Characterization of the thiazide-sensitive Na(+)-Cl(-) cotransporter: a new model for ions and diuretics interaction.

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Monroy A, Plata C, Hebert SC, Gamba G

Characterization of the thiazide-sensitive Na(+)-Cl(-) cotransporter: a new model for ions and diuretics interaction.

Am J Physiol Renal Physiol. 2000 Jul;279(1):F161-9.

PubMed ID

10894798 [ View in PubMed

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Abstract

The thiazide-sensitive Na(+)-Cl(-) cotransporter (TSC) is the major pathway for salt reabsorption in the apical membrane of the mammalian distal convoluted tubule. When expressed in Xenopus laevis oocytes, rat TSC exhibits high affinity for both cotransported ions, with the Michaelis-Menten constant (K(m)) for Na(+) of 7.6 +/- 1.6 mM and for Cl(-) of 6.3 +/- 1.1 mM, and Hill coefficients for Na(+) and Cl(-) consistent with electroneutrality. The affinities of both Na(+) and Cl(-) were increased by increasing concentration of the counterion. The IC(50) values for thiazides were affected by both extracellular Na(+) and Cl(-). The higher the Na(+) or Cl(-) concentration, the lower the inhibitory effect of thiazides. Finally, rTSC function is affected by extracellular osmolarity. We propose a transport model featuring a random order of binding in which the binding of each ion facilitates the binding of the counterion. Both ion binding sites alter thiazide-mediated inhibition of transport, indicating that the thiazide-binding site is either shared or modified by both Na(+) and Cl(-).

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Bendroflumethiazide	Solute carrier family 12 member 3	Protein	Humans	Yes	Inhibitor	Details
Hydrochlorothiazide	Solute carrier family 12 member 3	Protein	Humans	Yes	Inhibitor	Details
Polythiazide	Solute carrier family 12 member 3	Protein	Humans	Yes	Inhibitor	Details