteriovenous plexuses at the roots of all four limbs. We demonstrate that plexuses of the hindlimbs are situated wholly within the hip musculature, and that, at the distal ends of the plexuses, most blood vessels supply or drain the hip muscles, with little distal vascular supply to, or drainage from the limb blades. Venous blood entering a plexus will therefore be drained from active locomotory muscles that are overlaid by thick blubber when the adults are foraging in cold temperate waters. Plexuses maintain high limb muscle temperature and avoid excessive loss of heat to the core, the reverse of the accepted paradigm. Plexuses protect the core from overheating generated by muscular thermogenesis during nesting.
与恒温动物附属肢体相关的逆流热交换器具有紧密排列的动静脉血管束。公认的模式是，进入附属肢体的温暖动脉血中的热量会传递到返回身体的凉爽静脉血中。这样可以维持较高的核心体温，但附属肢体在低温下发挥作用。棱皮龟在寒冷海水中具有较高的核心体温，并且在所有四肢根部都有动静脉丛。我们证明，后肢的动静脉丛完全位于臀部肌肉组织内，并且在丛的远端，大多数血管为臀部肌肉供血或引流，很少有血管向肢体叶片远端供血或从肢体叶片远端引流。因此，当成年棱皮龟在寒冷温带水域觅食时，进入动静脉丛的静脉血将从被厚厚的脂肪覆盖的活跃运动肌肉中引流出来。动静脉丛维持较高的肢体肌肉温度，并避免热量过多散失到核心，这与公认的模式相反。动静脉丛在棱皮龟筑巢期间保护核心免受肌肉产热产生的过热影响。
