title: The Effect and Underlying Mechanism of Ethanol on Intracellular H(+) -Equivalent Membrane Transporters in Human Aorta Smooth Muscle Cells.
abstract: The presence of intracellular pH (pHi ) regulators, including Na(+) -H(+) exchanger (NHE), Na(+) -HCO3- co-transporter (NBC), Cl(-) /OH(-) exchanger (CHE), and Cl(-) /HCO3- exchanger (AE), have been confirmed in many mammalian cells. Alcohol consumption is associated with increased risk of cardiovascular disorder. The aims of the study were to identify the possible transmembrane pHi regulators and to explore the effects of ethanol (EtOH) (10 to 300 mM) on the resting pHi and pHi regulators in human aorta smooth muscle cells (HASMCs).
  
  
  
  HASMCs were obtained from patients undergoing heart transplant. The pHi was measured by microspectrofluorimetry with the pH-sensitive dye, BCECF-AM.
  
  
  
  The following results are obtained. (i) In cultured HASMCs, the resting pHi was 7.19 ± 0.04 and 7.13 ± 0.02 for HEPES- and CO2 /HCO3--buffered solution, respectively. (ii) Two different Na(+) -dependent acid-equivalent extruders, including NHE and Na(+) -coupled HCO3- transporter, functionally coexisted. (iii) Two different Cl(-) -dependent acid loaders (CHE and AE) were functionally identified. (iv) EtOH induced a biphasic, concentration-dependent change in resting pHi (+0.25 pH unit at 100 mM but only +0.05 pH unit at 300 mM) in bicarbonate-buffered solution, while caused a concentration-dependent decrease in resting pHi (-0.06 pH unit at 300 mM) in HEPES-buffered solution. (v) The effect of EtOH on NHE activity was also biphasic: increase of 40% at lower concentration of 10 mM, followed by decrease of 30% at higher concentration of 300 mM. (vi) The increase in Na(+) -coupled HCO3- transporter activity by EtOH was concentration dependent. (vii) The effect of EtOH on CHE and AE activities was both biphasic: increase of ~25% at 30 mM, followed by decrease of 10 to 25% at 100 mM, and finally increase of 15 to 20% at 300 mM.
  
  
  
  This study demonstrated that 2 acid extruders and 2 acid loaders coexisted functionally in HASMCs and that EtOH induced a biphasic, concentration-dependent change in resting pHi by altering the activity of the 2 acid extruders, NHE and Na(+) -coupled HCO3- transporter, and the 2 acid loaders, CHE and AE.
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shih-Hurng
authors.initials: SH
authors.lastname: Loh
authors.affiliation: Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Lee
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Dentistry, Division of Orthodontics & Dentofacial Orthopedics and Pedodontics, Tri-Service General Hospital, Taipei, Taiwan.|School of Dentistry, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Gunng-Shinng
authors.initials: GS
authors.lastname: Chen
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ching-Hsia
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chan-Jun
authors.initials: CJ
authors.lastname: Tsao
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shou-Jou
authors.initials: SJ
authors.lastname: Shih
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Chou
authors.affiliation: Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.|Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chien-Sung
authors.initials: CS
authors.lastname: Tsai
authors.affiliation: Department of Surgery, Division of Cardiovascular Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.|Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.|School of Medicine, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Tsai
mesh_terms: D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D027963:Chloride-Bicarbonate Antiporters / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology*; D008297:Male; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology
chemical_list: D027963:Chloride-Bicarbonate Antiporters; D026901:Membrane Transport Proteins; D017923:Sodium-Hydrogen Exchangers; D000431:Ethanol
keywords: Alcohol/Ethanol; Cl−/HCO3− Exchanger (AE); Human Aorta Smooth Muscle Cells; Intracellular pH (pHi) Regulators; Na+-H+ Exchanger