Potassium secretion by voltage-gated potassium channel Kv1.3 in the rat kidney

作者：Carrisoza Gaytan Rolando; Salvador Carolina; Satlin Lisa M; Liu Wen; Zavilowitz Beth; Bobadilla Norma A; Trujillo Joyce; Escobar Laura I^*

来源：American Journal of Physiology - Renal Fluid and Electrolyte Physiology, 2010, 299(1): F255-F264.

DOI：10.1152/ajprenal.00697.2009

• potassium diet
• potassium transport
• distal nephron
• intercalated cell
• rat kidney
• urine pH

Carrisoza-Gaytan R, Salvador C, Satlin LM, Liu W, Zavilowitz B, Bobadilla NA, Trujillo J, Escobar LI. Potassium secretion by voltage-gated potassium channel Kv1.3 in the rat kidney. Am J Physiol Renal Physiol 299: F255-F264, 2010. First published April 28, 2010; doi: 10.1152/ajprenal.00697.2009.-The fine regulation of Na(+) and K(+) transport takes place in the cortical distal nephron. It is well established that K(+) secretion occurs through apical K(+) channels: the ROMK and the Ca2(+)- and voltage-dependent maxi-K. Previously, we identified the voltage-gated Kv1.3 channel in the inner medulla of the rat kidney (Escobar LI, Martinez-Tellez JC, Salas M, Castilla SA, Carrisoza R, Tapia D, Vazquez M, Bargas J, Bolivar JJ. Am J Physiol Cell Physiol 286: C965-C974, 2004). To examine the role of Kv1.3 in the renal regulation of K(+) homeostasis, we characterized the effect of dietary K(+) on the molecular and functional expression of this channel. We performed real-time-PCR and immunoblot assays in kidneys from rats fed a control (CK; 1.2% wt/wt) or high-K(+) (HK; 10% wt/wt) diet for 5-15 days. Kv1.3 mRNA and protein expression did not change with HK in the whole kidney. However, dietary K(+) loading provoked a change in the cellular distribution of Kv1.3 from the cytoplasm to apical membranes. Immunolocalization of Kv1.3 detected the channel exclusively in the intercalated cells. We investigated whether Kv1.3 mediated K(+) transport in microperfused cortical collecting ducts (CCDs). The HK diet led to an increase in net K(+) transport from 7.4 +/- 1.1 (CK) to 11.4 +/- 1.0 (HK) pmol.min(-1).mm(-1). Luminal margatoxin, a specific blocker of Kv1.3, decreased net K(+) secretion in HK CCDs to 6.0 +/- 1.6 pmol.min(-1).mm(-1). Our data provide the first evidence that Kv1.3 channels participate in K(+) secretion and that apical membrane localization of Kv1.3 is enhanced in the intercalated cells by dietary K(+) loading.

• 出版日期2010-7