离体草鱼肠道对亮氨酸和酪氨酸的吸收与利用

采用同位素示踪和肠道离体灌流方法,研究了草鱼离体肠道对亮氨酸(Leu)、酪氨酸(Tyr)的吸收转运与利用。实验结果表明:当Leu浓度从1.0mmol/L增加到5.0mmol/L、10mmol/L时,肠道吸收转运的速度表现出“高浓度抑制”效应,运输到肠道外的比例为83%、66%和35%;合成肠道蛋白质的比例为2%、5%和13%;肠道组织内游离形式的比例为9%、28%和49%;其他形式的比例为6%、1%和3%。Tyr浓度从0.5mmol/L增加到1.5mmol/L、2.5mmol/L时,肠道对Tyr的吸收转运速度也随之增加,运输到肠道外的比例为52%、55%和55%;合成肠道蛋白质的比例为17%、15%和16%:肠道组织内游离形式的比例为7%、10%和16%;其他形式的比例为24%、20%和13%。肠道在吸收转运Leu和Tyr的同时,也利用它们合成蛋白质的和其他方面,Leu的吸收利用受灌流试验氨基酸浓度影响较大、而Tyr受影响较小;随着肠道内灌流的试验氨基酸浓度增加,吸收转运到肠道外的比例下降、留存于肠道内的比例增加,肠道合成的蛋白质绝对量也增加。  

STUDY ON THE ABSORPTION AND UTILIZATION OF L-LEUCINE AND L-TYROSINE BY THE INTESTINE OF GRASS CARP( CTENOPHARYNGODON IDELLUS )IN VITRO

The transmural fluxes of L-Leucine and L-Tyrosine were measured by in the intestinal gut, using the in vitro perfusiontechnique. The transmural rates of L-Leucine are01026, 01062 and 01038 (L mol/g/min)when the concentrations of the perfusionLeucine are 110, 510 and 1010mmol/L at the 10 min respectively. The transmural rates of L-Tyrosine are 01006, 01024 and01039 (Lmol/g/min) when the concentrations of the perfusion L-Tyrosine are 015, 115 and 215mmol/L the 10min respective-ly1The total absorption ratios of the L-Leucine are 12.83%, 18.85% and 16.45% when the concentrations of the perfusionL-Leucine are 110, 510 and 1010mmol/L for 40 minutes respectively. The total absorption ratios of the L-Tyrosine are 22.18%,23.68% and 27.49% when the concentrations of the perfusion L-Tyrosine are 0.5,1.5 and 2.5mmol/L for 40 minutes respec-tively.The percentage of the transmural fluxes through the intestinal gut, the free in intestine, that in new synthesized protein andthe remainders in intestine to the total absorbed amino acid were calculated respectively. When the concentration of the perfusionL-Leucine are changed from 1.0mmol/L to 5.0mmol/L and 10.0mmol/L, the transmural ratio are 83%,66% and 35% respec-tively. The free in intestine are 9%,28% and 49% respectively. That in protein are 2%, 5% and 13%. The remainders are6%,1% and 3% respectively. When the concentration of the perfusion L-Tyrosine are changed from 0.5mmol/L to 1.5mmol/Land 2.5mmol/L, the transmural ratio are 52%, 55% and 55% respectively. The free in intestine are 7%, 10% and 16% re-spectively. That in protein are 17%, 15% and 16%. The remainders are 24%, 20% and 13% respectively.