Amino acid transport is down-regulated in ischemic human intestinal epithelial cells.
Amino acid transport across the plasma membrane is essential for supplying enterocytes with amino acids for cellular metabolism. We studied amino acid transport during ischemic conditions using human intestinal epithelial cell line Caco-2. Cells were incubated under nutrient-deprived (phosphate-buffered saline, PBS), hypoxic, and ischemic (PBS+hypoxia) conditions. Ischemia resulted in a significant decrease in glutamine transport by a mechanism that decreased V(max) without affecting K(m). The expression of system ATB degrees (glutamine transporter) mRNA decreased in the ischemic and nutrient-deprived groups, suggesting that the down-regulation of glutamine transport is due to modification of expression of the ATB degrees gene. The transport of glutamate and leucine, DNA synthesis, and intracellular glutathione also decreased in the ischemic group. These findings throw some light on the mechanism of intestinal epithelial damage during ischemia.
Wasa
Masafumi
M
Department of Pediatric Surgery, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. wasa@pedsurg.med.osaka-u.ac.jp
Wang
Hong-Sheng
HS
Shimizu
Yoshiyuki
Y
Okada
Akira
A
D026962:Amino Acid Transport System ASC / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport; D018938:Caco-2 Cells; D004247:DNA / Q000096:biosynthesis; D004847:Epithelial Cells / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D005978:Glutathione / Q000096:biosynthesis; D006801:Humans; D007422:Intestines / Q000098:blood supply*; D007511:Ischemia / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D015778:Minor Histocompatibility Antigens; D013997:Time Factors
D026962:Amino Acid Transport System ASC; D000596:Amino Acids; D015778:Minor Histocompatibility Antigens; C420506:SLC1A5 protein, human; D005973:Glutamine; D004247:DNA; D005978:Glutathione; D007930:Leucine