鲤肠道对L-甲硫氨酸和L-苯丙氨酸的离体吸收动力学  

Absorption kinetics of L-methionine and L-phenylalanine in isolated intestine of common carp(Cyprinus carpio)

作　　者：向枭[1] 周兴华[1] 叶元土[2] 陈建[1] 段彪[1] 

机构地区：[1]西南大学荣昌校区水产系,重庆荣昌402460 [2]苏州大学生命科学学院,江苏苏州215123

出　　处：《水产学报》2009年第2期271-277,共7页Journal of Fisheries of China

基　　金：重庆市科委攻关项目资助(97-4767)

摘　　要：采用离体灌注试验系统和茚三酮对氨基酸显色的试验方法,定量分析了鲤肠道壁对氨基酸吸收和跨壁运输量,在相同的试验环境下,分别研究鲤肠道对L-甲硫氨酸和L-苯丙氨酸的吸收转运量。结果表明,在60 min内鲤肠道可对灌流液的氨基酸进行持续的吸收转运,并在肠道外积累;当肠道内灌流氨基酸浓度逐渐增加时,肠道外培养液中氨基酸的浓度与其起始浓度呈正相关变化,并未出现高浓度氨基酸对吸收转运的"抑制"效应;通过对吸收转运量达到最大值时试验氨基酸的浓度与吸收转运量的比较,以及氨基酸吸收转运量随时间的变化规律等的比较分析表明,鲤肠道能有效地吸收、运输L-甲硫氨酸和L-苯丙氨酸。鲤肠道对L-甲硫氨酸和L-苯丙氨酸的吸收曲线符合Michaelis-Menten方程。两种氨基酸的吸收动力学方程分别为:1/V=0.125 1×1/[S]+0.052 4(R2=0.978 1,P<0.05)和1/V=0.188 7×1/[S]+0.028 8(R2=0.976 2,P<0.05),动力学参数为:L-甲硫氨酸:Vmax=19.08μmol/(g.min),Kmax=2.39 mmol/L;L-苯丙氨酸:Vmax=34.72μmol/(g.min),Kmax=6.55 mmol/L。吸收动力学特征分析表明:鲤肠道对两种氨基酸的吸收是一种逆浓度、需要转运载体的主动吸收方式,且对不同的氨基酸有不同的吸收、运输特异性,鲤肠道对L-甲硫氨酸的吸收率和跨壁运输能力均强于L-苯丙氨酸(P<0.05)。The experiment methods were used to determine the absorption and transportion of L-methionine and L-phenylalanine in isolated intestine. The method simulates the physiological condition in vitro. According to the change of amino acid solutions and outside the intestine that was controlled flowing through the intestine. We detemined the L-methionine and L-phenylalanine absorbed and transported across the intestine mural directly. In the experiment, the fingerling Cyprinus carpio were employed and after 24 h starvation the intestine was obtained and cultured in vitro. The concentration levels of L-methionine and L- phenylalanine were designed at 2.5 mmol/L,5.0 mmol/L,7.5 mmol/L and 10.0 mmol/L respectively. In each solution, the penicillin was added at 0.09 mg/mL, at the same time, sulfate streptomycin was added at 0.15 mg/mL. The absorbing capacity of L-methionine and L-phenylalanine in the intestine was analyse within 21 min, the concentrations of the L-methionine and L-phenylalanine in the exudation outside the intestine mural was analysed within 60 min. The result showed that the intestine of common carp could absorb and transport effectively. The mucosal influx of both L-methionine and L-phenylalanine occurred via a carrier-mediated. Active transportation entry process showed Michaelis-Menten kinetics. The absorption kinetic equations of L-methionine and L-phenylalanine were 1/V = 0. 1251 ×1/[S ] ＋ 0. 0524 （ R2 = 0. 978 1, P 〈0. 05）and 1/V=0. 1887×1/[S] ＋0. 0288（R^2 =0. 976 2,P 〈0. 05）, respectively; At the same time, the kinetic constants of L-methionine and L-phenylalanine were Vmax = 19.08μmol/（ g . min）, Kmax = 2.39 mmol/L; Vmax = 34. 72μmol/（ g . min ）, Kmax = 6. 55 mmoL/L, respectively. The absorption kinetics characteristic analysis indicated that the mucosal influx and the transmural of L-methionine were higher than those of L-phenylalanine （ P 〈 0.05 ）.

关 键 词：鲤 L-甲硫氨酸 L-苯丙氨酸 吸收动力学 肠道 

分 类 号：S963.162[农业科学—水产养殖]