Effects of enalaprilat sodium on plasma NTproANP and NTproBNP levels in healthy volunteers

Background

The N-terminal prohormones of the A-type and B-type natriuretic peptides (NTproANP and NTproBNP) are increasingly used as humoral markers for myocardial dysfunction in various clinical settings [1]. No data are available on the effects of angiotensin-converting-enzyme inhibition (ACE-I) on the plasma levels of these hormones.

Materials and methods

Ten healthy males were cross-over and double-blind treated with 20 mg enalaprilat sodium or placebo (t0) following 7 days on a sodium enriched-diet and an induction period of 4 days with increasing doses of enalapril. After 4 hours (t4) 15 ml/kg NaCl 0.9% was infused over 60 min. Hemodynamics were determined and blood was sampled at t0, t4, t5, t6, t8, and t10 hours. NTproANP and NTproBNP were determined by radio-luminescence and electrochemoluminescence immunoassays, respectively. Data were analyzed as raw data and as relative changes in comparison with baseline levels.

Results

Arterial blood pressure was significantly lower after enalapril treatment during the fourth day of induction and during t0–t8 in comparison with control. Raw NT-proANP levels did not change throughout the observation period; relative NTproANP levels showed a short-lasting increase from t4 to t6 during control and ACE-I (after sodium loading). Raw and relative plasma NTproBNP levels increased from t0 to t10 during placebo and enalapril (P < 0.001). No between-group differences were observed in raw NTproBNP levels, while relative NTproBNP levels were significantly higher after ACE-I in comparison with control at t4 and t5 (Fig. 1).

Figure 1

Conclusion

This suggests that ACE-I does not affect baseline and stimulated plasma NTproANP levels but augments the reactivity of the BNP system in sodium-loaded healthy individuals. ACE-I may thus interfere with NTproBNP determinations in sodium-retaining states.