Heterogeneous renal responses to atrial natriuretic factor. I. Chronic caval dogs

Atrial natriuretic factor (ANF) (175 ng · kg^-1 · min^-1) was administered to 14 normal, alert dogs and again after constriction of the thoracic vena cava. The average natriuresis observed in the dogs when they were normal was blunted by 55% when they developed ascites and were avidly retaining sodium. Of the 14 caval dogs, 7 showed a natriuretic response no different from the control phase while 7 showed no natriuresis at all in response to the ANF. Ten dogs were restudied when they entered a phase of sodium balance despite the persistence of ascites. All 10 dogs now responded to ANF, and 5 dogs previously not responding now showed a mean change of urinary sodium excretion rate (ΔU(na)V) of 204 μeq/min. The two groups could not be differentiated in terms of plasma volume, systemic or renal hemodynamics, or plasma levels of renin and aldosterone. We conclude that there is reversible attenuation of the ANF natriuretic effect in 50% of chronic caval dogs, which disappears when they lose avidity for sodium retention.