Wang HP |
------>authors3_c= ------>paper_class1=1 ------>Impact_Factor=None ------>paper_class3=1 ------>paper_class2=1 ------>vol=47 ------>confirm_bywho=amel ------>insert_bywho=hpw ------>Jurnal_Rank=None ------>authors4_c= ------>comm_author= ------>patent_EDate=None ------>authors5_c= ------>publish_day=1 ------>paper_class2Letter=None ------>page2=35 ------>medlineContent= ------>unit=G0100 ------>insert_date=20080321 ------>iam=1 ------>update_date=None ------>author=??? ------>change_event=4 ------>ISSN= ------>authors_c= ------>score=52 ------>journal_name=Chin. Pharm. J. ------>paper_name=Studies on the Uptake of Dipeptides in Brush Border Membrane Vesicle from Rat Intestine. ------>confirm_date=20080506 ------>tch_id=096021 ------>pmid=8391693 ------>page1=23 ------>fullAbstract=The mechanism of thyrotropin-releasing hormone (pGlu-His-Pro-NH2; TRH) uptake across the luminal membrane of intestinal enterocytes was investigated using brush-border membrane vesicles (BBMV) from rabbit duodenum and jejunum and rat upper small intestine. [14C]Glucose accumulated within the intestinal vesicles (at 10 sec), in the presence of an inwardly directed Na+ gradient, 7- to 14-fold higher than equilibrium values (65 min). The vesicles also accumulated the dipeptide [14C]Gly-Sar. Dipeptide uptake was greatest in the presence of both an inwardly directed proton gradient and an inside negative membrane potential. The H(+)-dependent Gly-Sar transport was not affected by the presence of an excess (46-fold) of cold TRH. In contrast to the observations with glucose and Gly-Sar, the uptake of [3H]TRH after 10 or 60 sec (in each of the vesicle preparations) was not enhanced by either Na+ or H+ gradient conditions. The absence of vesicular accumulation of TRH was not due to peptide hydrolysis. For example, after a 60-sec incubation with rabbit jejunal BBMV no degradation of the tripeptide was evident. After 65 min, 6% of [3H]TRH had undergone degradation, by deamidation, to form TRH-OH. These studies provide no evidence for the oral absorption of TRH by a Na(+)- or H(+)-dependent carrier system in the brush-border membrane. Previous observations of TRH absorption in vivo may be accounted for by passive absorption of the peptide combined with its relative resistance to luminal hydrolysis. ------>tmu_sno=None ------>sno=17078 ------>authors2=Huang JD ------>authors3=Cheng CY ------>authors4=Bair CH ------>authors5=LeeJS ------>authors6=CheePJ ------>authors6_c= ------>authors=Wang HP ------>delete_flag=0 ------>SCI_JNo=None ------>authors2_c= ------>publish_area=0 ------>updateTitle=Thyrotropin-releasing hormone (TRH) uptake in intestinal brush-border membrane vesicles: comparison with proton-coupled dipeptide and Na(+)-coupled glucose transport. ------>language=2 ------>check_flag=None ------>submit_date=None ------>country=None ------>no= ------>patent_SDate=None ------>update_bywho=None ------>publish_year=1995 ------>submit_flag=None ------>publish_month=1 |