Hormonal and cardiorenal responses to acute saline loading in mild congestive heart failure--the effect of angiotensin converting enzyme inhibition

Neuroendocrine and renal effects of intravascular volume expansion in compensated heart failure

To examine if the neuroendocrine link between volume sensing and renal function is preserved in compensated chronic heart failure [HF, ejection fraction 0.29 +/- 0.03 (mean +/- SE)] we tested the hypothesis that intravascular and central blood volume expansion by 3 h of water immersion (WI) elicits a natriuresis. In HF, WI suppressed ANG II and aldosterone (Aldo) concentrations, increased the release of atrial natriuretic peptide (ANP), and elicited a natriuresis (P < 0.05 for all) compared with seated control. Compared with control subjects (n = 9), ANG II, Aldo, and ANP concentrations were increased (P < 0.05) in HF, whereas absolute and fractional sodium excretion rates were attenuated [47 +/- 16 vs. 88 +/- 15 micromol/min and 0.42 +/- 0.18 vs. 0.68 +/- 0.12% (mean +/- SE), respectively, both P < 0.05]. When ANG II and Aldo concentrations were further suppressed (P < 0.05) during WI in HF (by sustained angiotensin-converting enzyme inhibitor therapy, n = 9) absolute and fractional sodium excretion increased (P < 0.05) to the level of control subjects (108 +/- 34 micromol/min and 0.70 +/- 0.23%, respectively). Renal free water clearance increased during WI in control subjects but not in HF, albeit plasma vasopressin concentrations were similar in the two groups. In conclusion, the neuroendocrine link between volume sensing and renal sodium excretion is preserved in compensated HF. The natriuresis of WI is, however, modulated by the prevailing ANG II and Aldo concentrations. In contrast, renal free water clearance is attenuated in response to volume expansion in compensated HF despite normalized plasma AVP concentrations.

Systemic and renal effects of atrial natriuretic peptide in patients with heart failure treated with angiotensin-converting enzyme inhibitor or in acute saline solution loading

BACKGROUND

Our purpose was to study the effects of atrial natriuretic peptide (ANP) on cardiorenal functions when it is used to manage patients with heart failure who are receiving an angiotensin-converting enzyme inhibitor (ACEi) or in acute saline solution loading.

METHODS

Seventeen patients with mild to moderate heart failure were entered into protocol 1 or 2. Protocol 1 was ANP (30 ng/kg/min) infused before and after treatment with ACEi (n = 9). Protocol 2 was acute saline loading with or without coadministration of ANP (n = 8). In both protocols cardiorenal hemodynamics and urinary sodium excretion were assessed before and after each intervention.

RESULTS

Protocol 1: Although ANP infusion significantly increased urinary sodium excretion to a similar extent before and after ACEi treatment, the infusion increased the glomerular filtration rate (75 +/- 16 --> 82 +/- 15 mL/min, P <.05) and renal blood flow (390 +/- 123 --> 438 +/- 140 mL/min, P <.05) only before ACEi treatment. Protocol 2: Acute saline solution loading decreased plasma renin activity (P <.05) but did not affect ANP level. Coadministration of ANP with saline solution load enhanced the increase of urinary sodium excretion (75% +/- 34% increase) compared with the acute saline solution load alone (49% +/- 33% increase) (P <.05) but had no affect on renal hemodynamics.

CONCLUSIONS

When ANP is used in patients with mild to moderate heart failure who are on combined ACEi treatment or in acute saline solution loading, the vasodilatory effect of ANP is blunted while the natriuretic effect of ANP is preserved. The renin-angiotensin system seems to modulate the vasodilatory effect of ANP.

Effects of oral administration of L-arginine on renal function in patients with heart failure

OBJECTIVES

Although the beneficial effects of L-arginine on systemic haemodynamics have been reported in patients with heart failure, its effect on renal function has not been examined. We evaluated the effects of oral administration of L-arginine on renal haemodynamics, sodium and water handling, and various hormonal factors in patients with chronic heart failure.

SUBJECTS AND METHODS

A double-blind crossover trial was performed in 17 patients with chronic congestive heart failure (NYHA II-III, 56 +/- 12 years of age) who were randomly assigned to receive oral L-arginine (15 g/day) and placebo or placebo and arginine sequentially for 5 days each. Twenty-four hour creatinine clearance (Ccr), and 24-h urinary cyclic guanosine 5-monophosphate (GMP) excretion were determined. Saline loading was performed on day 5 of each treatment Renal blood flow, glomerular filtration rate (GFR), and urinary sodium excretion rate (UNa) were assessed before and after saline loading.

RESULTS

Twenty-four hour GMP excretion (1.4 +/- 1.1 versus 0.8 +/- 0.5 micromol/day, P < 0.01) and Ccr (150 +/- 43 versus 125 +/- 42 ml/min, P < 0.05) were higher and plasma endothelin level (2.5 +/- 0.6 versus 3.1 +/- 0.8 pg/ml, P < 0.05) was lower with L-arginine treatment compared to placebo treatment In addition, the relative increase of UNa and GFR after saline loading were significantly higher in L-arginine treatment (UNa, 47 +/- 12%; GFR, 44 +/- 31%) than in placebo treatment (UNa, 34 +/- 9%; GFR, 22 +/- 29%) (P < 0.05).

CONCLUSIONS

Oral administration of L-arginine has beneficial effects on glomerular filtration rate, natriuresis, and plasma endothelin level in patients with chronic congestive heart failure.