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

Bendtsen, Flemming

Gerbes, Alexander L.

Henriksen, Jens H.

English

Open Access LMU

Splanchnic Removal of Human Alpha-Atria1 Natriuretic Peptide in Humans: Enhancement After Food Intake Jens H. Henriksen, Flemming Bendtsen, and Alexander L. Gerbes In order to assess the effect of food ingestion on splanchnic disposal of human alpha-atria1 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 [SEMI to 1.51 * 0.26 L/min, P < .Ol). Baseline arterial ANF (10.9 + 3.1 pmol/L) did not change significantly. In contrast, hepatic venous ANF increased after meal intake (5.7 f 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. Splenchnic clearance of ANF increased from 347 % 90 mL/min to a maximal value of 615 & 159 mL/min (P < .05). Splanchnic removal of ANF was 3.0 f 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 splenchnic blood flow, rather than altered fractional extraction of ANF. 0 1990 by W.B. Saunders Company. TRIAL natriuretic factor (human alpha-atria1 natri- A uretic peptide [human ANF 99-1261, abbreviation in this report: ANF) is important in the regulation of salt-water homeostasis and blood pressure.’ Since 1981 when deBold et al* reported a natriuretic response to intravenous injection of atria1 extracts in rats, a substantial body of reports on synthesis, release, physiological effects, and its possible role in pathophysiology and pharmacology has emerged.‘,3’5 In contrast, studies on degradation and regional removal of ANF are few. Schiitten et al6 found a significant extraction of ANF in kidney, liver-intestine, and limbs of subjects with minor disorders. Organ extraction of ANF has also been reported in patients with heart disease’ and cirrhosis.839 Recently, Vierhapper et al” found a basal splanchnic uptake of ANF of 8.5 pmol/min in healthy humans. However, no reports have dealt with the effect of food intake on splanchnic disposal of ANF. The present study was undertaken to assess the effect of a meal on splanchnic removal of ANF. We studied persons undergoing a liver vein catheterization, the majority who had disorders of minor degree. MATERIAL AND METHODS Study Population The study comprised three women and three men with a mean age of 62 years (range, 50 to 68 years). All subjects were referred to hepatic vein catheterization i  order to exclude ischemic mesenteric artery disease. This diagnosis was absent in all, and the majority had disorders of minor degree (Table 1). The patient with chronic hepatitis was in a stable stage with normal biochemical liver function tests. Electrocardiogram (ECG), hemoglobin concentration (mean, 9.0 mmol/L; range, 8.2 to 9.5), and serum-sodium concentration (mean, 138 mmol/L; range, 136 to 141) were normal in all. The study was approved by the Ethics Committee for Medical Research in Copenhagen, and all subjects consented to participate in the following investigation. Protocol All subjects were studied in the morning after an overnight fast. Hepatic vein catheterization was performed from the femoral route under local anesthesia nd Ruoroscopiccontrol, as described earlier.” An 6-Fr Gdman catheter with side holes was guided to a large right Metabolism, Vol39, No 5 (May). 1990: pp 553-556 hepatic vein, the tip being approximately 7 cm from the inferior vena cava. A thin indwelling polyethylene catheter was inserted into the femoral artery by the Seldinger technique. Baseline values of ANF concentrations and hepatic blood flow were obtained for 1 hour. Thereafter, a test meal containing 1,000 kcal (83 g carbohydrate, 83 g protein, 37 g lipid) was ingested over 10 minutes and the effect on ANF, hepatic blood flow (HBF), and splanchnic oxygen uptake was recorded for another hour. HBF was determined by the indocyanine green (ICG) constant infusion technique.” In brief, after priming (2 mg), constant infusion of ICG in 5% human albumin preparation into an antecu- bital vein (0.2 mg/min) was maintained by a calibrated pump (Dich, Copenhagen, Denmark) for 130 minutes. After an equilibration period of 30 minutes, blood samples were collected from artery and hepatic vein at an interval of 10 minutes for 100 minutes. ICG was determined spectrophorometrically (Zeiss PMQ-II; Carl Zeiss, Oberkochen, FRG) at 800 nm and 900 nm for turbidity correction. None of the patients had lipemic plasma. Hepatic plasma flow (HPF) was determined as infusion rate, corrected for unsteady arterial concentration, divided by the arterial-hepatic venous concen- tration difference of KG. HBF was obtained from HPF after correction for hematocrit. Oxygen saturation was measured in artery and hepatic vein by OSM, (Radiometer, Copenhagen, Denmark), and splanchnic oxy- gen uptake was determined as HBF - hemoglobin concentration . oxygen difference. Determination of ANF Blood samples were simultaneously collected from the femoral artery and the hepatic vein after discharging catheter-dead space. Five milliliters blood were collected on ice into test tubes containing 2,500 kIU of aprotinin and 250 IU of heparin. Plasma was separated From the Departments of Clinical Physiology and Hepatology. Hvidovre Hospital, University of Copenhagen. Copenhagen, Den- mark; and Department of Medicine II, Klinikum Grosshadern, University of Munich, Munich, FRG. Supported by the John and Birthe Meyer Foundation and the Ebba Celinder Foundation. Address reprint requests to Jens H. Henriksen. MD, Department of Clinical Physiology and Nuclear Medicine, 239, Hvidovre Hospital, DK-2650 Hvidovre, Denmark. @ 1990 by W.B. Saunders Company. 0026-0495/90/3905-0016$3.00/O 553 554 HENRIKSEN, BENDTSEN, AND GERBES Table 1. HBF Rate and Arterial end Hepatic Venous Plasma Concentrations of ANF Before and After Intake of Test Meal in Six Subjects Undergoing Liver Vein Catheterization Baseline After Intake of Meal Subject Age HEF Plasma ANF HBF Plasma ANF pmol/L NO./SeX (Yr) Diagnosis (L/min) (pmol/L; a/hv) (L/min) s&%,* a,,/hv,, a,/‘%, l/M 68 Intercostal neuralgia 1.1s 11.7154 1.68 14.oj5.7 12.7j6.9 14.0/11.7 2/M 50 Dermatomyositis 0.74 23.8112.3 0.95 23.7112.3 18.7/10.8 19.5l12.7 3/F 61 Chronic hepatitis 1.17 14.2/10.6 1.45 17.0/l 1.9 24.0113.9 30.6112.2 4/F 62 Irritable bowel syndrome 0.96 6.010.7 1.44 3.212.9 1.910.6 2.413.8 5/F 68 Irritable bowel syndrome 0.74 6.714.0 0.88 8.1/2.3 6.813.2 9.OJ7.5 6/M 62 Post cholecystectomy pain 1.83 3.111.2 2.64 5.610.6 3.212.5 4.312.3 Mean 62 1.10 10.9/5.7 1.51t 11.9/6.0 1 1.216.3 13.3/8.4$ ‘Numbers denote minutes after intake of test meal. Abbreviation: a/hv, arterylhepatic vein. Significant difference compared with baseline value: thepatic vein, P-c .Ol; $P -c .05. from blood cells immediately by centrifugation at 4°C and frozen (-25%) until assayed. ANF in plasma was determined by radioimmunoassay as de- scribed earlier.‘),‘4 Within- and between-assay coefficients of varia- tion were below 10% and 15%, respectively. Detection limit was 0.5 fmol/mL. Calculations Splanchnic removal rate of ANF (J), fractional extraction ratio (E), and clearance (Cl) were determined by the following equations, where C, and C,, are plasma concentrations of ANF in artery and hepatic vein, respectively: J = HPF + (C, - C,,); E = (C, - C,,)/ C,; and Cl = (C, - C,,) - HPF/C,. Statistical Evaluations Comparisons between paired and grouped differences were per- formed by Student’s paired t test and ANOVA. P < .OS was considered significant. RESULTS Plasma ANF values and HBF are summarized in Table 1. HBF was 1 .I0 k 0.17 L/mm (mean + SEM) and increased significantly in all subjects studied to average 1.51 k 0.26 L/min (P < .Ol) after intake of the test meal. Likewise, splanchnic oxygen uptake increased from 64 + 8.5 to 89 f 12 mL O,/min (P < .Ol). Baseline arterial concentration of ANF (10.9 r 3.1 pmol/L) was close to the normal average, and did not change significantly after meal ingestion. He- patic venous concentration of ANF (5.7 k 2.0 pmol/L) increased to 8.4 r 1.9 pmol/L (P < .05) 60 minutes after meal intake. Arterio-hepatic venous extraction ratios of ANF are shown in Fig 1. Baseline fractional extraction was 0.53 + 0.09, and this value decreased somewhat after the meal, although not statistically significant. No relationship was found between splanchnic ANF and oxygen extraction. Splanchnic clearance of ANF was 347 * 81 mL/min and increased significantly (maximum value, 6 15 + 158 mL/min [P < .05]; average, 441 + 90 mL/min [P < .OS]) after food intake. Hepatic-intestinal removal of ANF was 3.0 + 0.5 pmoL/min before, and reached a maximal value 35 k 5 minutes after ingestion of the meal (7.1 2 2.2 pmol/min; P < .05). Average time course of clearance and removal are shown in Fig 2. DISCUSSION Plasma disappearance of ANF after intravenous infusion is fast, indicating a substantial plasma turnover rate of this peptide.15.16 Other peptides with a fast turnover rate, such as insulin, neurotensin, and vasoactive intestinal polypeptide, have a substantial hepatic degradation,‘7“9 and this may be influenced by food intake.” A few reports6,“**’ have dealt K iC Fig 1. Splanchnic fractional extraction ratio of ANF (ordinate) before (8) end after ingestion of a test meal (~1. Numbers denote minutes after finishing of meal intake. Mean + SEM. 

Splanchnic Removal of Atrial Natriuretic Factor (ANF) in Man

Universität München: Elektronischen Publikationen

Splanchnic Removal of Human Alpha-Atria1 Natriuretic Peptide in Humans: 
Enhancement After Food Intake 
Jens H. Henriksen, Flemming Bendtsen, and Alexander L. Gerbes 
In order to assess the effect of food ingestion on splanchnic disposal of human alpha-atria1 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 [SEMI to 1.51 * 0.26 L/min, P < .Ol). Baseline arterial ANF (10.9 + 3.1 
pmol/L) did not change significantly. In contrast, hepatic venous ANF increased after meal intake (5.7 f 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. Splenchnic clearance of ANF increased from 347 % 90 mL/min to a maximal value of 615 & 
159 mL/min (P < .05). Splanchnic removal of ANF was 3.0 f 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 
splenchnic blood flow, rather than altered fractional extraction of ANF. 
0 1990 by W.B. Saunders Company. 
TRIAL natriuretic factor (human alpha-atria1 natri- A uretic peptide [human ANF 99-1261, abbreviation in 
this report: ANF) is important in the regulation of salt-water 
homeostasis and blood pressure.’ Since 1981 when deBold et 
al* reported a natriuretic response to intravenous injection of 
atria1 extracts in rats, a substantial body of reports on 
synthesis, release, physiological effects, and its possible role 
in pathophysiology and pharmacology has emerged.‘,3’5 In 
contrast, studies on degradation and regional removal of 
ANF are few. Schiitten et al6 found a significant extraction 
of ANF in kidney, liver-intestine, and limbs of subjects with 
minor disorders. Organ extraction of ANF has also been 
reported in patients with heart disease’ and cirrhosis.839 
Recently, Vierhapper et al” found a basal splanchnic uptake 
of ANF of 8.5 pmol/min in healthy humans. However, no 
reports have dealt with the effect of food intake on splanchnic 
disposal of ANF. 
The present study was undertaken to assess the effect of a 
meal on splanchnic removal of ANF. We studied persons 
undergoing a liver vein catheterization, the majority who had 
disorders of minor degree. 
MATERIAL AND METHODS 
Study Population 
The study comprised three women and three men with a mean age 
of 62 years (range, 50 to 68 years). All subjects were referred to 
hepatic vein catheterization in order to exclude ischemic mesenteric 
artery disease. This diagnosis was absent in all, and the majority had 
disorders of minor degree (Table 1). The patient with chronic 
hepatitis was in a stable stage with normal biochemical liver function 
tests. Electrocardiogram (ECG), hemoglobin concentration (mean, 
9.0 mmol/L; range, 8.2 to 9.5), and serum-sodium concentration 
(mean, 138 mmol/L; range, 136 to 141) were normal in all. The 
study was approved by the Ethics Committee for Medical Research 
in Copenhagen, and all subjects consented to participate in the 
following investigation. 
Protocol 
All subjects were studied in the morning after an overnight fast. 
Hepatic vein catheterization was performed from the femoral route 
under local anesthesia and Ruoroscopiccontrol, as described earlier.” 
An 6-Fr Gdman catheter with side holes was guided to a large right 
Metabolism, Vol39, No 5 (May). 1990: pp 553-556 
hepatic vein, the tip being approximately 7 cm from the inferior vena 
cava. A thin indwelling polyethylene catheter was inserted into the 
femoral artery by the Seldinger technique. 
Baseline values of ANF concentrations and hepatic blood flow 
were obtained for 1 hour. Thereafter, a test meal containing 1,000 
kcal (83 g carbohydrate, 83 g protein, 37 g lipid) was ingested over 
10 minutes and the effect on ANF, hepatic blood flow (HBF), and 
splanchnic oxygen uptake was recorded for another hour. 
HBF was determined by the indocyanine green (ICG) constant 
infusion technique.” In brief, after priming (2 mg), constant 
infusion of ICG in 5% human albumin preparation into an antecu- 
bital vein (0.2 mg/min) was maintained by a calibrated pump (Dich, 
Copenhagen, Denmark) for 130 minutes. After an equilibration 
period of 30 minutes, blood samples were collected from artery and 
hepatic vein at an interval of 10 minutes for 100 minutes. ICG was 
determined spectrophorometrically (Zeiss PMQ-II; Carl Zeiss, 
Oberkochen, FRG) at 800 nm and 900 nm for turbidity correction. 
None of the patients had lipemic plasma. Hepatic plasma flow 
(HPF) was determined as infusion rate, corrected for unsteady 
arterial concentration, divided by the arterial-hepatic venous concen- 
tration difference of KG. HBF was obtained from HPF after 
correction for hematocrit. 
Oxygen saturation was measured in artery and hepatic vein by 
OSM, (Radiometer, Copenhagen, Denmark), and splanchnic oxy- 
gen uptake was determined as HBF - hemoglobin concentration . 
oxygen difference. 
Determination of ANF 
Blood samples were simultaneously collected from the femoral 
artery and the hepatic vein after discharging catheter-dead space. 
Five milliliters blood were collected on ice into test tubes containing 
2,500 kIU of aprotinin and 250 IU of heparin. Plasma was separated 
From the Departments of Clinical Physiology and Hepatology. 
Hvidovre Hospital, University of Copenhagen. Copenhagen, Den- 
mark; and Department of Medicine II, Klinikum Grosshadern, 
University of Munich, Munich, FRG. 
Supported by the John and Birthe Meyer Foundation and the 
Ebba Celinder Foundation. 
Address reprint requests to Jens H. Henriksen. MD, Department 
of Clinical Physiology and Nuclear Medicine, 239, Hvidovre 
Hospital, DK-2650 Hvidovre, Denmark. 
@ 1990 by W.B. Saunders Company. 
0026-0495/90/3905-0016$3.00/O 
553 
554 HENRIKSEN, BENDTSEN, AND GERBES 
Table 1. HBF Rate and Arterial end Hepatic Venous Plasma Concentrations of ANF Before and After Intake of Test Meal in Six Subjects 
Undergoing Liver Vein Catheterization 
Baseline 
After Intake of Meal 
Subject Age HEF Plasma ANF HBF 
Plasma ANF pmol/L 
NO./SeX (Yr) Diagnosis (L/min) (pmol/L; a/hv) (L/min) s&%,* a,,/hv,, a,/‘%, 
l/M 68 Intercostal neuralgia 1.1s 11.7154 1.68 14.oj5.7 12.7j6.9 14.0/11.7 
2/M 50 Dermatomyositis 0.74 23.8112.3 0.95 23.7112.3 18.7/10.8 19.5l12.7 
3/F 61 Chronic hepatitis 1.17 14.2/10.6 1.45 17.0/l 1.9 24.0113.9 30.6112.2 
4/F 62 Irritable bowel syndrome 0.96 6.010.7 1.44 3.212.9 1.910.6 2.413.8 
5/F 68 Irritable bowel syndrome 0.74 6.714.0 0.88 8.1/2.3 6.813.2 9.OJ7.5 
6/M 62 Post cholecystectomy pain 1.83 3.111.2 2.64 5.610.6 3.212.5 4.312.3 
Mean 62 1.10 10.9/5.7 1.51t 11.9/6.0 1 1.216.3 13.3/8.4$ 
‘Numbers denote minutes after intake of test meal. 
Abbreviation: a/hv, arterylhepatic vein. 
Significant difference compared with baseline value: thepatic vein, P-c .Ol; $P -c .05. 
from blood cells immediately by centrifugation at 4°C and frozen 
(-25%) until assayed. 
ANF in plasma was determined by radioimmunoassay as de- 
scribed earlier.‘),‘4 Within- and between-assay coefficients of varia- 
tion were below 10% and 15%, respectively. Detection limit was 0.5 
fmol/mL. 
Calculations 
Splanchnic removal rate of ANF (J), fractional extraction ratio 
(E), and clearance (Cl) were determined by the following equations, 
where C, and C,, are plasma concentrations of ANF in artery and 
hepatic vein, respectively: J = HPF + (C, - C,,); E = (C, - C,,)/ 
C,; and Cl = (C, - C,,) - HPF/C,. 
Statistical Evaluations 
Comparisons between paired and grouped differences were per- 
formed by Student’s paired t test and ANOVA. P < .OS was 
considered significant. 
RESULTS 
Plasma ANF values and HBF are summarized in Table 1. 
HBF was 1 .I0 k 0.17 L/mm (mean + SEM) and increased 
significantly in all subjects studied to average 1.51 k 0.26 
L/min (P < .Ol) after intake of the test meal. Likewise, 
splanchnic oxygen uptake increased from 64 + 8.5 to 89 f 12 
mL O,/min (P < .Ol). Baseline arterial concentration of 
ANF (10.9 r 3.1 pmol/L) was close to the normal average, 
and did not change significantly after meal ingestion. He- 
patic venous concentration of ANF (5.7 k 2.0 pmol/L) 
increased to 8.4 r 1.9 pmol/L (P < .05) 60 minutes after 
meal intake. Arterio-hepatic venous extraction ratios of 
ANF are shown in Fig 1. Baseline fractional extraction was 
0.53 + 0.09, and this value decreased somewhat after the 
meal, although not statistically significant. No relationship 
was found between splanchnic ANF and oxygen extraction. 
Splanchnic clearance of ANF was 347 * 81 mL/min and 
increased significantly (maximum value, 6 15 + 158 mL/min 
[P < .05]; average, 441 + 90 mL/min [P < .OS]) after food 
intake. Hepatic-intestinal removal of ANF was 3.0 + 0.5 
pmoL/min before, and reached a maximal value 35 k 5 
minutes after ingestion of the meal (7.1 2 2.2 pmol/min; 
P < .05). Average time course of clearance and removal are 
shown in Fig 2. 
DISCUSSION 
Plasma disappearance of ANF after intravenous infusion 
is fast, indicating a substantial plasma turnover rate of this 
peptide.15.16 Other peptides with a fast turnover rate, such as 
insulin, neurotensin, and vasoactive intestinal polypeptide, 
have a substantial hepatic degradation,‘7“9 and this may be 
influenced by food intake.” A few reports6,“**’ have dealt 
K iC 
Fig 1. Splanchnic fractional extraction ratio of ANF (ordinate) 
before (8) end after ingestion of a test meal (~1. Numbers denote 
minutes after finishing of meal intake. Mean + SEM. 




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Splanchnic Removal of Atrial Natriuretic Factor (ANF) in Man

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