Splanchnic Removal of Atrial Natriuretic Factor (ANF) in Man

In order to assess the effect of food ingestion on splanchnic
disposal of human alpha-atrial natriuretic peptide (ANF),
hepatic-intestinal removal of ANF was determined before and after a
test meal. Hepatic venous and arterial plasma samples were obtained
from six subjects, most of whom had only disorders of minor degree.
Hepatic blood flow (HBF) increased significantly after meal
ingestion (1.10 ± 0.17 [SEM] to 1.51 ± 0.26 L/min, P < .01).
Baseline arterial ANF (10.9 ± 3.1 pmol/L) did not change
significantly. In contrast, hepatic venous ANF increased after meal
intake (5.7 ± 2.0 to 8.4 ± 1.9 pmol/L, P < .05), and accordingly
the splanchnic fractional extraction decreased (0.53 ± 0.09 to 0.35
± 0.08), although this was not statistically significant.
Splanchnic clearance of ANF increased from 347 ± 90 mL/min to a
maximal value of 615 ± 158 mL/min (P < .05). Splanchnic removal
of ANF was 3.0 ± 0.5 pmol/min before and increased to a maximum
value (7.1 ± 2.2 pmol/min, P < .05) 35 minutes after ingestion
of the meal. Our results showed enhanced splanchnic removal of ANF
after food intake. This is due to increased hepatic-intestinal
clearance of the peptide consequent on increased splanchnic blood
flow, rather than altered fractional extraction of ANF.