Spermidine uptake by type II pneumocytes: Interactions of amine uptake pathways

D. E. Rannels, R. Kameji, Anthony Pegg, S. R. Rannels

Research output: Contribution to journalArticle

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Abstract

Uptake of exogenous spermidine by type II pulmonary epithelial cells in primary culture is inhibited by several amines. The present studies further detail the interaction of those alternative substrates with the pathway for spermidine (SPD) transport. Transport activity was measured on the first day of primary culture in type II cells isolated by elastase digestion, followed by density gradient centrifugation and differential adherence in vitro. Spermidine uptake was inhibited in a concentration-dependent manner by the polyamine putrescine (PUTR) and spermine (SPM), by the drug methylglyoxal bis-(guanylhydrazone) (MGBG), and by the herbicide paraquat (PQ). The order of effectiveness of these competitors was SPM > PUTR ≃ MGBG >> PQ. The kinetics of inhibition by SPM were mixed, with an increase in the apparent Michaelis constant and a reduction in the maximal velocity of the SPD uptake pathway. Cellular uptake of SPD and PUTR was inhibited by replacement of extracellular sodium with choline or lithium (PUTR > SPD), but SPM uptake was unaffected. PQ appeared to interact with the polyamine transport pathway with low affinity. Compared with SPD and SPM, PQ was most effective as an inhibitor of PUTR uptake, and like PUTR, uptake of the herbicide was sharply inhibited as extracellular sodium was reduced. These observations suggest the presence of diverse pathways for uptake of exogenous polyamines by type II pulmonary epithelial cells and indicate that PQ probably enters the cells by the sodium-dependent transport system favored by PUTR.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume257
Issue number6
StatePublished - Dec 1 1989

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Alveolar Epithelial Cells
Putrescine
Spermidine
Amines
Paraquat
Spermine
Polyamines
Mitoguazone
Sodium
Herbicides
Epithelial Cells
Lung
Density Gradient Centrifugation
Pancreatic Elastase
Choline
Lithium
Pharmaceutical Preparations
Digestion

All Science Journal Classification (ASJC) codes

  • Cell Biology
  • Physiology
  • Pulmonary and Respiratory Medicine

Cite this

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abstract = "Uptake of exogenous spermidine by type II pulmonary epithelial cells in primary culture is inhibited by several amines. The present studies further detail the interaction of those alternative substrates with the pathway for spermidine (SPD) transport. Transport activity was measured on the first day of primary culture in type II cells isolated by elastase digestion, followed by density gradient centrifugation and differential adherence in vitro. Spermidine uptake was inhibited in a concentration-dependent manner by the polyamine putrescine (PUTR) and spermine (SPM), by the drug methylglyoxal bis-(guanylhydrazone) (MGBG), and by the herbicide paraquat (PQ). The order of effectiveness of these competitors was SPM > PUTR ≃ MGBG >> PQ. The kinetics of inhibition by SPM were mixed, with an increase in the apparent Michaelis constant and a reduction in the maximal velocity of the SPD uptake pathway. Cellular uptake of SPD and PUTR was inhibited by replacement of extracellular sodium with choline or lithium (PUTR > SPD), but SPM uptake was unaffected. PQ appeared to interact with the polyamine transport pathway with low affinity. Compared with SPD and SPM, PQ was most effective as an inhibitor of PUTR uptake, and like PUTR, uptake of the herbicide was sharply inhibited as extracellular sodium was reduced. These observations suggest the presence of diverse pathways for uptake of exogenous polyamines by type II pulmonary epithelial cells and indicate that PQ probably enters the cells by the sodium-dependent transport system favored by PUTR.",
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Spermidine uptake by type II pneumocytes : Interactions of amine uptake pathways. / Rannels, D. E.; Kameji, R.; Pegg, Anthony; Rannels, S. R.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 257, No. 6, 01.12.1989.

Research output: Contribution to journalArticle

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T1 - Spermidine uptake by type II pneumocytes

T2 - Interactions of amine uptake pathways

AU - Rannels, D. E.

AU - Kameji, R.

AU - Pegg, Anthony

AU - Rannels, S. R.

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N2 - Uptake of exogenous spermidine by type II pulmonary epithelial cells in primary culture is inhibited by several amines. The present studies further detail the interaction of those alternative substrates with the pathway for spermidine (SPD) transport. Transport activity was measured on the first day of primary culture in type II cells isolated by elastase digestion, followed by density gradient centrifugation and differential adherence in vitro. Spermidine uptake was inhibited in a concentration-dependent manner by the polyamine putrescine (PUTR) and spermine (SPM), by the drug methylglyoxal bis-(guanylhydrazone) (MGBG), and by the herbicide paraquat (PQ). The order of effectiveness of these competitors was SPM > PUTR ≃ MGBG >> PQ. The kinetics of inhibition by SPM were mixed, with an increase in the apparent Michaelis constant and a reduction in the maximal velocity of the SPD uptake pathway. Cellular uptake of SPD and PUTR was inhibited by replacement of extracellular sodium with choline or lithium (PUTR > SPD), but SPM uptake was unaffected. PQ appeared to interact with the polyamine transport pathway with low affinity. Compared with SPD and SPM, PQ was most effective as an inhibitor of PUTR uptake, and like PUTR, uptake of the herbicide was sharply inhibited as extracellular sodium was reduced. These observations suggest the presence of diverse pathways for uptake of exogenous polyamines by type II pulmonary epithelial cells and indicate that PQ probably enters the cells by the sodium-dependent transport system favored by PUTR.

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