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J Biol Chem. 2011 Jan 14;286(2):1054-60. doi: 10.1074/jbc.M110.176552. Epub 2010 Nov 12.

Diminished paracrine regulation of the epithelial Na+ channel by purinergic signaling in mice lacking connexin 30.

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1
Department of Physiology, University of Texas Health Science Center, San Antonia, Texas 78229-3900, USA.

Abstract

We tested whether ATP release through Connexin 30 (Cx30) is part of a local purinergic regulatory system intrinsic to the aldosterone-sensitive distal nephron (ASDN) important for proper control of sodium excretion; if changes in sodium intake influence ATP release via Cx30; and if this allows a normal ENaC response to changes in systemic sodium levels. In addition, we define the consequences of disrupting ATP regulation of ENaC in Cx30(-/-) mice. Urinary ATP levels in wild-type mice increase with sodium intake, being lower and less dependent on sodium intake in Cx30(-/-) mice. Loss of inhibitory ATP regulation causes ENaC activity to be greater in Cx30(-/-) versus wild-type mice, particularly with high sodium intake. This results from compromised ATP release rather than end-organ resistance: ENaC in Cx30(-/-) mice responds to exogenous ATP. Thus, loss of paracrine ATP feedback regulation of ENaC in Cx30(-/-) mice disrupts normal responses to changes in sodium intake. Consequently, ENaC is hyperactive in Cx30(-/-) mice lowering sodium excretion particularly during increases in sodium intake. Clamping mineralocorticoids high in Cx30(-/-) mice fed a high sodium diet causes a marked decline in renal sodium excretion. This is not the case in wild-type mice, which are capable of undergoing aldosterone-escape. This loss of the ability of ENaC to respond to changes in sodium levels contributes to salt-sensitive hypertension in Cx30(-/-) mice.

PMID:
21075848
PMCID:
PMC3020712
DOI:
10.1074/jbc.M110.176552
[Indexed for MEDLINE]
Free PMC Article
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