McCollum M Q, Webb K E
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306, USA.
J Anim Sci. 1998 Oct;76(10):2706-11. doi: 10.2527/1998.76102706x.
To define the interactions between the absorption of glycyl-L-sarcosine (Gly-Sar; .1 mM) and glycine, L-methionylglycine, glycyl-L-leucine, L-carnosine, or L-methionylglycyl-L-methionyl-L-methionine (each at 5 mM), ovine omasal epithelium was collected from eight wethers (average BW=69+/-8.2 kg) and mounted in parabiotic chambers. [1,2]-[14C]Glycyl-L-sarcosine was used as a marker to monitor the presence of Gly-Sar. The Gly-Sar concentration in the omasal epithelium after 60 min of incubation was greatest (P < .05; .0055 nmol/mg dry tissue) when only Gly-Sar was present. Glycine inhibited (P < .05) Gly-Sar movement through the tissue by 20%, and peptide substrates inhibited (P < .05) Gly-Sar movement by 60 to 85%. The appearance of Gly-Sar in serosal buffers increased quadratically (P < .001) with time. Numerically, Gly-Sar appearance in serosal buffers was stimulated by the presence of glycine and peptide substrates. In a second experiment, ovine omasal epithelium was collected from four lambs (average BW=47+/-6.0 kg) to determine the interactions of Gly-Sar absorption (.1 mM) alone or when coincubated with either 10 mM butyric acid, or with a mixture of VFA (50 mM acetic acid, 40 mM propionic acid, and 10 mM butyric acid). The movement of Gly-Sar through the omasal epithelium was greatest (P < .05) when only Gly-Sar was present, and the VFA mixture inhibited (P < .05) Gly-Sar movement by 84%. Results from these studies support the idea that peptides can be absorbed across omasal epithelium and that the process involves mediated as well as nonmediated mechanisms, including possibly paracellular transport.
为了确定甘氨酰-L-肌氨酸（甘氨酰-肌氨酸；0.1 mM）与甘氨酸、L-甲硫氨酰甘氨酸、甘氨酰-L-亮氨酸、L-肌肽或L-甲硫氨酰甘氨酰-L-甲硫氨酰-L-甲硫氨酸（均为5 mM）吸收之间的相互作用，从8只阉羊（平均体重=69±8.2千克）采集绵羊瓣胃上皮，并安装在联体腔室中。[1,2]-[¹⁴C]甘氨酰-L-肌氨酸用作监测甘氨酰-肌氨酸存在的标志物。仅存在甘氨酰-肌氨酸时，孵育60分钟后瓣胃上皮中的甘氨酰-肌氨酸浓度最高（P<0.05；0.0055 nmol/mg干组织）。甘氨酸抑制（P<0.05）甘氨酰-肌氨酸通过组织的转运达20%，而肽底物抑制（P<0.05）甘氨酰-肌氨酸转运达60%至85%。甘氨酰-肌氨酸在浆膜缓冲液中的出现随时间呈二次增加（P<0.001）。从数值上看，甘氨酸和肽底物的存在刺激了甘氨酰-肌氨酸在浆膜缓冲液中的出现。在第二个实验中，从4只羔羊（平均体重=47±6.0千克）采集绵羊瓣胃上皮，以确定单独的甘氨酰-肌氨酸（0.1 mM）吸收情况，或与10 mM丁酸或挥发性脂肪酸混合物（50 mM乙酸、40 mM丙酸和10 mM丁酸）共同孵育时的吸收相互作用。仅存在甘氨酰-肌氨酸时，甘氨酰-肌氨酸通过瓣胃上皮的转运最大（P<0.05），挥发性脂肪酸混合物抑制（P<0.05）甘氨酰-肌氨酸转运达84%。这些研究结果支持以下观点：肽可以通过瓣胃上皮吸收，且该过程涉及介导和非介导机制，可能包括细胞旁转运。
