ABSTRACT
Rainbow trout were infused continuously for 24 h with epinephrine in order to elevate circulating levels to those measured during periods of acute extracellular acidosis (about 5× 10−8 mol I−1). Concomitant effects on branchial solute fluxes were evaluated. Epinephrine infusion caused complex and differential adjustments of Na+ and Cl− unidirectional fluxes (influx and efflux) resulting in a significant elevation of the arithmetic difference between Na+ and Cl− net fluxes 
. A significant correlation existed between 
and net branchial acid excretion 
, thereby suggesting a role for epinephrine in piscine acid-base regulation. The stimulation of by epinephrine was due primarily to a reduction in the excretion of titratable acid (JTA) accompanied by non-significant changes in ammonia excretion (JAmm) The results are discussed with respect to a role for epinephrine in regulating acid-base disturbances by interacting with branchial ionic exchange mechanisms.
