Effects of high dose atrial natriuretic peptide on renal haemodynamics, sodium handling and hormones in cirrhotic patients with and without ascites

Effects and safety of natriuretic peptides as treatment of cirrhotic ascites: A systematic review and meta-analysis

BACKGROUND

Natriuretic peptides are involved in the cascade of pathophysiological events occurring in liver cirrhosis, counterbalancing vasoconstriction and anti-natriuretic factors. The effects of natriuretic peptides as treatment of cirrhotic ascites have been investigated only in small studies, and definitive results are lacking.

AIM

To examine the effects and safety of natriuretic peptides in cirrhosis patients with ascites.

METHODS

We searched MEDLINE, Web of Science, Scopus, Cochrane Library and Embase for all available studies applying intravenous administration of any natriuretic peptide to patients suffering from cirrhotic ascites. Inclusion was not limited by treatment duration or dose, or by follow-up duration. Both randomised controlled trials and non-randomised studies were eligible for inclusion. The primary outcome was change in renal sodium excretion. Secondary outcomes included safety measures and changes in renal water excretion, plasma aldosterone concentration, and plasma renin activity.

RESULTS

Twenty-two studies were included. Atrial natriuretic peptide (ANP) was the only intensively studied treatment. Sodium excretion increased in response to continuous ANP infusion and was more pronounced when infusion rates of > 30 ng/kg/min were administered compared with ≤ 30 ng/kg/min (P < 0.01). Moreover, natriuresis was significantly higher in study subgroups with mild/moderate ascites compared with moderate/severe and refractory ascites (P < 0.01). ANP infusions increased renal water excretion, although without reaching a statistically significant dose-response gradient. Plasma aldosterone concentration and plasma renin activity were significantly lower at baseline in study subgroups achieving a negative sodium balance in response to an ANP administration compared with treatment non-responders (P < 0.01). Blood pressure decreases occurred less frequently when ANP doses ≤ 30 ng/kg/min were applied. The quality of evidence for a natriuretic response to ANP was low, mainly due to small sample sizes and considerable between-study heterogeneity. Data were sparse for the other natriuretic peptides; B-type natriuretic peptide and urodilatin.

CONCLUSION

Intravenous ANP infusions increase sodium excretion in patients with cirrhotic ascites. Continuous infusion rates > 30 ng/kg/min are the most effective. However, safety increases with infusion rates ≤ 30 ng/kg/min.

Nitric oxide synthase inhibition does not improve renal function in cirrhotic patients with ascites

OBJECTIVES

Based mainly on animal experiments, nitric oxide (NO) has been proposed to account for the peripheral arterial vasodilation and hyperdynamic circulation in liver cirrhosis. The aim of this study was to clarify whether a reduction of NO synthesis would ameliorate the circulatory and renal dysfunction in decompensated cirrhotic patients.

METHODS

The effects of N(G)-monomethyl-L-arginine-acetate (L-NMMA), an NO synthesis inhibitor, were studied. After a 60-min basal period, a total of 10 patients received increasing doses of L-NMMA, five patients (Low) received 12.5, 25, and 50 microg/kg/min, and five patients (High) received 25, 50, and 100 microg/kg/min as a constant infusion during 3 h, followed by a postinfusion period. Five patients (Placebo) received saline infusions only. Glomerular filtration rate and renal plasma flow were measured by clearance techniques with (99m)Tc-diethylenetriamine-pentaacetate and (131)I-Hippuran.

RESULTS

L-NMMA infusion resulted in an increased blood pressure, decreased heart rate, and dose-dependent suppression of renin of up to 42.1 +/- 7.1% (p < 0.01) and angiotensin II of up to 39.9 +/- 9.6%, (p < 0.01) levels. Sodium and water excretion were not improved, most likely because of a reduction in renal blood flow of up to 29.1 +/- 8.1% (p < 0.01).

CONCLUSION

Despite a partial correction of the hyperdynamic circulation, inhibition of NO synthesis does not improve sodium and water excretion in decompensated cirrhosis, probably because of an accompanying decrease in renal plasma flow. Intrarenal NO synthesis may be important for maintaining intrarenal hemodynamics in decompensated cirrhotic patients.

The organ extraction and splanchnic haemodynamic effects of octreotide in cirrhotic patients

BACKGROUND

Intravenous octreotide is an established treatment of oesophageal variceal haemorrhage in the cirrhotic patient.

AIM

To examine the organ extraction and splanchnic haemodynamic effects of octreotide in cirrhotic patients with portal hypertension.

METHODS

Thirteen patients with cirrhosis had hepatic venous catheterization performed. Hepatic venous pressure gradient (HVPG), indocyanine green (ICG) clearance and hepatic blood flow (HBF) were determined in the basal state and during 60 min of octreotide infusion by bolus injection (0.75 microg/kg) followed by continuous infusion of 0.75 microg/kg x h. Blood samples were simultaneously drawn from the femoral artery and the hepatic and renal veins.

RESULTS

The extraction fraction of octreotide in the liver was 0.05 (-0.01 - 0.14) (median (interquartile range)) and in the kidneys 0.16 (-0.06 - 0.35). The extraction fraction ratio (E(liver)/E(kidney)) was 0.69 (-0.20 - 1.06). Hepatic clearance was 47 mL/min (3-88) (n = 11). No correlations were found between liver biochemistry or galactose elimination capacity (GEC; a metabolic measure of liver function) and renal extraction fraction or liver clearance. Octreotide had no effect on HVPG or wedged hepatic venous pressure although free hepatic venous pressure increased during octreotide infusion: 6 mmHg (5-9) vs. 7 mmHg (6-10) (P = 0.02). No effect on HBF was observed while ICG clearance decreased significantly.

CONCLUSIONS

Octreotide is extracted in cirrhotic patients by both the liver and the kidney, the latter being the most important organ of elimination. Octreotide decreases liver metabolic activity determined by the ICG clearance technique, but no significant effects of octreotide on HVPG or HBF could be demonstrated.

Inhibitory effect of aldosterone on the natriuretic response to atrial natriuretic peptide in hypocapnic rats

1. Previous studies have shown that acute hypocapnia blunts the natriuretic effect of atrial natriuretic peptide (ANP) independently of the renal nerves and that the effect of ANP is restored by total adrenalectomy. We investigated the natriuretic response to ANP in potassium canrenoate (aldosterone receptor antagonist)-treated rats to clarify whether aldosterone contributes to the attenuated natriuretic response to ANP during hypocapnia. 2. Wistar rats, challenged with either canrenoate or saline vehicle, were infused with 10 micrograms/kg per h ANP during acute hypocapnia achieved by mechanical ventilation. 3. In saline-treated hypocapnic rats, ANP infusion failed to increase the fractional excretion of sodium (FENa) (from 3.49 +/- 0.26 to 5.03 +/- 0.42%, respectively; n = 6) which was similar to values for time control rats (from 3.00 +/- 0.61 to 4.41 +/- 0.68%; n = 6). The hyporesponsiveness to ANP during hypocapnia was also evident when the FENa was compared with that of normocapnic rats (from 3.92 +/- 0.69 to 7.87 +/- 0.45%; P < 0.05; n = 6). In canrenoate-treated rats, ANP infusion caused greater increases in sodium excretion (FENA from 3.05 +/- 0.71 to 7.21 +/- 0.45%; P < 0.05; n = 8) than saline infusion (FENA from 4.16 +/- 1.11 to 5.47 +/- 0.66%; n = 6), despite the hypocapnia. The increase in FENA after ANP infusion during hypocapnia (4.16 +/- 0.86%) was similar to the increase seen during normocapnia (3.89 +/- 0.86%; n = 9). 4.

IN CONCLUSION

(i) acute hypocapnia blunts the natriuretic effects of ANP; and (ii) this attenuation is restored by potassium canrenoate treatment. The data suggest that aldosterone plays an important role by limiting the renal actions of ANP during acute hypocapnia.

Adrenalectomy overcomes the blunted natriuretic response to atrial natriuretic peptide during hypocapnia in rats

1. Hypocapnia has been shown to blunt the natriuretic effect of atrial natriuretic peptide (ANP) independently of the renal nerves. In order to examine whether the adrenal glands are a limiting factor for the natriuretic effect of ANP, we evaluated the natriuretic responses of adrenalectomized rats to ANP infusion during hypocapnia. 2. Rats subjected to total adrenalectomy (ADX) or sham-operation (sham) were divided into hypocapnic and normocapnic groups depending on their arterial PCO2 levels. 3. In sham rats, ANP infusion at a rate of 12 micrograms/kg per h resulted in a smaller increase in the fractional excretion of sodium during hypocapnia (mean +/- SEM: 1.02 +/- 0.40%, n = 10) than normocapnia (3.95 +/- 0.64%, n = 9; P < 0.001). The level of fractional excretion of sodium with ANP infusion during hypocapnia was not significantly different from the level in saline-infused hypocapnic sham rats (0.93 +/- 0.62%, n = 10). In hypocapnic ADX rats (n = 11), ANP induced greater increases in the fractional excretion of sodium (5.59 +/- 1.35%) than did saline infusion (1.04 +/- 1.02%, n = 10; P < 0.002). In the absence of adrenal glands, the magnitude of natriuresis after ANP infusion during hypocapnia and normocapnia (3.32 +/- 1.07%, n = 9) were the same. 4. We conclude that the natriuretic effect of ANP is blunted during hypocapnia in the presence, but not in the absence, of adrenal glands. Our data suggest that the adrenal glands have an important role in limiting the natriuretic effect of ANP.