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2-Deoxy-D-glucose uptake by rat granular pneumocytes in primary culture
Abstract:
Uptake of 2-deoxy-D-glucose (DG) was investigated with rat granular pneumocytes isolated in primary culture. Cells attached to flasks were incubated in Minimal Essential Medium usually containing 5 mM DG in place of glucose. Uptake of DG increased progressively with time of incubation and approached a plateau value of 35-40 mumol/10(6) cells at 60 min. Uptake increased as a function of external DG concentration with half-maximal uptake at approximately 2.0 mM DG. DG uptake was inhibited by the presence of glucose, alpha-methylglucoside, phlorizin, ouabain, or sodium-free medium. After 60 min incubation, approximately 20% of total intracellular DG was in the free form, and the calculated mean intracellular concentration of free DG (n = 4) was approximately twice the external concentration. Phosphatase activity was indicated by increase in free DG and efflux from cells after removal of external DG. In comparison with pneumocytes, uptake of DG by alveolar macrophages showed different kinetics, and intracellular free DG did not exceed the extracellular concentration. These findings indicate that type II cells take up DG by a sodium-dependent, carrier-mediated transport process that results in accumulation of free sugar against a concentration gradient.
Insights
Rat granular pneumocytes actively transport 2-deoxy-D-glucose (DG) via a sodium-dependent carrier mechanism. This process allows cells to accumulate free DG against a concentration gradient.
Area of Science:
- Cell Biology
- Respiratory Physiology
- Biochemistry
Background:
- Type II pneumocytes are crucial alveolar cells.
- Understanding glucose uptake mechanisms in lung cells is important for respiratory health research.
Purpose of the Study:
- To investigate the uptake mechanism of 2-deoxy-D-glucose (DG) in rat type II pneumocytes.
- To characterize the kinetics and transport properties of DG uptake.
Main Methods:
- Primary culture of rat granular pneumocytes.
- Incubation with 2-deoxy-D-glucose (DG) at varying concentrations and times.
- Inhibition studies using glucose, alpha-methylglucoside, phlorizin, ouabain, and sodium-free medium.
- Comparison of DG uptake with alveolar macrophages.
Main Results:
- DG uptake increased with time and DG concentration, reaching a plateau.
- Uptake was inhibited by glucose, specific inhibitors, and sodium depletion.
- Intracellular free DG concentration exceeded extracellular levels, indicating active transport.
- Type II pneumocytes showed different DG uptake kinetics compared to alveolar macrophages.
Conclusions:
- Rat type II pneumocytes utilize a sodium-dependent, carrier-mediated transport system for DG uptake.
- This process facilitates the accumulation of free DG against a concentration gradient.
- The findings provide insights into glucose transport in lung alveolar cells.