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Plasma Atrial NatriUretic Peptide (ANP) fragments proANP(1-30) proANP(31-67) Measurements in Heart Chronic Failure

Cappellin Enrico (1); Meneghetti Martina (1); Lancerin Federica (1); Gatti Rosalba (1); Woloszczuk Wolfgang (3); Teso Enrico (2); Maragno Ildebrando (2); De Palo Elio Franco (1)

(1) Dept of Medical Diagnostic Sciences and Spec. Ter.
Clin. Bioch. Section, Ex Ist. Semeiotica Medica
Univ. of Padua, Padova, Italy.
(2) Cardiology Division, Univ. of Padua, Italy
(3) Ludwig Boltzmann Inst. of Experimental Endocrinology
Univ. of Vienna, Austria

Abstract
Introduction
Objectives
Material and Methods
Results
Discussion
Conclusions

Abstract
Introduction: ProANP(1-30) (NtANP) and proANP(31-67) (mdANP) are circulating fragments of ANP(1-126). NtANP increment in patients with left-ventricular systolic dysfunction, and in chronic heart failure (CHF) subjects has been observed.
Objectives: The mdANP and NtANP in CHF subjects in relation with BNP and the traditional medical parameters, used to follow up the left-ventricular systolic function, were studied.
Material and Methods: 16 CHF patients (age 51.87 ± 13.69 years) and 16 healthy subjects age matched (50.80 ± 5.9 years) were enrolled.
After overnight fasting plasma EDTA was stored at -80°C until assay. NtANP and mdANP enzyme-immunoassays utilised two specific immunoaffinity purified sheep antibodies against NtANP and mdANP respectively. The biotinylated analogues, the peroxidase streptavidin reaction and the TMB colour detection at 450 nm was employed. The crossreactivity of both fragments with C-terminal ANP(99-126) was <1%. The sensitivities were respectively 2.4 and 10 pmol/L. BNP assay was carried out using an IRMA commercial kit (reference value <3.5 pmol/L). Echocardiographic traditional parameters were studied. Mean ± SD are given and the Student’s t-test was used.
Results: Both mdANP and NtANP were higher in CHF patients (1436.60 ± 1153.13 and 2304.88 ± 1531.92 pmol/L) than in healthy subjects (432. C20 ± 262.19, p<0.0001 and 288.49 ± 87.43 pmol/L, p <0.001). BNP in CHF patients was 27.97 ± 34.83 pmol/L.Both mdANP and NtANP demonstrated positive correlations: mdANP and NtANP with BNP p<0.0001, with Left Atrial End-systolic Volume p<0.05. BNP correlated with Left Ventricular mass p<0.03.Conclusion: In conclusion plasma NtANP and mdANP analysis are useful laboratory markers in CHF patients investigation and follow up.

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Introduction:

ANP is secreted by atrial myocytes as a 126 aminoacid molecule and cleaved in different fragments, namely proANP(1-30) (NtANP), proANP(31-67) (mdANP), proANP(79-98) and the active one ANP(99-126) (ER Levin, 1998. The New England Journal of Medicine 339(5):321-8). It has been observed that NtANP levels increase in patients with left-ventricular systolic dysfunction, such as chronic heart failure (CHF) subjects(Azizi C,1996 J Endocrinology 148: 51-57).

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Objectives:

We studied the mdANP and NtANP in CHF subjects in relation with BNP and the traditional medical parameters, used to follow up the left-ventricular systolic function. Our aim was also to study if pro ANP fragments can be proposed as useful parameters of left ventricular function in heart chronic failure natural history.

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Material and Methods:

16 CHF patients (age 51.87 ± 13.69 years) and 16 healthy subjects age matched (50.80 ± 5.92 years) were enrolled in the study.
After overnight fasting, plasma EDTA was stored at -80°C until assay. NtANP and mdANP enzyme-immunoassays utilised two specific immunoaffinity purified sheep antibodies against NtANP and mdANP respectively. The biotinylated analogues, the peroxidase streptavidin reaction and the TMB colour detection at 450 nm were employed. The crossreactivity of both fragments with C-terminal ANP(99-126) was <1%. The sensitivities were respectively 2.4 and 10 pmol/L, the precision 4% and 5%, and the recovery test 106% and 102%. BNP assay was carried out using an IRMA commercial kit (reference value <3.5 pmol/L). Echocardiographic traditional parameters were studied. Results are given as mean ± SD and the Student’s t-test was used for statistical analysis.

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Results:

Both mdANP and NtANP were higher in CHF patients (1436.60 ± 1153.13 and 2304.88 ± 1531.92 pmol/L) than in healthy subjects (432.20 ± 262.19, p<0.0001 and 288.49 ± 87.43 pmol/L, p <0.001), see table 1 and 2. BNP in CHF patients was 27.97 ± 34.83 pmol/L.Both mdANP and NtANP demonstrated positive correlations: mdANP and NtANP with BNP p<0.0001, with Left Atrial End-systolic Volume p<0.05. BNP correlated with Left Ventricular mass p<0.03.

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Discussion:

This results show that proANP fragments significantly increase in CHF than in control subject. Taking into account Klinge observations, NtANP and also mdANP could be employed as biochemical markers of left ventricular dysfunction in asymptomatic subjects with risk factors for chronic heart failure.
Furthermore they could be used, in addiction or in substitution of echocardiography, during follow up of the patient after the diagnosis of CHF.

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Conclusions:

In conclusion present findings demonstrate that plasma NtANP and mdANP analysis are useful laboratory markers in CHF patients investigation and follow up.

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Questions, contributions and commentaries to the Authors: send an e-mail message (up to 15 lines, without attachments) to heartfail-pcvc@pcvc.sminter.com.ar , written either in English, Spanish, or Portuguese.

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Update
Mar/05/2000


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