15087
A dose - dependent inhibition was observed for the enzyme activities of Na ( + ) - K ( + ) - ATPase and Ca ( 2 + ) - ATPase in the gills after the fish were exposed for 90 days .
 Na ( + ), K ( + ), Ca ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Na ( + ), K ( + ), Ca ( 2 + )