The role of atrial natriuretic peptide (ANP) on jejunal net fluid transport was 
studied in intact rats as well as in rats subjected to a perivascular 
denervation of the intestinal segment. In rats with intact nerves, an acute 
volume expansion with 5% albumin (10% of estimated blood volume) decreased 
jejunal net fluid absorption by approximately 70% compared to control animals 
not subjected to volume expansion. After a perivascular denervation of the 
intestinal segment, the acute volume expansion reversed net fluid absorption 
into a net fluid secretion. In order to reduce the volume expansion-induced 
endogenous release of ANP, one group of rats was subjected to a right atrial 
appendectomy 7 days prior to the experiments. In these animals, the intestinal 
response to the same 10% volume load was blunted compared to controls. 
Administration of rat alpha-ANP (99-126; 5 micrograms kg-1 i.v.) induced effects 
similar to those of volume expansion both in rats with intact perivascular 
nerves as well as in denervated animals. Volume expansion increased mean 
arterial pressure (MAP) as well as central venous pressure and decreased heart 
rate (HR) in all groups. When exogenous ANP was administered, a fall in MAP was 
seen, while HR remained unchanged. In conclusion, these data strongly indicate a 
physiological role for ANP in jejunal fluid transfer in response to acute volume 
expansion.