Two-channel transporter versus a single-channel Na+-dependent transporter for glucose and amino acids in rat and turtle.
Conditions in rat and turtle small intestine tissue where glucose and glycine transport are inhibited while glucose-induced Na+ transport is preserved are described. The generally accepted model for the Na(+)-dependent transporter (a single channel for the Na+ and nutrient) does not account for the data obtained from an analysis of the interaction between the transport of glucose, glycine, and Na+ at different temperatures and the effect of inhibitors on these processes. The phenomenon of uncoupling of Na+ and nutrient transport can best be described by a two-channel model with a gate mechanism. According to this model, the Na(+)-dependent transporter has at least two channels: one for Na+ and another for nutrients. The model provides for the passage of Na+ in both directions along a channel opened by glucose, and accounts for changes in the stoichiometric ratio of Na+: glucose transport. Experiments are reported that confirm these theoretical predictions.
Ugolev
A M
AM
Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow.
Metel'skii
S T
ST
D000596:Amino Acids / Q000493:pharmacokinetics*; D000818:Animals; D001693:Biological Transport, Active; D004305:Dose-Response Relationship, Drug; D005998:Glycine / Q000378:metabolism / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D015640:Ion Channel Gating; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010695:Phlorhizin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000502:physiology*; D012969:Sodium Fluoride; D013696:Temperature; D014426:Turtles
D000596:Amino Acids; D009004:Monosaccharide Transport Proteins; D015222:Sodium Channels; D012969:Sodium Fluoride; D012964:Sodium; D010695:Phlorhizin; D005998:Glycine