Possible role of the membrane potential in serum-stimulated uptake of amino acid in a diploid human fibroblast

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:7302941

Villereal, Mitchel L.; Cook, John S.

The Na/sup +/-dependent accumulation of ..cap alpha..-aminoisobutyric acid (AIB), measured in normal growing and quiescent (serum-derived) HSWP cells (human diploid fibroblast), was found to be 2-fold higher (AIB/sub in//AIB/sub out/ = 20 to 25) under normal growing conditions. Serum stimulation of quiescent cells increases their AIB concentrating capacity by approximately 70 percent within 1 hr. These observations suggest that the driving forces for AIB accumulation may be reversibly influenced by the serum concentration of the growth medium. Addition of valinomycin (Val) to cells pre-equilibrated with AIB causes an enhanced accumulation of AIB, suggesting that the membrane potential can serve as a driving force for AIB accumulation. After pre-equilibration with AIB in 6 mM K/sup +/, transition to 94 mM K/sup +/ with Val results in a marked and rapid net loss of AIB. The effect of Val on the accumulation of AIB is greatest in quiescent cells, with the intracellular AIB concentrations reaching those seen in both Val-stimulated, normal cells and Val-stimulated, serum-stimulated cells. By adjusting (K/sup +/)/sub 0/, in the presence of Val, the membrane potential of growing cells can be matched to that of quiescent cells or vice versa. The resultant AIB accumulating capacity is characteristic of the membrane potential rather than of the growth state. In summary, these data suggest that the accumulation of AIB in HSWP cells may be influenced by changes in membrane potential and that a serum-associated membrane hyperpolarization could be partly responsible for the increased capacity for AIB accumulation in serum-stimulated cells.

• Research Organization: Tennessee Univ., Oak Ridge (USA). Graduate School of Biomedical Sciences; Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7302941
• Report Number(s): CONF-770348--1
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
550300* -- Cytology
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AMINOBUTYRIC ACID
ANIMAL CELLS
ANTIBIOTICS
ATOMIC IONS
BIOCHEMISTRY
BLOOD SERUM
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHEMISTRY
CONNECTIVE TISSUE CELLS
CULTURE MEDIA
DRUGS
FIBROBLASTS
IONS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
SODIUM IONS
SOMATIC CELLS
UPTAKE