1. Kidney and Colon Electrolyte Transport in CHIF Knockout Mice
- Author
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Goldschmidt, I., Grahammer, F., Warth, R., Schulz-Baldes, A., Garty, H., Greger, R., Bleich, M., and Rid, Annette
- Subjects
medicine.medical_specialty ,Physiology ,medicine.drug_class ,Colon ,Kidney ,chemistry.chemical_compound ,Electrolytes ,Mice ,Internal medicine ,medicine ,Animals ,Ion transporter ,Mice, Knockout ,Aldosterone ,Ion Transport ,Water Deprivation ,Sodium ,Membrane Proteins ,Transmembrane protein ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Membrane protein ,Knockout mouse ,Potassium ,Corticosteroid ,Sodium-Potassium-Exchanging ATPase ,Hormone - Abstract
Corticosteroid hormone induced factor (CHIF) is a small epithelial-specific protein regulated by aldosterone and K+ intake. It is a member of the FXYD family of single span transmembrane proteins involved in the regulation of ion transport. Recent data have suggested that CHIF interacts with the a subunit of the Na+-K+-ATPase and increases the pump's affinity to cell Na+. CHIF knockout (KO) mice have mild renal phenotype under low Na+ or high K+ diets. The present study further characterizes kidney electrolyte metabolism in CHIF KO mice and describes abnormalities in the colonic ion transport function. Kidney: KO mice were not compromised in salt and water balance under resting conditions. Fractional excretions (FE) of Na+ and K+ were normal and the animals had no deficit in the adaptation to low Na+ or high K+ intake. Glucocorticoid treatment did not unmask any difference. The effects of amiloride on Na+ absorption were not different at any treatment protocol. In contrast, FEK+ was reduced by 35% in KO mice under low Na+ intake. COLON: Amiloride inhibitable Na+ absorption was reduced in distal colon by 42%, 54% and 58% under control conditions, glucocorticoid treatment and low Na+ intake, respectively. Also, the cAMP dependent ion transport was significantly diminished. Forskolin induced equivalent short circuit current (I'SC) was reduced by 41%, 32% and 58%, under control conditions, high K+, and low Na+ intake, respectively. The present findings support a role of CHIF as an indirect modulator of several different ion transport mechanisms and are consistent with regulation of the Na+-K+-ATPase as the common denominator.
- Published
- 2004