title: Independent modulation by food supply of two distinct sodium-activated D-glucose transport systems in the guinea pig jejunal brush-border membrane.
abstract: D-glucose transport across the intestinal brush-border membrane involves two transport systems designated here as systems 1 and 2. Kinetic properties for both D-glucose and methyl alpha-D-glucopyranoside transport were measured at 35 degrees C by using brush-border membrane vesicles prepared from either control, fasted (48 hr), or semistarved (10 days) animals. The results show the following: (i) The sugar influx rate by simple diffusion was identical under either altered condition. (ii) Semistarvation stimulated D-glucose uptake by system 2 (both its Vmax and Km increased), whereas system 1 was untouched. (iii) Fasting increased the capacity of system 1 without affecting either Km of system 1 or Vmax and Km of system 2. The effect of fasting on Vmax of system 1 cannot be attributed to indirect effects from changes in ionic permeability because the kinetic difference between control and fasted animals persisted when the membrane potential was short-circuited with equilibrated K+ and valinomycin. This work provides further evidence for the existence of two distinct sodium-activated D-glucose transport systems in the intestinal brush-border membrane, which adapt independently to either semistarvation or fasting.
authors.affiliation: Centre de Recherches sur la Nutrition, Meudon, France.
authors.forename: E
authors.initials: E
authors.lastname: Brot-Laroche
authors.forename: M T
authors.initials: MT
authors.lastname: Dao
authors.forename: A I
authors.initials: AI
authors.lastname: Alcalde
authors.forename: B
authors.initials: B
authors.lastname: Delhomme
authors.forename: N
authors.initials: N
authors.lastname: Triadou
authors.forename: F
authors.initials: F
authors.lastname: Alvarado
mesh_terms: D000818:Animals; D004032:Diet; D004435:Eating; D005260:Female; D005947:Glucose / Q000378:metabolism; D006168:Guinea Pigs; D007583:Jejunum / Q000378:metabolism*; D007700:Kinetics; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology*; D013217:Starvation
chemical_list: D009004:Monosaccharide Transport Proteins; D012964:Sodium; D005947:Glucose