Adaptational Responses of Rainbow Trout to Lowered External Nacl Concentration: Contribution of the Branchial Chloride Cell

ABSTRACT Whole-body ionic fluxes and gill chloride cell (CC) morphology were monitored in rainbow trout (Salmo gairdneri) exposed acutely or chronically to natural fresh water (NFW; [Na+]=0·120 mmol l−1; [Cl−]=0·164 mmol l−1) or artificially prepared fresh water with reduced [NaCl] (AFW; [Na+]=0·017 mmoll−1; [Cl−]=0·014mmoll−1). Net fluxes of Na+ and Cl− became extremely negative (indicating net NaCl loss to the environment) upon immediate …