... in the response to high NH 4 + (1 mmol l –1 ) only on gill arch I ( P <0.05). Fig. 7. [Ca2+]i responses to perfusion of high K+ (30 mmol l–1) or high NH4+ (1 mmol l–1) Cortland saline in NECs from different gill arches of control trout and of trout chronically exposed to HEA [250 μmol l–1 (NH4)2SO4] for 1...