The marked decrease in V-ATPase
specific activity in D. pagei posterior gills in response to salinity
acclimation, reaching 3-fold lower values in 15‰ compared to fresh
water, is consistent with the down-regulation of ion uptake mechanisms
until ionic regulation fails. In addition to a role in osmoregulatory
ion uptake, the crustacean gill V-ATPase is also involved in acid-base
regulation via H+ (Tresguerres et al., 2008) and ammonia excretion.