1. Chronic ligation of the bile duct in dogs is associated with salt retention and a blunted natriuretic response to extracellular volume expansion. The mechanism of this phenomenon has not been clarified.
2. We have examined the influence of chronic β-adrenergic blockade on sodium excretion in dogs with bile-duct ligation during extracellular hypotonic volume expansion.
3. Urinary excretion of sodium and fractional excretion of sodium rose significantly after 5 days of oral dl-propranolol administration to dogs with bile-duct ligation.
4. The antinatriuresis after bile-duct ligation was not followed by a significant alteration in the mean peripheral plasma renin activity as compared with control values.
5. It is suggested that propranolol can partially reverse the antinatriuresis of chronic bile-duct ligation, and that this is mediated by an extrarenal effect of the β-adrenergic blockade.