title: Study of Na+/H+ exchange-mediated pHi regulations in neuronal soma and neurites in compartmentalized microfluidic devices.
abstract: Regulation of intracellular pH (pH(i)) in neurons is crucial to maintain their physiological function. In the current study, newly-developed polydimethylsiloxane (PDMS) microfluidic devices were used to independently investigate pH(i) regulation in neuronal soma and neurites. Embryonic cortical neurons were cultured in PDMS microfluidic devices with soma growing in one chamber (seeded) and neurites extending through a set of perpendicular microchannels into the opposite parallel chamber (non-seeded). Neurons in the microchambers were characterized by the vital dye calcein-red, polarized mitochondria, and expression of neuronal specific beta-tubulin (type-III), axonal Tau-1 protein, dendritic microtubule associated protein (MAP-2), and Na(+)/H(+) exchanger isoform 1 (NHE-1). Neurites exhibited higher resting pH(i) than soma (7.16 +/- 0.09 vs. 6.90 +/- 0.15). The neurites had a proton extrusion rate 3.7-fold faster than in soma following NH(4)Cl prepulse-mediated acidification (p < 0.05). The difference in the pH(i) regulation rates between neurites and soma can be accounted for by the larger surface area to volume ratio in the neurites. Interestingly, pharmacological inhibition of NHE-1 activity blocked the pH(i) regulation in soma and in neurites by approximately 70% (p < 0.05). Taken together, our study demonstrated that the microfluidic devices provide a useful tool to study neuronal pH(i) regulation in soma and their neurites. We conclude that NHE-1 plays an important role in regulation of pH(i) in both compartments.
authors.affiliation: Dept of Neurological Surgery, University of Wisconsin Medical School, T513 Waisman Center, 1500 Highland Ave, Madison, WI 53705, USA.
authors.forename: Lucas
authors.initials: L
authors.lastname: Vitzthum
authors.forename: Xinzhi
authors.initials: X
authors.lastname: Chen
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Kintner
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Shing-Yan
authors.initials: SY
authors.lastname: Chiu
authors.forename: Justin
authors.initials: J
authors.lastname: Williams
authors.forename: Dandan
authors.initials: D
authors.lastname: Sun
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D045647:DNA Glycosylases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D016501:Neurites / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*
chemical_list: D045647:DNA Glycosylases; C473634:NEIL1 protein, human; D000254:Sodium-Potassium-Exchanging ATPase
references.citation: J Neurochem. 2006 Nov;99(4):1224-36
references.pmid: 17018119
references.citation: Physiol Rev. 2003 Oct;83(4):1183-221
references.pmid: 14506304
references.citation: Biomed Microdevices. 2009 Dec;11(6):1145-53
references.pmid: 19554452
references.citation: J Neurosci. 2007 Jul 11;27(28):7438-46
references.pmid: 17626204
references.citation: J Neurophysiol. 1998 Oct;80(4):1702-12
references.pmid: 9772233
references.citation: J Neurosci. 2005 Dec 7;25(49):11256-68
references.pmid: 16339021
references.citation: Lab Chip. 2002 Aug;2(3):131-4
references.pmid: 15100822
references.citation: Am J Physiol Cell Physiol. 2004 Jul;287(1):C12-21
references.pmid: 15013953
references.citation: Proc Natl Acad Sci U S A. 1977 Oct;74(10):4516-9
references.pmid: 270699
references.citation: Lab Chip. 2007 Jan;7(1):30-40
references.pmid: 17180203
references.citation: Nat Methods. 2005 Aug;2(8):599-605
references.pmid: 16094385
references.citation: Pflugers Arch. 2004 Feb;447(5):549-65
references.pmid: 12845533
references.citation: Am J Physiol Cell Physiol. 2005 Oct;289(4):C934-45
references.pmid: 15901600
references.citation: J Neurophysiol. 1999 Jun;81(6):2627-35
references.pmid: 10368383
references.citation: J Neurosci. 2009 Jul 15;29(28):8946-59
references.pmid: 19605632
references.citation: Trends Neurosci. 1992 Oct;15(10):396-402
references.pmid: 1279865
references.citation: Front Biosci. 2007 Jan 01;12:762-70
references.pmid: 17127336
references.citation: Neuroscience. 1997 Jul;79(2):591-603
references.pmid: 9200742
references.citation: Annu Rev Biomed Eng. 2001;3:335-73
references.pmid: 11447067
references.citation: Genes Dev. 2000 Dec 1;14(23):2919-37
references.pmid: 11114882
references.citation: Glia. 1993 Aug;8(4):241-8
references.pmid: 8406681
references.citation: Exp Neurol. 2009 Jul;218(1):124-8
references.pmid: 19409381
references.citation: Lab Chip. 2004 Apr;4(2):91-7
references.pmid: 15052346
references.citation: Nat Neurosci. 2009 Jul;12(7):857-63
references.pmid: 19503084
references.citation: J Neurochem. 2008 Aug;106(4):1563-76
references.pmid: 18507737
references.citation: J Gen Physiol. 1976 Jan;67(1):91-112
references.pmid: 1460
references.citation: J Biol Chem. 2007 Sep 21;282(38):28274-84
references.pmid: 17664275