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Rat NKCC2/NKCC1 cotransporter selectivity for loop diuretic drugs.
P Hannaert1, M Alvarez-Guerra, D Pirot
1INSERM U400, Faculté de Médecine, 8 rue du Général Sarrail, 94010 Créteil Cédex, France.
Naunyn-Schmiedeberg'S Archives of Pharmacology
|March 8, 2002
Summary
Loop diuretics like bumetanide lack selectivity between renal NKCC2 and activated non-renal NKCC1 transporters. Basal NKCC1 shows reduced sensitivity to these drugs, varying by drug and cell type.
Area of Science:
- Pharmacology
- Nephrology
- Molecular Biology
Background:
- Loop diuretics are assumed to selectively target the renal Na-K-Cl cotransporter (NKCC2).
- Previous comparisons of diuretic selectivity involved the non-renal NKCC1 transporter in a minimally active state.
- The influence of NKCC1 activation state on loop diuretic selectivity remains underexplored.
Purpose of the Study:
- To investigate the NKCC2/NKCC1 selectivity of bumetanide, piretanide, and furosemide.
- To assess selectivity as a function of NKCC1 activation state.
- To compare diuretic potency against activated NKCC1 and basal NKCC1.
Main Methods:
- NKCC2 activity measured in isolated rat medullary thick ascending limb (mTAL).
- NKCC1 activity measured in rat thymocytes and erythrocytes, both in basal and activated (hypertonic media) states.
- Molecular modeling to predict drug-target interactions.
Main Results:
- All three loop diuretics inhibited both NKCC2 and activated NKCC1 with similar potency.
- Basal NKCC1 exhibited reduced diuretic sensitivity, with variations depending on the specific drug and cell type.
- Molecular modeling suggested structural reasons for differential binding to basal NKCC1.
Conclusions:
- Loop diuretics do not exhibit NKCC2/NKCC1 selectivity when NKCC1 is in its activated state.
- Basal NKCC1 displays a diminished sensitivity to loop diuretics, with cell-type and drug-specific differences.
- Drug structure, particularly lipophilicity and specific binding groups, influences interaction with basal NKCC1.