Fig. 1. Effect of hypotonic shock in isolated opercular epithelia mounted in symmetrical saline. (A) Example trace of time course of hypotonic shock on V_t, a 1 h duration period in hypotonic conditions and overshoot after restoration of isotonic conditions. (B) The size of the overshoot is a function of the period of hypotonic exposure; short periods yield no overshoot, longer periods yield larger overshoot in current, indicative of regulatory volume decrease during long hypotonic exposure.