| First Author | Wu P | Year | 2019 |
| Journal | J Am Soc Nephrol | Volume | 30 |
| Issue | 2 | Pages | 216-227 |
| PubMed ID | 30559144 | Mgi Jnum | J:290704 |
| Mgi Id | MGI:6436246 | Doi | 10.1681/ASN.2018080799 |
| Citation | Wu P, et al. (2019) Kir4.1/Kir5.1 Activity Is Essential for Dietary Sodium Intake-Induced Modulation of Na-Cl Cotransporter. J Am Soc Nephrol 30(2):216-227 |
| abstractText | BACKGROUND: Dietary sodium intake regulates the thiazide-sensitive Na-Cl cotransporter (NCC) in the distal convoluted tubule (DCT). Whether the basolateral, inwardly rectifying potassium channel Kir4.1/Kir5.1 (a heterotetramer of Kir4.1/Kir5.1) in the DCT is essential for mediating the effect of dietary sodium intake on NCC activity is unknown. METHODS: We used electrophysiology, renal clearance techniques, and immunoblotting to examine effects of Kir4.1/Kir5.1 in the DCT and NCC in wild-type and kidney-specific Kir4.1 knockout mice. RESULTS: Low sodium intake stimulated basolateral Kir4.1/Kir5.1 activity, increased basolateral K(+) conductance, and hyperpolarized the membrane. Conversely, high sodium intake inhibited the potassium channel, decreased basolateral K(+) currents, and depolarized the membrane. Low sodium intake increased total and phosphorylated NCC expression and augmented hydrochlorothiazide-induced natriuresis; high sodium intake had opposite effects. Thus, elevated NCC activity induced by low sodium intake was associated with upregulation of Kir4.1/Kir5.1 activity in the DCT, whereas inhibition of NCC activity by high sodium intake was associated with diminished Kir4.1/Kir5.1 activity. In contrast, dietary sodium intake did not affect NCC activity in knockout mice. Further, Kir4.1 deletion not only abolished basolateral K(+) conductance and depolarized the DCT membrane, but also abrogated the stimulating effects induced by low sodium intake on basolateral K(+) conductance and hyperpolarization. Finally, dietary sodium intake did not alter urinary potassium excretion rate in hypokalemic knockout and wild-type mice. CONCLUSIONS: Stimulation of Kir4.1/Kir5.1 by low intake of dietary sodium is essential for NCC upregulation, and inhibition of Kir4.1/Kir5.1 induced by high sodium intake is a key step for downregulation of NCC. |
