Significance of gamma-glutamyltranspeptidase in exocrine pancreatic amino acid transport.
The exocrine pancreas is rich in gamma-glutamyltranspeptidase (GGT, EC 2.3.2.2) and exhibits high rates of amino acid transport and protein synthesis. The role of the gamma-glutamyl cycle in mediating neutral amino acid transport in the isolated perfused rat pancreas was investigated using acivicin, an inhibitor of GGT, and a rapid dual isotope dilution technique. When treatment in vivo with acivicin (50 mg/kg) was followed 1 h later by continuous perfusion of the isolated pancreas with 10 microM acivicin, GGT levels decreased from 53 +/- 3 IU/g to 4.9 +/- 1.5 IU/g. This marked inhibition of GGT activity was not associated with decreased uptake for either L-alanine or L-glutamine, suggesting that the gamma-glutamyl cycle plays a negligible role in amino acid transport across the basolateral membrane of the pancreatic epithelium.
Sastre
J
J
Biomedical Sciences Division, King's College London, U.K.
Sweiry
J H
JH
Doolabh
K
K
Viña
J
J
Mann
G E
GE
D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D004848:Epithelium / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D007201:Indicator Dilution Techniques; D007555:Isoxazoles / Q000494:pharmacology; D008297:Male; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000596:Amino Acids; D007555:Isoxazoles; D005973:Glutamine; D005723:gamma-Glutamyltransferase; C006303:acivicin; D000409:Alanine