吉中力　張春曉　麥康森

(1．集美大學(xué)，農(nóng)業(yè)部東海海水健康養(yǎng)殖重點(diǎn)實(shí)驗(yàn)室，廈門361021；2．集美大學(xué)，廈門市飼料檢測與

安全評價重點(diǎn)實(shí)驗(yàn)室，廈門361021；3．中國海洋大學(xué)，水產(chǎn)動物營養(yǎng)與

飼料農(nóng)業(yè)部重點(diǎn)實(shí)驗(yàn)室，青島266003)

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魚類鈉離子和氯離子轉(zhuǎn)運(yùn)載體的功能及調(diào)控機(jī)制研究進(jìn)展

吉中力1張春曉2*麥康森3

(1．集美大學(xué)，農(nóng)業(yè)部東海海水健康養(yǎng)殖重點(diǎn)實(shí)驗(yàn)室，廈門361021；2．集美大學(xué)，廈門市飼料檢測與

安全評價重點(diǎn)實(shí)驗(yàn)室，廈門361021；3．中國海洋大學(xué)，水產(chǎn)動物營養(yǎng)與

飼料農(nóng)業(yè)部重點(diǎn)實(shí)驗(yàn)室，青島266003)

摘要：鈉離子(Na+)和氯離子(Cl-)不僅參與魚類體液的滲透壓平衡調(diào)節(jié)，也參與細(xì)胞膜靜息電位平衡調(diào)節(jié)，并且魚類機(jī)體內(nèi)部電解質(zhì)的穩(wěn)態(tài)也離不開Na+和Cl-的參與。位于硬骨魚類鰓、胃腸道以及腎小管上皮細(xì)胞膜上的Na+/鉀離子(K+)-ATP酶、Na+-K+-2Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白、Na+/氫離子(H+)交換蛋白、囊性纖維化跨膜調(diào)控子等相關(guān)載體蛋白，是魚類調(diào)控Na+和Cl-代謝的主要調(diào)節(jié)通道，這些調(diào)節(jié)通道蛋白的表達(dá)直接影響到機(jī)體內(nèi)電解質(zhì)的平衡。本文綜述了與魚類Na+和Cl-轉(zhuǎn)運(yùn)相關(guān)的主要載體蛋白的功能、影響其活力的因素及其調(diào)控機(jī)制等。

關(guān)鍵詞：魚類；Na+；Cl-；轉(zhuǎn)運(yùn)載體；滲透壓調(diào)節(jié)

多數(shù)情況下，硬骨魚類體液與環(huán)境處于不等滲狀態(tài)，因此需要有高效的離子滲透調(diào)節(jié)機(jī)制，以保持體內(nèi)環(huán)境的穩(wěn)態(tài)，從而保證機(jī)體所有生化生理過程的正常運(yùn)行[1]。在淡水環(huán)境中，硬骨魚類體液滲透壓高于外界水環(huán)境，其需要抵抗體內(nèi)礦物質(zhì)的流失；在海水環(huán)境中，硬骨魚類體液滲透壓低于外界水環(huán)境，其需要抵御過多鹽分所帶來的細(xì)胞脫水狀態(tài)。而廣鹽性硬骨魚類能夠更好地適應(yīng)外界水環(huán)境鹽度的變化，是由于它們有更強(qiáng)的調(diào)節(jié)體內(nèi)滲透壓的能力。眾所周知，鰓和腎臟是魚類滲透壓調(diào)節(jié)的主要器官[2-5]。然而，近年來的研究發(fā)現(xiàn)，胃腸道作為外源性營養(yǎng)物質(zhì)吸收的主要場所，其可通過攝取食物和水中電解質(zhì)來維持體內(nèi)離子的平衡[6-7]，從而參與魚類滲透壓的調(diào)節(jié)。

魚類血漿中參與滲透壓平衡調(diào)控的離子有鈉離子(Na+)、鉀離子(K+)、鈣離子(Ca2+)、鎂離子(Mg2+)、2價鐵離子(Fe2+)、銅離子(Cu2+)、錳離子(Mn2+)、鋅離子(Zn2+)、氯離子(Cl-)等[8]。而在這些離子中，Na+和Cl-濃度(Na+：165～285 meq/L；Cl-：129～270 meq/L)較高，因而其在魚類體液滲透壓調(diào)節(jié)中起主要作用[9-10]。魚類可以通過鰓吸收Na+和Cl-，亦可通過鰓將血液中過多的Na+和Cl-分泌出去。Bucking等[7]對虹鱒(Oncorhynchusmykiss)的研究發(fā)現(xiàn)，飼料中Na+和K+(約90%)主要是在胃部吸收；而對于無胃的模式魚種——側(cè)邊底鳉(Fundulusheteroclitus)，飼料中Na+的主要吸收位點(diǎn)在腸道[11]。腸道離體試驗(yàn)證實(shí)，淡水環(huán)境下鳉魚腸道對Cl-的吸收能力比海水環(huán)境下高[12-13]。另外，魚體可以通過調(diào)節(jié)腎臟對Na+和Cl-的重吸收作用，進(jìn)而調(diào)控體內(nèi)礦物質(zhì)的平衡，在海水環(huán)境中，Na+通過鰓向體外的運(yùn)輸率高于通過腎臟的運(yùn)輸率，而在淡水環(huán)境中，Na+通過鰓外流的速率會受到抑制，同時腎臟會從腎小球?yàn)V液中重吸收Na+來彌補(bǔ)自身的不足[14]。因此，鰓、胃腸道、腎臟在硬骨魚類水鹽平衡調(diào)節(jié)和滲透壓平衡調(diào)節(jié)過程中都發(fā)揮著重要作用。

Na+和Cl-的平衡調(diào)節(jié)主要是通過鰓、胃腸道和腎小管上皮載體蛋白的活力調(diào)節(jié)來實(shí)現(xiàn)，如Na+/K+ATP酶(Na+/K+-ATPase，NKA)、Na+-K+-2Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白(Na+-K+-2Cl-cotransporter，NKCC)、Na+/H+交換蛋白(Na+/H+exchanger，NHE)和囊性纖維化跨膜調(diào)控子(cystic fibrosis transmembrane conductance regulator，CFTR)等，本文對參與Na+和Cl-代謝的主要載體蛋白的功能和調(diào)控機(jī)制進(jìn)行綜述，以期為魚類滲透壓調(diào)節(jié)的研究和實(shí)踐提供理論支持。

1NKA

NKA是一種P型且包含4個α亞單位和3個β亞單位的(αβ)2蛋白[15]。作為跨膜蛋白，且作為硬骨魚類滲透調(diào)節(jié)組織中提供離子運(yùn)輸動力的一個主要的活躍泵[5]，其主要功能是將3個Na+運(yùn)出胞外，同時將2個K+運(yùn)進(jìn)胞內(nèi)(圖1和圖2)，該酶不僅可以維持細(xì)胞的內(nèi)穩(wěn)態(tài)，還可以為許多運(yùn)輸系統(tǒng)提供能量；大多數(shù)廣鹽性硬骨魚類可以通過調(diào)節(jié)NKA的活力來適應(yīng)外界環(huán)境的鹽度變化[16-21]，且不論是在海水條件下還是在淡水條件下，位于廣鹽性硬骨魚類上皮細(xì)胞基底膜外側(cè)的NKA均可形成電化學(xué)梯度來轉(zhuǎn)運(yùn)Na+和Cl-[17,22]。

眾多研究發(fā)現(xiàn)，魚類鰓的NKA對外界環(huán)境鹽度的反應(yīng)與其生態(tài)習(xí)性有關(guān)。例如：Hwang等[23]對莫桑比克羅非魚(Oreochromismossambicus)的研究表明，當(dāng)生活于自然棲息的淡水環(huán)境下時，鰓中NKA的活力最低，當(dāng)處于高滲環(huán)境下時，NKA活力則增加；Lin等[19,24]對遮目魚(Chanoschanos)的研究發(fā)現(xiàn)，在自然棲息的海水環(huán)境下，鰓中NKA的活力最低，當(dāng)處于低滲環(huán)境下時，NKA活力則增加；Kang等[25]分別對自然棲息地以淡水為主的青鳉(Oryziaslatipes)和以半咸水為主的黑點(diǎn)青鳉(Oryziasdancena)進(jìn)行研究發(fā)現(xiàn)，當(dāng)青鳉和黑點(diǎn)青鳉分別生活在海水和淡水條件下時，其鰓中NKA α亞基mRNA表達(dá)量最高，而這2種魚類分別生活在淡水和半咸水條件下時，其NKA活力和α亞基蛋白豐富度是最低的。同樣的現(xiàn)象在大馬哈魚(Oncorhynchusketa)[26]、大西洋鮭(Salmosalar)[27]、褐鱒(Salmotrutta)[28]、側(cè)邊底鳉[29]、條紋鱸(Moronesaxatilis)[30]和尼羅羅非魚(Oreochromisniloticus)[1]的研究中也有發(fā)現(xiàn)。由此可見，魚類生活在自然棲息鹽度環(huán)境下時，其鰓NKA活力最低，這也提示鰓NKA活力或許可以反映魚類對環(huán)境的適應(yīng)程度。

廣鹽性魚類可通過調(diào)節(jié)鰓中NKA的活力來適應(yīng)環(huán)境鹽度的變化，而魚類鰓中NKA活力的改變可能是其不同亞基差異表達(dá)綜合表現(xiàn)的結(jié)果。例如：Richards等[31]對虹鱒鰓中NKA中的5種不同的α亞基(α1a、α1b、α1c、α2、α3)的研究發(fā)現(xiàn)，虹鱒從淡水移到含有80%海水的水體環(huán)境后，鰓中NKAα1c和α3的mRNA表達(dá)量沒有顯著變化，而NKAα1a的mRNA表達(dá)量降低，NKAα1b的mRNA表達(dá)量則增加；馮平等[32]對不同鹽度下青鳉腸道中NKA基因表達(dá)的研究發(fā)現(xiàn)，腸道NKAα的表達(dá)在氯化鈉(NaCl)含量為5、15和25 g/L的鹽水中不變，而腸道NKAβ的表達(dá)在15和25 g/L的鹽水中被顯著抑制?？梢姡}度變化可引起鰓、腸道中NKA不同亞基的差異表達(dá)，其中腸道NKAα和β的差異表達(dá)說明NKAβ只在低滲環(huán)境下起作用，而NKAα在低滲和高滲環(huán)境下都起作用；鰓NKA的α1a、α1b的差異表達(dá)表明兩者可能分別調(diào)控魚類在低滲和高滲環(huán)境下的滲透壓平衡，這也解釋了為何廣鹽性魚類可通過NKA調(diào)節(jié)廣泛地適應(yīng)不同鹽度環(huán)境。

外界鹽度的變化不僅影響鰓中NKA的活力，也會改變魚體腸道和腎臟中NKA的表達(dá)。Seale等[33]在對莫桑比克羅非魚的研究中發(fā)現(xiàn)，海水環(huán)境下腸道NKAα的表達(dá)水平顯著高于淡水環(huán)境下。Tang等[5]在研究性成熟前的日本鰻鱺(Anguillajaponica)時發(fā)現(xiàn)，海水環(huán)境下鰓中NKAα的表達(dá)水平高于淡水環(huán)境下，而腎臟中NKAα的表達(dá)水平低于淡水環(huán)境下?？梢姡隰~類滲透壓平衡調(diào)節(jié)過程中，不僅鰓中NKA起作用，其他滲透壓調(diào)節(jié)組織中的NKA也發(fā)揮著重要作用，甚至有些魚類腸道中的NKA對鹽度改變的敏感性高于鰓中的NKA。例如：吳慶元等[34]對鯔魚(Mugilcephalus)幼魚的研究發(fā)現(xiàn)，在鹽度為20的水體環(huán)境下，鯔魚幼魚腸道中NKA活力明顯高于鰓中；Grosell[35]也認(rèn)為，在海洋魚類中，腸道中的NKA活力一般都比較高，有時甚至高于鰓中NKA的活力。外界鹽度的改變引起多個組織中NKA活力的改變，表明NKA對穩(wěn)定魚類體液滲透壓有重要作用。另外，張春曉等[36]對鱸魚(Lateolabraxjaponicus)的研究發(fā)現(xiàn)，低鎂飼料(鎂水平為0.413 g/kg)組的鱸魚在長期適應(yīng)淡水環(huán)境后，其鰓絲中NKA活力在急性鹽度脅迫1 h時顯著低于高鎂飼料(鎂水平為1.042～1.991 g/kg)組，可見長期攝食低鎂飼料會降低鱸魚鰓絲中NKA對環(huán)境鹽度刺激的敏感度，從而證實(shí)食物中離子濃度對魚體內(nèi)穩(wěn)態(tài)的維持具有重要意義。因此，在對魚類體液滲透壓調(diào)節(jié)方面的研究中，除考慮水體環(huán)境因素外，食物中的礦物元素含量也不應(yīng)忽視。

NCC：Na+/Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白 Na+/Cl-cotransporter；NHE：Na+/H+交換蛋白 Na+/H+exchanger；CFTR：囊性纖維化跨膜調(diào)控子 cystic fibrosis transmembrane conductance regulator；NKA：Na+/K+-ATP酶 Na+/K+-ATPase；NKCC1：Na+-K+-2Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白1 Na+-K+-2Cl-cotransporter 1。圖2同 The same as Fig.2。

圖1海水和淡水環(huán)境下魚鰓中泌氯細(xì)胞的形態(tài)及轉(zhuǎn)運(yùn)機(jī)制(基于McCormick[37]，略有修改)

Fig.1Morphology and transport mechanisms of gill chloride cells in seawater and

fresh water (to slightly change something based on the McCormick[37])

NKCC2：Na+-K+-2Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白2 Na+-K+-2Cl-cotransporter 2；NHE3：Na+/H+交換蛋白 Na+/H+exchanger 3。

圖2魚腸道中離子交換轉(zhuǎn)運(yùn)機(jī)制概念模型(基于Grosell等[38]，略有修改)

Fig.2Conceptual model of transport processes involved in intestinal ions exchange in

fish (to slightly change something based on the Grosell, et al[38])

2NKCC和NCC

作為溶質(zhì)轉(zhuǎn)運(yùn)體12A(SLC12A)蛋白家族的一員，NKCC是一種膜蛋白，位于上皮細(xì)胞膜的頂端或基底側(cè)，主要作用是對離子的吸收和分泌，即負(fù)責(zé)同時將1分子的Na+、1分子的K+和2分子的Cl-通過它們的電化學(xué)梯度轉(zhuǎn)移至上皮細(xì)胞內(nèi)[39-42](圖1和圖2)。在魚類中已確定NKCC有2個亞型，分別是位于細(xì)胞基底外側(cè)的NKCC1(作用是向體外分泌離子)和位于細(xì)胞頂膜的NKCC2(作用是向體內(nèi)吸收離子)，因而當(dāng)魚體內(nèi)的細(xì)胞處于高滲環(huán)境下時，可激活NKCC1通過細(xì)胞向外界分泌離子來調(diào)節(jié)細(xì)胞內(nèi)外滲透壓的平衡(圖1)[16,43]。有學(xué)者已從歐洲鰻鱺(Anguillaanguilla)[43]和莫桑比克羅非魚[44]體內(nèi)克隆出NKCC1基因的2個亞型，即NKCC1a和NKCC1b基因。在硬骨魚類中，NKCC1a基因在大部分的組織中都有表達(dá)，而NKCC1b基因則主要在大腦中表達(dá)[45]。另外，NKCC2基因主要在腸道和腎臟上皮細(xì)胞頂膜處表達(dá)[33,43-44,46]，如Tresguerres等[47]研究發(fā)現(xiàn)，在海洋硬骨魚類的腸道中，NaCl從腸腔內(nèi)吸收進(jìn)入腸壁細(xì)胞主要是通過頂膜的NKCC2途徑。

多數(shù)研究發(fā)現(xiàn)，改變水體鹽度可以影響魚體組織中NKCC基因的表達(dá)。例如，側(cè)邊底鳉在從淡水轉(zhuǎn)移至海水后，鰓上皮細(xì)胞中NKCC1的mRNA表達(dá)量增加[29,48]。當(dāng)薩羅羅非魚(Sarotherodonmelanothern)生活于136鹽度環(huán)境下時，其鰓中NKCC1a的mRNA表達(dá)量極顯著高于0鹽度環(huán)境下[49]。另外，Hiroi等[50]在對3種鮭科魚類[湖紅點(diǎn)鮭(Salvelinusnamaycush)、美洲紅點(diǎn)鮭(Salvelinusfontinalis)和大西洋鮭]的研究中發(fā)現(xiàn)，隨著外界環(huán)境鹽度的升高，3種魚鰓中NKCC基因的表達(dá)呈現(xiàn)上調(diào)的趨勢，這與NKA活力的變化趨勢相同。Lorin-Nebel等[51]采用分子生物學(xué)方法對歐洲鱸魚(Dicentrarchuslabrax)不同組織中NKCC1基因分析后發(fā)現(xiàn)，淡水環(huán)境下，鱸魚鰓中NKCC1的mRNA表達(dá)量顯著低于海水環(huán)境下，而后腎和后腸中NKCC(NKCC1和NKCC2)的mRNA表達(dá)量受水體鹽度的影響不大。同時，范武江等[49]研究也發(fā)現(xiàn)，136鹽度環(huán)境下薩羅羅非魚鰓中NKCC1a的mRNA表達(dá)量極顯著高于腸道和腎臟中，說明鰓是魚類在海水環(huán)境中向外分泌離子的主要部位。Cutler等[43]對歐洲鰻的研究發(fā)現(xiàn)，當(dāng)非遷徙的黃鰻(性成熟前的歐洲鰻鱺腹部為黃色)移至海水環(huán)境下2 d時，其鰓中NKCC1a的mRNA表達(dá)量上調(diào)了4.3倍，而且3周后達(dá)到近6倍高，而腎臟和中腸中NKCC1a的mRNA表達(dá)量則均有所降低；對于性成熟的銀鰻(性成熟后的歐洲鰻鱺腹部為銀色)，移至海水環(huán)境下其鰓中NKCC1a的mRNA表達(dá)量并沒有顯著差異，而腎臟中NKCC1a的mRNA表達(dá)量在下調(diào)，且顯著低于海水環(huán)境下黃鰻腎臟中NKCC1a的mRNA表達(dá)量；此外，中腸中NKCC1a的mRNA表達(dá)量和移至海水環(huán)境后的黃鰻相比無顯著差異?？梢?，當(dāng)歐洲鰻處于高滲環(huán)境下時，鰓中NKCC1a向外分泌過多的鹽，進(jìn)而調(diào)節(jié)體液滲透壓平衡，而腸道和腎小管通過NKCC1a分泌鹽的能力相對較低，而且不同的生態(tài)習(xí)性也會影響歐洲鰻組織中NKCC1a的mRNA表達(dá)。除了水體鹽度外，一些激素也會影響組織中NKCC基因的表達(dá)。Tipsmark等[28]采用離體試驗(yàn)對棕鱒(Salmotrutta)和大西洋鮭研究發(fā)現(xiàn)，皮質(zhì)醇可以直接刺激鰓中NKCC1的mRNA表達(dá)。Seale等[33]對莫桑比克羅非魚的研究發(fā)現(xiàn)，由腦垂體分泌的催乳素可以調(diào)控腸道中NKCC2的mRNA表達(dá)，從而適應(yīng)外界環(huán)境鹽度的變化。

一些淡水魚類的滲透壓組織和卵黃囊膜頂膜中存在另一種SLC12A蛋白家族成員，即Na+/Cl-協(xié)同轉(zhuǎn)運(yùn)蛋白(NCC)(圖1和圖2)，其可以同時促進(jìn)Na+和Cl-的吸收，是一種電中性的離子轉(zhuǎn)運(yùn)蛋白，在海水適應(yīng)過程中，NCC活力較低[44,52-54]。邵占濤[52]在鱸魚的研究中發(fā)現(xiàn)，魚體進(jìn)入淡水環(huán)境后，鰓、腸道、腎臟組織中NCC的mRNA表達(dá)量顯著高于海水環(huán)境下，且在第3天達(dá)到最大值。Hiroi等[44]對莫桑比克羅非魚的研究發(fā)現(xiàn)，魚體進(jìn)入淡水環(huán)境后，鰓中NCC的mRNA表達(dá)量顯著高于海水環(huán)境下。此外，Inokuchi等[55]對莫桑比克羅非魚的研究發(fā)現(xiàn)，當(dāng)莫桑比克羅非魚生活于“正常Na+/低Cl-”環(huán)境中時，其鰓中NCC的mRNA表達(dá)量相對于對照組(生活于“正常Na+/正常Cl-”環(huán)境中)顯著增加，可見NCC的主要功能是促進(jìn)Cl-的吸收。有研究指出，位于基底膜外側(cè)的NKCC1a主要在海水環(huán)境下表達(dá)，起向體外分泌離子的作用且存在于Ⅳ型富含線粒體的細(xì)胞中；而位于頂膜的NCC主要在淡水環(huán)境下表達(dá)，起吸收離子作用且存在于Ⅱ型富含線粒體的細(xì)胞中[44]?？梢?，當(dāng)魚類生活于海水環(huán)境中時，其較多的是調(diào)用細(xì)胞基底膜外側(cè)的NKCC1向體外分泌離子，而當(dāng)魚類生活在淡水環(huán)境中時，較多的是調(diào)用細(xì)胞頂膜處的NKCC2和NCC向體內(nèi)吸收離子。在魚類中，關(guān)于NKCC和NCC在滲透壓調(diào)節(jié)方面已有大量文獻(xiàn)報道，但研究較多的是外界鹽度的變化對其活力及mRNA表達(dá)的影響，而食物中礦物元素對其活力的影響還需進(jìn)一步研究。

3NHE

由此可見，NHE參與Na+的吸收和H+的分泌，進(jìn)而維持體液滲透壓和酸堿平衡。但有研究指出魚類在海水環(huán)境下NHE的主要功能是維持體液的酸堿平衡[63,68-69]；而在淡水環(huán)境中，NHE的主要功能是維持體液的滲透壓平衡[58]。因而，在通過NHE途徑研究食物中礦物元素調(diào)控魚體液滲透壓平衡時，應(yīng)考慮魚體所處環(huán)境的鹽度。此外，與NKA相同，NHE也存在多種亞型，而這些亞型受外界條件的影響所產(chǎn)生的表達(dá)各不相同，因此在滲透壓平衡調(diào)節(jié)的研究中，還應(yīng)注意NHE不同亞基表達(dá)差異的影響。

4CFTR

CFTR是一種調(diào)節(jié)Cl-轉(zhuǎn)運(yùn)的陰離子通道蛋白(圖1和圖2)，主要位于硬骨魚類鰓組織中富含線粒體的泌氯細(xì)胞以及鰓蓋上皮細(xì)胞中，CFTR是通過環(huán)腺苷酸(cAMP)和蛋白激酶A(PKA)來激活的[70]。Singer等[71]對不同鹽度下的側(cè)邊底鳉體組織中CFTR基因克隆分析發(fā)現(xiàn)，當(dāng)?shù)h(huán)境中的鳉魚突然移至海水環(huán)境后，其鰓、鰓蓋上皮細(xì)胞以及腸道中CFTR基因的表達(dá)量顯著升高。Scott等[29]研究發(fā)現(xiàn)，當(dāng)鳉魚從海水環(huán)境中移至淡水環(huán)境中時，24 h內(nèi)CFTR基因的表達(dá)量顯著降低甚至消失，同樣的現(xiàn)象在羅非魚[72]中也有發(fā)現(xiàn)。魚類鰓組織的CFTR基因在海水中高表達(dá)，在淡水中低表達(dá)，說明CFTR是廣鹽性硬骨魚類鰓線粒體豐富細(xì)胞分泌Cl-，維持體內(nèi)Cl-平衡的重要調(diào)控途徑。另外，Singer等[73]對大西洋鮭的研究發(fā)現(xiàn)，CFTR也存在2種亞型，當(dāng)該魚從淡水環(huán)境中移至海水環(huán)境中2周內(nèi)，其鰓中CFTRⅠ的表達(dá)量顯著上調(diào)，而CFTRⅡ的表達(dá)量只是在最開始的24 h內(nèi)出現(xiàn)短暫的上調(diào)，說明CFTRⅡ的主要功能是應(yīng)對環(huán)境鹽度的突變。因此，在研究CFTR調(diào)控Cl-代謝而參與體液滲透壓平衡時，不僅要考慮CFTR活力，還應(yīng)考慮采樣時間和CFTR不同亞型的差異表達(dá)所帶來的影響。

5小結(jié)

根據(jù)以上研究報道，與Na+和Cl-轉(zhuǎn)運(yùn)相關(guān)的載體蛋白NKA、NKCC、NCC、NHE和CFTR均參與廣鹽性硬骨魚類的機(jī)體滲透壓調(diào)節(jié)。其中位于膜基底側(cè)的NKA主要功能是水解ATP提供能量，并將細(xì)胞中的Na+運(yùn)輸?shù)郊?xì)胞外，形成Na+濃度梯度差，進(jìn)而調(diào)節(jié)膜上NHE、NKCC、NCC調(diào)節(jié)轉(zhuǎn)運(yùn)細(xì)胞內(nèi)外環(huán)境中的Na+和Cl-。此外，位于鰓的泌氯細(xì)胞和鰓蓋上皮細(xì)胞中的CFTR主要調(diào)控Cl-的代謝，當(dāng)生活在高滲環(huán)境下，CFTR可以調(diào)節(jié)Cl-向機(jī)體外運(yùn)輸，來維持機(jī)體內(nèi)的滲透壓穩(wěn)態(tài)。目前關(guān)于魚類體液滲透壓平衡調(diào)節(jié)的研究，較多的關(guān)注水體鹽度的改變對Na和Cl轉(zhuǎn)運(yùn)載體的影響，而對于食物中礦物質(zhì)因素對滲透壓影響的研究較少。因此，通過對Na和Cl轉(zhuǎn)運(yùn)載體的功能及調(diào)控機(jī)制研究的總結(jié)，將為探討飼料礦物質(zhì)調(diào)節(jié)魚類滲透壓平衡機(jī)制提供理論依據(jù)。

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(責(zé)任編輯菅景穎)

A Review on Function and Regulatory Mechanism of Na+and Cl-Transporters in Fish

JI Zhongli1ZHANG Chunxiao2*MAI Kangsen3

(1. The Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture,Jimei University, Xiamen 361021, China; 2. Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Jimei University, Xiamen 361021, China; 3. The Key Laboratory of Mariculture,Education Ministry of China, Ocean University of China, Qingdao 266003, China)

Abstract:Not only Na+ and Cl- can participate the regulation of osmotic equilibrium and the balance of resting potential of cell membranes in fish, but the homeostasis of electrolyte in body. In the membrane of epithelial cells among gill, gastrointestinal tract and renal tubule of teleosts, there are Na+/K+-ATPase, Na+-K+-2Cl- cotransporter, Na+/H+ exchanger, cystic fibrosis transmembrane conductance regulator and the other transport proteins, those are the main control channels involving in the metabolism of Na+ and Cl-. The expression of proteins of these control channels can influence the electrolyte balance directly. This article summarized the function, factors influencing activity changes and regulatory mechanism of the main transport proteins which correlated with the transportation of Na+ and Cl-.[Chinese Journal of Animal Nutrition, 2016, 28(2)：369-378]

Key words:fish; Na+; Cl-; transporter; osmoregulation

*Corresponding author, associate professor, E-mail: cxzhang@jmu.edu.cn

中圖分類號：S917.4

文獻(xiàn)標(biāo)識碼：A

文章編號：1006-267X(2016)02-0369-10

作者簡介：吉中力(1990—)，男，福建廈門人，碩士研究生，從事水產(chǎn)動物營養(yǎng)與飼料研究。E-mail: cooljizhongli@sina.com*通信作者：張春曉，副教授，碩士生導(dǎo)師，E-mail: cxzhang@jmu.edu.cn

基金項(xiàng)目：國家自然科學(xué)基金(31001115)；福建省高校優(yōu)秀人才支持計劃(JA11145)

收稿日期：2015-08-24

doi：10.3969/j.issn.1006-267x.2016.02.009