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Tetraethylammonium transport by OK cells
T D McKinney1, M B Scheller, M Hosford
1Medical Service, Veterans Administration Medical Center, Indianapolis, IN.
Journal of the American Society of Nephrology : JASN
|December 1, 1990
Summary
Opossum kidney cells exhibit mediated uptake of organic cations like tetraethylammonium (TEA), suggesting they are a valuable in vitro model for studying renal transport mechanisms.
Area of Science:
- Nephrology
- Cell Biology
- Biochemistry
Background:
- Renal proximal tubules actively transport organic cations.
- Understanding these transport mechanisms is crucial for drug disposition and toxin elimination.
Purpose of the Study:
- To investigate the utility of opossum kidney (OK) cells as an in vitro model for renal organic cation transport.
- To characterize the uptake kinetics and identify potential transport systems for organic cations in OK cells.
Main Methods:
- Uptake of radiolabeled tetraethylammonium (³H-TEA) into confluent OK cell monolayers was measured.
- Inhibition studies were performed using various organic cations and ionophores.
- The effect of pH and metabolic inhibitors on TEA uptake was assessed.
Main Results:
- ³H-TEA uptake was time-dependent, saturable (Km = 59.1 µM), and energy-dependent (inhibited by sodium azide).
- Uptake was significantly inhibited by amiloride, cimetidine, verapamil, procainamide, and quinidine, but not N'-methylnicotinamide.
- Alkaline pH enhanced uptake, but it was independent of cellular pH and bicarbonate, ruling out proton exchange.
Conclusions:
- OK cells possess a mediated transport system for organic cation uptake.
- These cells represent a suitable in vitro model for studying renal epithelial transport of organic cations.
- The transport mechanism does not appear to involve organic cation/proton or organic cation/organic cation exchange.