Aparticular co-transporter uses the concentration gradient of na+ to move an amino acid into the cell. what immediate effect would raising the extracellular na+ have? it would… a. increase the amino acid's rate of entry into the cell. b. block the movement of the amino acid into the cell. c. block the na+ / k+ pump. d. speed up the na+ / k+ pump. e. reverse the direction of the na+ / k+ pump so that it moves na+ and k+ down their concentration gradients.