For the anti-ENaC antibodies used in the current studies (17). Antibodies to each of the three ENaC subunits were a gift from Mark A. Knepper (National Institutes of Health, Bethesda, MD) and have been characterized (17, 37). Kidney slices immunolabeled with anti-ENaC and anti-AQP2 antibodies were imaged with epifluorescence on an inverted microscope by using a 40?objective (1.4 NA) on a system built around a Zeiss Axiovert 200M equipped with DAPI, FITC, and CY5 excitation and emission purchase Anisomycin filters. Images were collected and analyzed with Slidebook 4.2 software. Refer to SI Methods for additional description. Analysis of Hormones and Electrolytes. Urinary and plasma electrolyte concentrations and osmolality were determined by using standard Y-27632 molecular weight procedures with a flame photometer and vapor pressure osmometer, respectively. Plasma corticosterone and AVP concentrations were quantified by using standard procedures with HPLC on a reversed-phase, cation exchange column (4.6 ?150 mm; 5-m particle size; part number C-18; fAlltech) and a competitive enzyme-linked immunoassay (Arg8-Vasopressin EIA kit; Enzo Life Sciences), respectively (38). Refer to SI Methods for additional description. Statistical Analysis and Data Presentation. Data are reported as mean ?SEM. Unpaired data were compared with a two-sided unpaired Student t test. The criterion for significance was P 0.05. For presentation, slow baseline drifts were corrected, and current data from some patches were software-filtered at 50 Hz.PNAS | June 19, 2012 | vol. 109 | no. 25 |PHYSIOLOGYACKNOWLEDGMENTS. We thank Dr. M. A. Javors, J. J. Sanchez, and C. R. Herrera for assistance quantifying plasma (corticosterone) with HPLC.This work was supported by National Institutes of Health Grant R01 DK59594 (to J.D.S.) and American Heart Association Fellowship 10POST3200019 (to V.B.).1. Kellenberger S, Schild L (2002) Epithelial sodium channel/degenerin family of ion channels: A variety of functions for a shared structure. Physiol Rev 82:735?67. 2. Rossier BC, Pradervand S, Schild L, Hummler E (2002) Epithelial sodium channel and the control of sodium balance: Interaction between genetic and environmental factors. Annu Rev Physiol 64:877?97. 3. Lifton RP, Gharavi AG, Geller DS (2001) Molecular mechanisms of human hypertension. Cell 104:545?56. 4. Geller DS (2005) Mineralocorticoid resistance. Clin Endocrinol (Oxf) 62:513?20. 5. Horisberger J-D, Diezi J (1983) Effects of mineralocorticoids on Na+ and K+ excretion in the adrenalectomized rat. Am J Physiol 245:F89 99. 6. Edmonds CJ (1960) Sodium excretion in the adrenalectomized rat after intravenous saline infusion. J Endocrinol 20:112?22. 7. G ez-S chez CE (1998) Primary aldosteronism and its variants. Cardiovasc Res 37: 8?3. 8. White PC (1994) Disorders of aldosterone biosynthesis and action. N Engl J Med 331: 250?58. 9. White PC (2004) Aldosterone synthase deficiency and related disorders. Mol Cell Endocrinol 217:81?7. 10. Kemendy AE, Kleyman T, Eaton DC (1992) Aldosterone alters the open probability of amiloride-blockable sodium channels in A6 epithelia. Am J Physiol 263:C825 837. 11. P ha J, Frindt G, Antonian L, Silver RB, Palmer LG (1993) Regulation of Na channels of the rat cortical collecting tubule by aldosterone. J Gen Physiol 102:25?2. 12. Palmer LG, Antonian L, Frindt G (1994) Regulation of apical K and Na channels and Na/K pumps in rat cortical collecting tubule by dietary K. J Gen Physiol 104:693?10. 13. Berger S, et al. (1998) Mineralocorticoi.For the anti-ENaC antibodies used in the current studies (17). Antibodies to each of the three ENaC subunits were a gift from Mark A. Knepper (National Institutes of Health, Bethesda, MD) and have been characterized (17, 37). Kidney slices immunolabeled with anti-ENaC and anti-AQP2 antibodies were imaged with epifluorescence on an inverted microscope by using a 40?objective (1.4 NA) on a system built around a Zeiss Axiovert 200M equipped with DAPI, FITC, and CY5 excitation and emission filters. Images were collected and analyzed with Slidebook 4.2 software. Refer to SI Methods for additional description. Analysis of Hormones and Electrolytes. Urinary and plasma electrolyte concentrations and osmolality were determined by using standard procedures with a flame photometer and vapor pressure osmometer, respectively. Plasma corticosterone and AVP concentrations were quantified by using standard procedures with HPLC on a reversed-phase, cation exchange column (4.6 ?150 mm; 5-m particle size; part number C-18; fAlltech) and a competitive enzyme-linked immunoassay (Arg8-Vasopressin EIA kit; Enzo Life Sciences), respectively (38). Refer to SI Methods for additional description. Statistical Analysis and Data Presentation. Data are reported as mean ?SEM. Unpaired data were compared with a two-sided unpaired Student t test. The criterion for significance was P 0.05. For presentation, slow baseline drifts were corrected, and current data from some patches were software-filtered at 50 Hz.PNAS | June 19, 2012 | vol. 109 | no. 25 |PHYSIOLOGYACKNOWLEDGMENTS. We thank Dr. M. A. Javors, J. J. Sanchez, and C. R. Herrera for assistance quantifying plasma (corticosterone) with HPLC.This work was supported by National Institutes of Health Grant R01 DK59594 (to J.D.S.) and American Heart Association Fellowship 10POST3200019 (to V.B.).1. Kellenberger S, Schild L (2002) Epithelial sodium channel/degenerin family of ion channels: A variety of functions for a shared structure. Physiol Rev 82:735?67. 2. Rossier BC, Pradervand S, Schild L, Hummler E (2002) Epithelial sodium channel and the control of sodium balance: Interaction between genetic and environmental factors. Annu Rev Physiol 64:877?97. 3. Lifton RP, Gharavi AG, Geller DS (2001) Molecular mechanisms of human hypertension. Cell 104:545?56. 4. Geller DS (2005) Mineralocorticoid resistance. Clin Endocrinol (Oxf) 62:513?20. 5. Horisberger J-D, Diezi J (1983) Effects of mineralocorticoids on Na+ and K+ excretion in the adrenalectomized rat. Am J Physiol 245:F89 99. 6. Edmonds CJ (1960) Sodium excretion in the adrenalectomized rat after intravenous saline infusion. J Endocrinol 20:112?22. 7. G ez-S chez CE (1998) Primary aldosteronism and its variants. Cardiovasc Res 37: 8?3. 8. White PC (1994) Disorders of aldosterone biosynthesis and action. N Engl J Med 331: 250?58. 9. White PC (2004) Aldosterone synthase deficiency and related disorders. Mol Cell Endocrinol 217:81?7. 10. Kemendy AE, Kleyman T, Eaton DC (1992) Aldosterone alters the open probability of amiloride-blockable sodium channels in A6 epithelia. Am J Physiol 263:C825 837. 11. P ha J, Frindt G, Antonian L, Silver RB, Palmer LG (1993) Regulation of Na channels of the rat cortical collecting tubule by aldosterone. J Gen Physiol 102:25?2. 12. Palmer LG, Antonian L, Frindt G (1994) Regulation of apical K and Na channels and Na/K pumps in rat cortical collecting tubule by dietary K. J Gen Physiol 104:693?10. 13. Berger S, et al. (1998) Mineralocorticoi.