5611
However , for a large number of compounds that are substrates for uptake and / or efflux transporters expressed at the tissue level , significant discrepancies are expected between unbound concentrations in blood and those in tissues .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None