Effect of membrane potential on Na/sup +/-dependent sugar transport by ATP-depleted intestinal cells

Journal Article · Tue Jan 01 04:00:00 EST 1980 · Am. J. Physiol.: Cell Physiol.; (United States)

OSTI ID:5632525

Carter-Su, C; Kimmich, G A

The role of the membrane potential as a component of the thermodynamic driving force and as a determinant of kinetic parameters of Na/sup +/-dependent sugar transport was investigated using ATP-depleted isolated chicken intestinal cells. Inside-negative membrane potentials were established by incubating K/sup +/-loaded rotenone-inhibited cells with valinomycin in a low K/sup +/ medium. Overshoots of 3-0-methylglucose (3-OMG) accumulation as high as 10-fold were observed in the presence of valinomycin even in the absence of a Na/sup +/ chemical gradient. The magnitude of overshoot was diminished by decreasing the magnitude of the imposed K/sup +/ gradient and abolished altogether when nigericin was also included. An Eadie-Hofstee plot of initial flux data showed that the imposed membrane potential increases the V/sub max/ of tranport in the absence of a chemical gradient for Na/sup +/ from 3 to 12 nmol 3-OMG.mg protein/sup -1/.min/sup -1/. The K/sub T/ is not significantly altered. Similar kinetic results were obtained when a membrane potential as well as a Na/sup +/ gradient were imposed. These results suggest that the membrane potential is a more important contributor to alterations in the kinetics of transport than the Na/sup +/ chemical potential.

• Research Organization: Univ. of Rochester Medical Center, NY
• OSTI ID: 5632525
• Journal Information: Am. J. Physiol.: Cell Physiol.; (United States), Journal Name: Am. J. Physiol.: Cell Physiol.; (United States) Vol. 238; ISSN AJCPD
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550300 -- Cytology
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
ATP
BIOCHEMICAL REACTION KINETICS
BODY
BUILDUP
CARBOHYDRATES
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
DIGESTIVE SYSTEM
ELECTRIC POTENTIAL
GASTROINTESTINAL TRACT
GLUCOSE
HEXOSES
INTESTINES
ION EXCHANGE MATERIALS
IONS
KINETICS
MATERIALS
MEASURING METHODS
MEMBRANES
MONOSACCHARIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
POTASSIUM IONS
QUANTITY RATIO
REACTION KINETICS
SACCHARIDES
SODIUM IONS
UPTAKE