Atrial Natriuretic Peptide in Rats with Experimental Cirrhosis of the Liver without Ascites

Plasma levels of atrial natriuretic peptide (ANP) have been measured in eight sodium-retaining cirrhotic nonascitic rats and eight control animals before and after extracellular volume expansion by isotonic saline infusion (30 ml/kg BW, 20 min). In addition, disappearance of [125I]ANP was studied in six control and six cirrhotic rats. The effect of infusing synthetic rat ANP-(1–28) (1 μg) on mean arterial pressure and renal function has been also studied. In basal conditions, cirrhotic rats showed higher ANP plasma levels than control animals (71.1 ± 16.6 vs. 43.9 ± 5.1 pg/ml; P < 0.05). After extracellular volume expansion, ANP increased in both control and cirrhotic rats; the increase in cirrhotic was higher than that in control rats (88 ± 27% vs. 33 ± 8%; P < 0.05). Disappearance of iodinated ANP from plasma was identical in control and cirrhotic rats. ANP infusion induced a larger decrease in mean arterial pressure in control (21 ± 5%) than in cirrhotic rats (9 ± 2.5%). ANP induced comparable increase...