<prompt> Most impoant buffer in interstitial fluid:PhosphateBicarbonateHistidineProtein  <response>: Principal buffers in body fluids: Blood H2CO3 H HCO3-HProt complex H Prot-HHb H Hb- Interstitial fluid H2CO3H HCO3- Intracellular fluid HProt complex H Prot-H2PO4- H HPO42- 