Activation of the epithelial Na+ channel in the collecting duct by vasopressin contributes to water reabsorption.
We used patch-clamp electrophysiology on isolated, split-open murine collecting ducts (CD) to test the hypothesis that regulation of epithelial sodium channel (ENaC) activity is a physiologically important effect of vasopressin. Surprisingly, this has not been tested directly before. We ask whether vasopressin affects ENaC activity distinguishing between acute and chronic effects, as well as, parsing the cellular signaling pathway and molecular mechanism of regulation. In addition, we quantified possible synergistic regulation of ENaC by vasopressin and aldosterone associating this with a requirement for distal nephron Na+ reabsorption during water conservation vs. maintenance of Na+ balance. We find that vasopressin significantly increases ENaC activity within 2-3 min by increasing open probability (P(o)). This activation was dependent on adenylyl cyclase (AC) and PKA. Water restriction (18-24 h) and pretreatment of isolated CD with vasopressin (approximately 30 min) resulted in a similar increase in P(o). In addition, this also increased the number (N) of active ENaC in the apical membrane. Similar to P(o), increases in N were sensitive to inhibitors of AC. Stressing animals with water and salt restriction separately and jointly revealed an important effect of vasopressin: conservation of water and Na+ each independently increased ENaC activity and jointly had a synergistic effect on channel activity. These results demonstrate a quantitatively important action of vasopressin on ENaC suggesting that distal nephron Na+ reabsorption mediated by this channel contributes to maintenance of water reabsorption. In addition, our results support that the combined actions of vasopressin and aldosterone are required to achieve maximally activated ENaC.
Bugaj
Vladislav
V
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
Pochynyuk
Oleh
O
Stockand
James D
JD
D000042:Absorption; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000450:Aldosterone / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004594:Electrophysiology; D062708:Epithelial Sodium Channel Agonists; D053503:Epithelial Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D018408:Patch-Clamp Techniques; D012076:Renal Agents / Q000494:pharmacology*; D012964:Sodium / Q000172:deficiency / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*
D000067956:Adenylyl Cyclase Inhibitors; D062708:Epithelial Sodium Channel Agonists; D053503:Epithelial Sodium Channels; D012076:Renal Agents; D014867:Water; D014667:Vasopressins; D001127:Arginine Vasopressin; D000450:Aldosterone; D012964:Sodium; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases
Am J Physiol. 1987 Feb;252(2 Pt 2):F331-7
3812744
Am J Physiol Renal Physiol. 2008 Oct;295(4):F889-900
18632802
Am J Physiol. 1999 Oct;277(4):F575-9
10516282
Exp Neurol. 2001 Oct;171(2):227-34
11573975
Endocrinology. 2005 Dec;146(12):5079-85
16150899
Pflugers Arch. 2000 Mar;439(5):579-87
10764218
Am J Physiol. 1992 Oct;263(4 Pt 1):C825-37
1329547
Proc Natl Acad Sci U S A. 1997 Oct 14;94(21):11710-5
9326675
Hypertension. 2001 Nov;38(5):1143-9
11711512
Kidney Int. 1984 Nov;26(5):725-32
6097738
Biochim Biophys Acta. 1988 Dec 9;972(3):320-30
3196765
Am J Physiol Renal Physiol. 2000 Jul;279(1):F46-53
10894786
Kidney Int. 1972 Apr;1(4):224-31
4671214
Am J Physiol Renal Physiol. 2008 Oct;295(4):F1063-70
18667482
J Am Soc Nephrol. 2009 Apr;20(4):721-9
19158355
Kidney Int. 2006 Mar;69(6):1024-32
16528252
Am J Physiol Renal Physiol. 2009 Jan;296(1):F10-24
18508877
Semin Nephrol. 2008 May;28(3):217-26
18519083
Pflugers Arch. 2000 Mar;439(5):610-7
10764221
Am J Physiol. 1990 Jul;259(1 Pt 2):R53-60
2375429
Am J Physiol. 1990 Nov;259(5 Pt 2):F823-31
1700630
Physiol Rev. 1997 Apr;77(2):359-96
9114818
J Am Soc Nephrol. 2007 Jun;18(6):1679-87
17475815
Am J Physiol. 1988 May;254(5 Pt 2):F739-46
2834967
J Clin Invest. 1986 Jan;77(1):136-41
3080471
J Biol Chem. 2008 Dec 26;283(52):36599-607
18981175
J Membr Biol. 1995 Mar;144(2):93-110
7595948
J Gen Physiol. 2002 Jul;120(1):71-85
12084777
Am J Physiol. 1991 May;260(5 Pt 1):C1071-84
1852105
J Clin Invest. 1980 Aug;66(2):234-42
6156951
Kidney Int. 2000 Apr;57(4):1313-8
10760060
Cell. 2001 Feb 23;104(4):545-56
11239411
Physiol Rev. 2007 Oct;87(4):1083-112
17928581
Kidney Int Suppl. 1996 Dec;57:S35-41
8941920
Pflugers Arch. 2009 May;458(1):111-35
19277701
Am J Physiol. 1971 Jun;220(6):1825-32
5087832
J Biol Chem. 2001 Jan 26;276(4):2775-9
11035038
J Am Soc Nephrol. 2005 Jul;16(7):1920-8
15888562
Sci Signal. 2009 Jul 14;2(79):pe41
19602703
Am J Physiol. 1992 Mar;262(3 Pt 2):F454-61
1558162
Am J Physiol. 1997 Nov;273(5):R1726-33
9374816
Am J Physiol Renal Physiol. 2002 Aug;283(2):F221-35
12110505
J Clin Invest. 1962 Apr;41:702-9
14482265
J Clin Invest. 1986 Apr;77(4):1291-8
2420830
Am J Physiol. 1990 Jul;259(1 Pt 2):F147-56
2375388
Pflugers Arch. 1987 Jun;409(1-2):81-92
2441357
J Gen Physiol. 2005 Jan;125(1):81-101
15623897
Proc Natl Acad Sci U S A. 1999 Feb 16;96(4):1727-31
9990092
Gen Comp Endocrinol. 2006 May 15;147(1):85-92
16405890
Am J Physiol. 1966 Jul;211(1):255-9
5911047
Cardiovasc Res. 2001 Aug 15;51(3):372-90
11476728
Am J Physiol. 1999 Mar;276(3):G567-71
10070030