Skeletal development in newborn and weanling northern elephant seals.
Skeletal development in newborn and weanling northern elephant seals.
复制标题
新生和断奶北象海豹的骨骼发育。
DOI：
10.1152/ajpregu.1994.267.3.r726
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Ortiz,CL
中科院分区：
文献类型：
--
作者：
Patterson-Buckendahl,P;Adams,SH;Morales,R;Jee,WS;Cann,CE;Ortiz,CL
北象海豹(Mironga Angustirostris)的新生期与大多数哺乳动物明显不同。紧张的1个月的哺乳期之后是2-3个月，在此期间海豹幼崽既不吃食物也不喝水。由于在此期间其他物种的骨骼发育很快，我们确定了象海豹在禁食条件下继续骨骼生长的能力。我们分析了在整个禁食期间从活体幼崽中依次获得的样本中骨转换的间接标记物[血清骨钙素和碱性磷酸酶活性以及尿钙和羟脯氨酸(Hyp)排泄]。血清骨钙素在禁食开始时较低，17~42d达到高峰，10wk后降至初始水平。碱性磷酸酶活性在禁食9wk期间呈线性增加。尿钙在9wk时相对恒定，10wk后下降，而游离Hyp和总Hyp呈线性下降。对~3H标记的Hyp的清除表明，几乎所有(>；99%)游离的Hyp都被氧化了，只有结合的Hyp被排出，对其没有降解机制。矿物质周转的直接测量--~(45)Ca清除的动力学与年轻人的结果基本相同。从自然死亡的幼鼠(通常是成年雄性造成的创伤)获得的尺骨的组织形态计量学表明，高孔骨总表面的30%到60%的活性表面(类骨和侵蚀)包含60%的骨面积/组织面积。因此，骨骼活动的所有指标都证实，尽管幼象海豹长期不摄取食物或水，但它们仍在继续骨骼发育。
The neonatal period in the northern elephant seal (Mirounga angustirostris) differs markedly from that of most mammals. An intense 1-mo nursing period is followed by 2-3 mo during which seal pups consume neither food nor water. Because skeletal development in other species is rapid during this period, we determined the capability of elephant seals to continue skeletal growth under fasting conditions. We analyzed indirect markers of bone turnover [serum osteocalcin and alkaline phosphatase activity and urinary calcium and hydroxyproline (Hyp) excretion] in samples obtained sequentially from live pups throughout the fast. Serum osteocalcin was low at the beginning of the fast, peaked between 17 and 42 days, and then decreased to initial levels after 10 wk. Alkaline phosphatase activity increased linearly through 9 wk of fasting. Urinary calcium was relatively constant through 9 wk but decreased after 10 wk, whereas free and total Hyp decreased linearly. Clearance of 3H-labeled Hyp showed that virtually all (> 99%) free Hyp was oxidized and that only bound Hyp, for which there is no degradative mechanism, was excreted. Kinetics of 45Ca clearance, a direct measurement of mineral turnover, was virtually identical to that for young humans. Histomorphometry of ulnae obtained from pups which died of natural causes (usually trauma inflicted by adult males) indicated active surfaces (osteoid plus eroded) between 30 and 60% of total surface of highly porous bone containing < 60% bone area/tissue area. Thus all indicators of skeletal activity confirmed that young elephant seals continue skeletal development, notwithstanding the prolonged period during which they take in no food or water.