A voltage-gated K+ current in renal inner medullary collecting duct cells
Por:
Escobar L.I., Martínez-Téllez J.C., Salas M., Castilla S.A., Carrisoza R., Tapia D., Vázquez M., Bargas J., Bolívar J.J.
Publicada:
1 ene 2004
Resumen:
We studied the K+-selective conductances in primary cultures of rat renal inner medullary collecting duct (IMCD) using perforated-patch and conventional whole cell techniques. Depolarizations above -20 mV induced a time-dependent outward K+ current (Ivto) similar to a delayed rectifier. Ivto showed a half-maximal activation around 5.6 mV with a slope factor of 6.8 mV. Its K+/Na+ selectivity ratio was 11.7. It was inhibited by tetraethyl-ammonium, quinidine, 4-aminopyridine, and Ba2+ and was not Ca2+ dependent. The delayed rectifying characteristics of Ivto prompted us to screen the expression of Kv1 and Kv3 families by RT-PCR. Analysis of RNA isolated from cell cultures revealed the presence of three Kv ?-subunits (Kv1.1, Kv1.3, and Kv1.6). Western blot analysis with Kv ?-subunit antibodies for Kv1.1 and Kv1.3 showed labeling of ?70-kDa proteins from inner medulla plasmatic and microsome membranes. Immunocytochemical analysis of cell culture and kidney inner medulla showed that Kv1.3 is colocalized with the Na+-K +-ATPase at the basolateral membrane, although it is also in the cytoplasm. This is the first evidence of recording, protein expression, and localization of a voltage-gated Kv1 in the kidney IMCD cells.
Filiaciones:
Escobar L.I.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Martínez-Téllez J.C.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Salas M.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Castilla S.A.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Carrisoza R.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Tapia D.:
Departamento de Biofísica, Instituto de Fisiologia Celular, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Vázquez M.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Bargas J.:
Departamento de Biofísica, Instituto de Fisiologia Celular, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Bolívar J.J.:
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, Mexico City DF, 04510, Mexico
Departamento de Fisiología, Facultad de Medicina, Univ. Nacional Autonoma de Mexico, PO Box 70-250, México City DF, 04510, Mexico
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