人在深度潛水后如果回升水面速度過快，會(huì)出現(xiàn)惡心,、身體疼痛等不適,，而海象、海獅等海洋哺乳動(dòng)物卻能在深水中自如升降，美國的一項(xiàng)新研究揭示了其中原因,。
從深水迅速上浮時(shí),，人體會(huì)因氣壓迅速下降而在血液中形成氮?dú)馀荩瑢?dǎo)致身體機(jī)能失調(diào),，醫(yī)學(xué)上稱為氣泡栓塞病,。美國斯克里普斯海洋研究所的科研人員在新一期英國期刊《生物學(xué)通訊》上報(bào)告說，他們通過長時(shí)間追蹤研究一頭海獅發(fā)現(xiàn),，這種哺乳動(dòng)物之所以能在深達(dá)數(shù)百米的水中上下自如游動(dòng),，得益于一種主動(dòng)進(jìn)行“肺萎陷”的本領(lǐng)。
研究人員捕獲這頭雌性成年海獅后,，在其身體上安裝了一枚小型記錄器,，用以實(shí)時(shí)監(jiān)測海獅體內(nèi)氣壓、下潛深度等一系列數(shù)據(jù),。此后,，研究人員將海獅放歸大海，并跟蹤研究其48次下潛捕食的情況,。
研究發(fā)現(xiàn),，在潛至約225米深時(shí)，海獅體內(nèi)的氣壓驟降,，這意味著它主動(dòng)實(shí)施“肺萎陷”,，將附著在支氣管上的大量肺泡壓縮，使整個(gè)肺部體積縮小,。這相當(dāng)于關(guān)閉了向血管輸送氣體成分的“開關(guān)”,，保證氮?dú)獾葻o法進(jìn)入血液，避免其對身體機(jī)能的侵?jǐn)_,。肺部關(guān)閉后,，海獅會(huì)通過其大量的支氣管和氣管中儲(chǔ)存的氧維持身體機(jī)能運(yùn)轉(zhuǎn)。（生物谷Bioon.com）
doi: 10.1098/rsbl.2012.0743
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Lung collapse in the diving sea lion: hold the nitrogen and save the oxygen
Birgitte I. McDonald* and Paul J. Ponganis
Lung collapse is considered the primary mechanism that limits nitrogen absorption and decreases the risk of decompression sickness in deep-diving marine mammals. Continuous arterial partial pressure of oxygen profiles in a free-diving female California sea lion (Zalophus californianus) revealed that (i) depth of lung collapse was near 225 m as evidenced by abrupt changes in during descent and ascent, (ii) depth of lung collapse was positively related to maximum dive depth, suggesting that the sea lion increased inhaled air volume in deeper dives and (iii) lung collapse at depth preserved a pulmonary oxygen reservoir that supplemented blood oxygen during ascent so that mean end-of-dive arterial was 74 ± 17 mmHg (greater than 85% haemoglobin saturation). Such information is critical to the understanding and the modelling of both nitrogen and oxygen transport in diving marine mammals.
