because some compartmentation of the sbfi was visible and because the indicator properties are somewhat affected by cytoplasm , the relationship between intracellular free na+ [ ( na+ ] i and the 340/385 nm excitation ratio of the indicator was calibrated in situ using poreforming antibiotics to equilibrate cytosolic [ na+ ] [ ( na+ ] i ) with extracellular [ na+ ] .
C0010834
cytoplasm
C1383501
cytosolic