NPR-B, the C-type natriuretic peptide specific receptor, is the predominant biological receptor in mouse and pig myocardial tissue.
OBJECTIVE
The increased myocardial production and the elevated plasma concentrations of C-type natriuretic peptide (CNP) in heart failure patients suggest its involvement in pathophysiological cardiac remodeling. The cardiovascular action of CNP seems to be mainly mediated by natriuretic peptide receptor (NPR)-B but the importance of CNP/NPR-B signaling in heart is not yet well characterized. The aim of this study was to assess the cardiac mRNA expression of CNP and NPR-B together with those of BNP and NPR-A in order to evaluate the relative importance of these peptides and of their receptors in cardiovascular system.


METHODS
The expression of mRNA coding for CNP, NPR-B, BNP and NPR-A was investigated in myocardial tissue (BALB/c mice, N=5) by use of RT-PCR. NPR-A and NPR-B expression were also evaluated in left ventricle of male adult minipigs without (N=5) and with pacing-induced heart failure (HF, N=5).


RESULTS
The proposed method allowed to detect the expression of mRNA coding for CNP and NPR-B in myocardial tissue confirming the presence of these effectors in the heart. These data also indicate that CNP mRNA expression is lower with respect to that of BNP (CNP/GAPDH= 0.117+/-0.035 vs. BNP/GAPDH=0.247+/-0.066) and that NPR-B is the predominant subtype receptor in the heart (Mouse: NPR-A/GAPDH=0.244+/- 0.028; NPR-B/GAPDH=0.657+/-0.022; p=0.0008; Pig: NPR-A/GAPDH=3.06+/-1.75, NPR-B/GAPDH= 14.3+/-3.6, p=0.0028; HF Pig: NPR-A/GAPDH= 4.29+/-0.93, NPR-B/GAPDH=7.9+/-1.1, p=0.0043).


CONCLUSIONS
In the present study, we provided the first evidence of a higher mRNA expression in cardiac tissue of NPR-B with respect to NPR-A indicating that CNP specific receptor (NPR-B) is the predominant biological receptor in mouse and pig myocardial tissue.
Del Ry
S
S
CNR Institute of Clinical Physiology, Laboratory of Cardiovascular Biochemistry, Via Giuseppe Moruzzi 1, Pisa, Italy. delry@ifc.cnr.it
Cabiati
M
M
Lionetti
V
V
Giannessi
D
D
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D004195:Disease Models, Animal; D006168:Guinea Pigs; D006333:Heart Failure / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009206:Myocardium / Q000378:metabolism*; D020098:Natriuretic Peptide, C-Type / Q000096:biosynthesis*; D011237:Predictive Value of Tests; D012333:RNA, Messenger / Q000378:metabolism; D017461:Receptors, Atrial Natriuretic Factor / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D000099242:Atrial Natriuretic Factor Receptor B
D015415:Biomarkers; D020098:Natriuretic Peptide, C-Type; D012333:RNA, Messenger; D017461:Receptors, Atrial Natriuretic Factor; D000099242:Atrial Natriuretic Factor Receptor B