3013
To further investigate ion and osmoregulation , Na ( + ) / K ( + ) - ATPase activities in gill and rectal gland were analysed as well as rates of ammonia and urea excretion .
 Chemical: Na ( + ); Chemical: K ( + ); Chemical: ammonia; Chemical: urea
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Na ( + ); Chemical: K ( + ); Chemical: ammonia; Chemical: urea