Tags

Type your tag names separated by a space and hit enter

Role of gamma-glutamyltransferase in putrescine uptake by rat type II pneumocytes.
Biochem Pharmacol. 1995 Sep 28; 50(7):981-9.BP

Abstract

Putrescine uptake in type II pneumocytes is a carrier-mediated active process. Our hypothesis was that oligoamines might be taken up into the cell at least in part by gamma-glutamyltransferase (gamma-GT). This was investigated in rat type II pneumocytes 24 hr after their isolation. Preexposure to 125 microM L-buthionine-[SR]-sulfoximine (BSO) or 100 microM diethylmaleate (DEM), both of which affect intracellular glutathione (GSH) only, were found to decrease GSH by 85% (p < 0.05) and 62%, respectively (p < 0.05), without change in [3H]-putrescine uptake. Preexposure to 20 microM N-ethylmaleimide (NEM), which affects intra- and extracellular GSH, decreased intracellular GSH by 79% (p = 0.015) and putrescine uptake by 39% (p = 0.03). Selective extracellular GSH depletion by 10 microM copper-o-phenanthroline complex (CuP) led to a decrease in putrescine uptake of 41% (p = 0.001), while intracellular GSH remained unchanged. Specific inhibition of gamma-GT by 5-20 mM serine-borate or 5 mM acivicin gave similar degrees of putrescine uptake inhibition (39.5% and 40.5%). The kinetic properties of the putrescine uptake system in the presence of acivicin and serine-borate indicated that the Vmax decreased by 25%, while Km remained unchanged. In experiments with pure gamma-GT, the oligoamines putrescine, spermidine and spermine, and cystamine proved to be acceptor substrates for gamma-GT, all having similar efficiencies (Vmax/Km); methylglyoxal-bis-(guanyl-hydrazone) and paraquat were not accepted. As extracellular GSH is required for gamma-GT, and because its extracellular depletion inhibits putrescine uptake as much as specific inhibition of gamma-GT, we suggest that 30-40% of the putrescine uptake in type II pneumocytes occurs by gamma-GT and that, therefore, at least two systems are involved in the uptake of putrescine.

Authors+Show Affiliations

Laboratory of Pneumology, K.U.Leuven, Belgium.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

7575683

Citation

van Klaveren, R J., et al. "Role of Gamma-glutamyltransferase in Putrescine Uptake By Rat Type II Pneumocytes." Biochemical Pharmacology, vol. 50, no. 7, 1995, pp. 981-9.
van Klaveren RJ, Hoet PH, Demedts M, et al. Role of gamma-glutamyltransferase in putrescine uptake by rat type II pneumocytes. Biochem Pharmacol. 1995;50(7):981-9.
van Klaveren, R. J., Hoet, P. H., Demedts, M., & Nemery, B. (1995). Role of gamma-glutamyltransferase in putrescine uptake by rat type II pneumocytes. Biochemical Pharmacology, 50(7), 981-9.
van Klaveren RJ, et al. Role of Gamma-glutamyltransferase in Putrescine Uptake By Rat Type II Pneumocytes. Biochem Pharmacol. 1995 Sep 28;50(7):981-9. PubMed PMID: 7575683.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of gamma-glutamyltransferase in putrescine uptake by rat type II pneumocytes. AU - van Klaveren,R J, AU - Hoet,P H, AU - Demedts,M, AU - Nemery,B, PY - 1995/9/28/pubmed PY - 1995/9/28/medline PY - 1995/9/28/entrez SP - 981 EP - 9 JF - Biochemical pharmacology JO - Biochem. Pharmacol. VL - 50 IS - 7 N2 - Putrescine uptake in type II pneumocytes is a carrier-mediated active process. Our hypothesis was that oligoamines might be taken up into the cell at least in part by gamma-glutamyltransferase (gamma-GT). This was investigated in rat type II pneumocytes 24 hr after their isolation. Preexposure to 125 microM L-buthionine-[SR]-sulfoximine (BSO) or 100 microM diethylmaleate (DEM), both of which affect intracellular glutathione (GSH) only, were found to decrease GSH by 85% (p < 0.05) and 62%, respectively (p < 0.05), without change in [3H]-putrescine uptake. Preexposure to 20 microM N-ethylmaleimide (NEM), which affects intra- and extracellular GSH, decreased intracellular GSH by 79% (p = 0.015) and putrescine uptake by 39% (p = 0.03). Selective extracellular GSH depletion by 10 microM copper-o-phenanthroline complex (CuP) led to a decrease in putrescine uptake of 41% (p = 0.001), while intracellular GSH remained unchanged. Specific inhibition of gamma-GT by 5-20 mM serine-borate or 5 mM acivicin gave similar degrees of putrescine uptake inhibition (39.5% and 40.5%). The kinetic properties of the putrescine uptake system in the presence of acivicin and serine-borate indicated that the Vmax decreased by 25%, while Km remained unchanged. In experiments with pure gamma-GT, the oligoamines putrescine, spermidine and spermine, and cystamine proved to be acceptor substrates for gamma-GT, all having similar efficiencies (Vmax/Km); methylglyoxal-bis-(guanyl-hydrazone) and paraquat were not accepted. As extracellular GSH is required for gamma-GT, and because its extracellular depletion inhibits putrescine uptake as much as specific inhibition of gamma-GT, we suggest that 30-40% of the putrescine uptake in type II pneumocytes occurs by gamma-GT and that, therefore, at least two systems are involved in the uptake of putrescine. SN - 0006-2952 UR - https://www.unboundmedicine.com/medline/citation/7575683/Role_of_gamma_glutamyltransferase_in_putrescine_uptake_by_rat_type_II_pneumocytes_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0006-2952(95)00223-M DB - PRIME DP - Unbound Medicine ER -