We measured the salt and water balance of hatchling leatherback sea turtles, Dermochelys coriacea, during their first few days of life to investigate how they maintain homeostasis under the osmoregulatory challenge of a highly desiccating terrestrial environment and then a hyperosmotic marine environment. Hatchlings desiccated rapidly when denied access to sea water, with their hematocrit increasing significantly from 30.32+/-0.54 % to 38.51+/-1.35 % and plasma Na(+) concentration increasing significantly from 138.2+/-3.3 to 166.2+/-11.2 mmol l(-1) in 12 h. When hatchlings were subsequently put into sea water, hematocrit decreased and plasma Na(+) concentration was unchanged but both were significantly elevated above pretreatment values. In other hatchlings kept in sea water for 48 h, body mass and plasma Na(+) concentration increased significantly, but hematocrit did not increase. These data show that hatchlings were able to osmoregulate effectively and gain mass by drinking sea water. We stimulated hatchlings to secrete salt from the salt glands by injecting a salt load of 27 mmol kg(-1). The time taken for secretion to begin in newly hatched turtles was longer than that in 4-day-old hatchlings, but the secretory response was identical at 4.15+/-0.40 and 4.13+/-0.59 mmol Na(+) kg(-1) h(-1) respectively. Adrenaline and methacholine were both potent inhibitors of salt gland secretion in a dose-dependent manner, although methacholine administered simultaneously with a subthreshold salt load elicited a transient secretory response. The results showed that hatchling leatherbacks are able to tolerate significant changes in internal composition and efficiently use their salt glands to establish internal ionic and water balance when in sea water.

译文

:我们测量了刚孵化的棱皮海龟(Dermochelys coriacea)在出生后的头几天的盐和水平衡,以研究它们如何在高度干燥的陆地环境以及高渗海洋环境的渗透调节挑战下保持体内稳态。孵化场被拒绝获取海水后迅速干燥,其血细胞比容从30.32 /-0.54%显着增加到38.51 /-1.35%,血浆Na()浓度从138.2 /-3.3显着增加到166.2 /-11.2 mmol l(-1) )在12小时内。随后将孵化器放入海水中时,血细胞比容降低,血浆Na()浓度不变,但均显着高于预处理值。在海水中放置48小时的其他孵化场中,体重和血浆Na()浓度显着增加,但血细胞比容却没有增加。这些数据表明,孵化场能够有效渗透,并通过喝海水而增重。我们通过注入27 mmol kg(-1)的盐负荷来刺激幼鱼从盐腺分泌盐。新孵化的海龟开始分泌所需的时间比4天龄的幼龟要长,但分泌反应在4.15 /-0.40和4.13 /-0.59 mmol Na()kg(-1)h( -1)。肾上腺素和乙酰甲胆碱均是剂量依赖性的强效盐腺分泌抑制剂,尽管在低于阈值的盐负荷下同时施用乙酰甲胆碱会引起短暂的分泌反应。结果表明,在海水中孵化的棱皮龟能够耐受内部组成的重大变化,并能有效利用其盐腺来建立内部离子和水的平衡。

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