PMID- 2841867
OWN - NLM
STAT- MEDLINE
DCOM- 19880914
LR  - 20171213
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 255
IP  - 2 Pt 1
DP  - 1988 Aug
TI  - Na+ and H+ transport in human jejunal brush-border membrane vesicles.
PG  - G206-11
AB  - We have examined pH gradient-driven Na+ uptake and Na+-driven H+ transport in 
      brush-border membrane vesicles prepared from jejunal tissue obtained from organ 
      donors by measuring the influx of 22Na and the fluorescence quenching of acridine 
      orange (AO). Vesicle preparation by either Ca2+ or Mg2+ precipitation showed no 
      difference in 22Na uptake or AO fluorescence quenching and dissipation. An 
      outward H+ gradient [intravesicular pH (pHi) 5.5; extravesicular pH (pHo) 7.5] 
      induced a Na+ uptake "overshoot" of threefold over equilibrium, whereas the 
      absence of an H+ gradient (at either pH 5.5 or 7.5) did not produce an overshoot. 
      Voltage clamping by Ki+ = Ko+ plus valinomycin reduced the overshoot by 50%. The 
      initial rate of pH-driven Na+ uptake in voltage-clamped vesicles was related to 
      [Nao+] (Km = 29 mM and Vmax = 9.5 nmol.mg protein-1.3 s-1). Amiloride inhibited 
      this uptake in voltage-clamped vesicles (Ki = 99 microM). Dissipation of AO 
      fluorescence quench in vesicles with a preformed internal acid gradient was 
      hastened by Nao+ as well as voltage clamping in the absence of Na+. In vesicles 
      without a pH gradient, internal Na+, as well as a diffusion potential (Ki+ 100; 
      Ko+ 0 plus valinomycin) in the absence of Na+, induced AO quenching. External Na+ 
      and Li+, but not choline, acted to dissipate AO quenching induced by a diffusion 
      potential, and the rate of dissipation was unaffected by the presence of Cl-.Li+ 
      and NH4+, but not Cs+, K+, Rb+, or choline+, inhibited pH gradient-driven 22Na 
      uptake. We conclude that human jejunal brush-border membrane vesicles contain 
      conductive pathways for both Na+ and H+ and an Na+-H+ exchanger.
FAU - Kleinman, J G
AU  - Kleinman JG
AD  - Nephrology Section, Zablocki Veterans Administration Medical Center, Milwaukee, 
      Wisconsin.
FAU - Harig, J M
AU  - Harig JM
FAU - Barry, J A
AU  - Barry JA
FAU - Ramaswamy, K
AU  - Ramaswamy K
LA  - eng
GR  - AM-07267/AM/NIADDK NIH HHS/United States
GR  - AM-33349/AM/NIADDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Carrier Proteins)
RN  - 0 (Sodium-Hydrogen Exchangers)
RN  - 2001-95-8 (Valinomycin)
RN  - 7DZO8EB0Z3 (Amiloride)
RN  - 9NEZ333N27 (Sodium)
RN  - F30N4O6XVV (Acridine Orange)
RN  - RWP5GA015D (Potassium)
SB  - IM
MH  - Acridine Orange
MH  - Amiloride/pharmacology
MH  - Carrier Proteins/*metabolism
MH  - Humans
MH  - Hydrogen-Ion Concentration
MH  - Jejunum/*metabolism
MH  - Kinetics
MH  - Microvilli/drug effects/*metabolism
MH  - Potassium/pharmacology
MH  - Sodium/*metabolism
MH  - Sodium-Hydrogen Exchangers
MH  - Spectrometry, Fluorescence
MH  - Valinomycin/pharmacology
EDAT- 1988/08/01 00:00
MHDA- 1988/08/01 00:01
CRDT- 1988/08/01 00:00
PHST- 1988/08/01 00:00 [pubmed]
PHST- 1988/08/01 00:01 [medline]
PHST- 1988/08/01 00:00 [entrez]
AID - 10.1152/ajpgi.1988.255.2.G206 [doi]
PST - ppublish
SO  - Am J Physiol. 1988 Aug;255(2 Pt 1):G206-11. doi: 10.1152/ajpgi.1988.255.2.G206.