Such a mechanism, which is closely linked to osmoregulation, is
suggested to be a two-step process (Weihrauch et al., 1999). Based on
past experiments, the currentmodel suggests thatNH4
+can substitute for
K+ via basolaterally located Na+/K+-ATPase activity, and NH4
+ is then
excreted to the environment via an apically located Na+/NH4
+ transporters