opyright o The MeGraw-Hill Companies, Inc, Permission required for reproduction or display Extracellular fluid Intracellular fluid Cotransport(同向转运) the ion and the second solute cross the membrane in the same direction High Na Low Nat (e.g. Na*-glucose, Na*-amino acid Cotransport cotransport) LowⅩ High X Extracellular fluid Countertransport(逆向转运) Intracellular fluid the ion and the second solute move in opposite directions g Na*-Ca2*, Na+-H* exchange) High Na* - y Low Na Countertransport High X LowⅩCotransport（同向转运） the ion and the second solute cross the membrane in the same direction (e.g. Na+-glucose, Na+-amino acid cotransport) Countertransport（逆向转运） the ion and the second solute move in opposite directions (e.g. Na+-Ca2+, Na+-H+ exchange)