Am Polit Sci Rev 86:404?17. 37. Maier-Rigaud FP, Martinsson P, Staffiero G (2010) Ostracism and the provision of a public good: Experimental evidence. J Econ Behav Organ 73:387?95. 38. Mason WA, Watts DJ (2009) Financial incentives and the performance of crowds. Proceedings of the ACM SIGKDD Workshop on Human Computation (Association for Computing Machinery, New York), pp 77?5. 39. Horton J, Rand D, Zeckhauser R (2011) The online laboratory: conducting experiments in a real labor market. Exp Econ 14:399?25. 40. Paolacci G, Chandler J, Ipeirotis PG (2010) Running experiments on Amazon Mechanical Turk. Judgm Decis Mak 5:411?19. 41. Mason W, Watts DJ (2012) Collaborative learning in networks. Proc Natl Acad Sci USA 109:764?69.14368 | www.pnas.org/cgi/doi/10.1073/pnas.Wang et al.
Aldosterone-independent regulation of the epithelial Na+ channel (ENaC) by vasopressin in adrenalectomized miceElena Mironovaa, Vladislav Bugaja, Karl P. Roosb, Donald E. Kohanb, and James D. Stockanda,a Department of Physiology, University of Texas Health Science Center, San Antonio, TX 78229; and bDivision of Nephrology, University of Utah School of Medicine, Salt Lake City, UTEdited by Maurice B. Burg, National Heart, Lung, and Blood Institute, Bethesda, MD, and approved May 2, 2012 (received for review February 2, 2012)The epithelial Na+ channel (ENaC) in the aldosterone-sensitive distal nephron (ASDN) is under negative-feedback regulation by the renin ngiotensin ldosterone system in protection of sodium balance and blood pressure. We test here whether aldosterone is necessary and sufficient for ENaC expression and activity in the ASDN. Surprisingly, ENaC expression and activity are robust in adrenalectomized (Adx) mice. Exogenous mineralocorticoid increases ENaC activity equally well in control and Adx mice. Plasma [AVP] is significantly elevated in Adx vs. control mice. Vasopressin (AVP) stimulates ENaC. Inhibition of the V2 AVP receptor represses ENaC activity in Adx mice. The absence of aldosterone combined with elevated AVP release compromises normal feedback regulation of ENaC in Adx mice in response to changes in sodium intake. These results demonstrate that aldosterone is sufficient but not necessary for ENaC activity in the ASDN. Aldosterone-independent stimulation by AVP shifts the role of ENaC in the ASDN from protecting Na+ balance to promoting water reabsorption. This stimulation of ENaC likely contributes to the hyponatremia of adrenal insufficiency.epithelial transport sodium wasting| hypertension | sodium excretion | diabetes insipidus |enal sodium excretion is fine-tuned in the aldosterone-sensitive distal nephron (ASDN). Here, the activity of the epithelial Na+ channel (ENaC) is limiting for sodium Sch66336 price reabsorption (reviewed in refs. 1 and 2). ENaC serves as the apical entry pathway for GSK2256098 side effects electrogenic Na+ reabsorption through principal cells. Normal ENaC function is required for proper sodium balance and, thus, normal blood pressure. Gain-of-function mutations in ENaC cause inappropriate renal sodium retention and consequent increases in mean arterial pressure (2, 3). Inhibition of ENaC corrects the renal and blood pressure phenotypes resulting from such mutations. Loss-of-function mutations in ENaC, in contrast, cause renal sodium wasting and corresponding decreases in blood pressure (2, 4). The activity of ENaC is under negative-feedback regulation by the renin ngiotensin ldosterone system (RAAS; ref. 1). The mineralocorticoid, aldosterone, is the.Am Polit Sci Rev 86:404?17. 37. Maier-Rigaud FP, Martinsson P, Staffiero G (2010) Ostracism and the provision of a public good: Experimental evidence. J Econ Behav Organ 73:387?95. 38. Mason WA, Watts DJ (2009) Financial incentives and the performance of crowds. Proceedings of the ACM SIGKDD Workshop on Human Computation (Association for Computing Machinery, New York), pp 77?5. 39. Horton J, Rand D, Zeckhauser R (2011) The online laboratory: conducting experiments in a real labor market. Exp Econ 14:399?25. 40. Paolacci G, Chandler J, Ipeirotis PG (2010) Running experiments on Amazon Mechanical Turk. Judgm Decis Mak 5:411?19. 41. Mason W, Watts DJ (2012) Collaborative learning in networks. Proc Natl Acad Sci USA 109:764?69.14368 | www.pnas.org/cgi/doi/10.1073/pnas.Wang et al.
Aldosterone-independent regulation of the epithelial Na+ channel (ENaC) by vasopressin in adrenalectomized miceElena Mironovaa, Vladislav Bugaja, Karl P. Roosb, Donald E. Kohanb, and James D. Stockanda,a Department of Physiology, University of Texas Health Science Center, San Antonio, TX 78229; and bDivision of Nephrology, University of Utah School of Medicine, Salt Lake City, UTEdited by Maurice B. Burg, National Heart, Lung, and Blood Institute, Bethesda, MD, and approved May 2, 2012 (received for review February 2, 2012)The epithelial Na+ channel (ENaC) in the aldosterone-sensitive distal nephron (ASDN) is under negative-feedback regulation by the renin ngiotensin ldosterone system in protection of sodium balance and blood pressure. We test here whether aldosterone is necessary and sufficient for ENaC expression and activity in the ASDN. Surprisingly, ENaC expression and activity are robust in adrenalectomized (Adx) mice. Exogenous mineralocorticoid increases ENaC activity equally well in control and Adx mice. Plasma [AVP] is significantly elevated in Adx vs. control mice. Vasopressin (AVP) stimulates ENaC. Inhibition of the V2 AVP receptor represses ENaC activity in Adx mice. The absence of aldosterone combined with elevated AVP release compromises normal feedback regulation of ENaC in Adx mice in response to changes in sodium intake. These results demonstrate that aldosterone is sufficient but not necessary for ENaC activity in the ASDN. Aldosterone-independent stimulation by AVP shifts the role of ENaC in the ASDN from protecting Na+ balance to promoting water reabsorption. This stimulation of ENaC likely contributes to the hyponatremia of adrenal insufficiency.epithelial transport sodium wasting| hypertension | sodium excretion | diabetes insipidus |enal sodium excretion is fine-tuned in the aldosterone-sensitive distal nephron (ASDN). Here, the activity of the epithelial Na+ channel (ENaC) is limiting for sodium reabsorption (reviewed in refs. 1 and 2). ENaC serves as the apical entry pathway for electrogenic Na+ reabsorption through principal cells. Normal ENaC function is required for proper sodium balance and, thus, normal blood pressure. Gain-of-function mutations in ENaC cause inappropriate renal sodium retention and consequent increases in mean arterial pressure (2, 3). Inhibition of ENaC corrects the renal and blood pressure phenotypes resulting from such mutations. Loss-of-function mutations in ENaC, in contrast, cause renal sodium wasting and corresponding decreases in blood pressure (2, 4). The activity of ENaC is under negative-feedback regulation by the renin ngiotensin ldosterone system (RAAS; ref. 1). The mineralocorticoid, aldosterone, is the.
