Cardiac C-type natriuretic peptide gene expression and plasma concentrations in neonatal piglets

Background

C-type natriuretic peptide (CNP) is a member of the natriuretic peptide family. Cardiac ANP and BNP expressions are firmly established, whereas CNP expression in the mammalian heart remains controversial. In the present report, we used a porcine model of the neonatal period with high expressions of cardiac ANP and BNP in order to elucidate the cardiac CNP expression profile.

Methods

Plasma and cardiac tissue were obtained from newborn piglets during the first 72 h of life. The chamber-specific CNP mRNA contents were quantified by real-time PCR analysis. The proCNP concentrations in plasma and cardiac tissue extracts were quantified by a porcine-specific radioimmunoassay.

Results

Cardiac CNP mRNA contents (n = 24) were low compared to sites of known expression, where porcine seminal vesicle CNP mRNA contents were 200-fold higher. In addition, plasma proCNP concentrations in the newborn piglets (n = 44) were exceedingly low compared to proANP concentrations (5.3 pmol/L (3.2–8.6) vs. 3438 pmol/L (2790–5418), p < 0.0001). The proCNP concentrations in atrial tissue extracts were barely detectable (≤ 0.06 pmol/g) (n = 2) compared to ventricular proANP (130 pmol/g (101–159)) and atrial proANP (12,303 pmol/g (10,623–15,412)).

Conclusion

Our data show that the heart is not a major source of circulating proCNP in neonatal piglets.