Expression of B-type natriuretic peptide forms in ischemic human hearts.
ABSTRACT This study sought to determine pro-B-type natriuretic peptide (proBNP), BNP, N-terminal proBNP (NT-proBNP) and GATA-4 in the same cardiac tissue, the correlation among them, and the influence of ischemic etiology on their levels.
Protein levels were analyzed by Western blot techniques and mRNA expression was quantified by quantitative real-time polymerase chain reaction (RT-PCR) in a total of 33 human samples from ischemic (ICM), and control hearts.
Tissue protein level of proBNP is 1.5- and 12-fold higher than BNP or NT-proBNP respectively (p<0.0001), and BNP protein level was 8-fold higher than that of NT-proBNP (p<0.0001) in ICM hearts. Furthermore, proBNP mRNA expression was also increased in ICM (4-fold) compared to control hearts (p<0.05), but there was not a significant increase in GATA-4 mRNA. Then, tissue NP forms showed a high correlation among them (proBNP vs. BNP r=0.74, p<0.0001; proBNP vs. NT-proBNP r=0.43, p=0.03; and BNP vs. NT-proBNP r=0.61, p=0.001, respectively). Furthermore, GATA-4 with proBNP (r=0.536, p=0.007) and BNP (r=0.610, p=0.001) in ischemic samples. Finally, we found that proBNP, BNP, NT-proBNP and GATA-4 were increased in our ICM hearts (by 14%, p=0.004; 46%, p=0.024, 33%, p=0.002, and 49%, p=0.026, respectively) compared with controls.
This study shows higher protein level of proBNP in human hearts than of BNP and NT-proBNP, increased proBNP mRNA expression in ICM samples, and a good correlation among tissue natriuretic peptide and GATA-4. Finally, ICM shows a high tissue protein level of proBNP, BNP, NT-proBNP and GATA-4.