Levels of adrenomedullin and proadrenomedullin N-terminal 20 peptide in myocardium and aorta of spontaneously hypertensive rats and Wistar-Kyoto rats

In this study, we observed the levels of adrenomedullin (ADM) and proadrenomedullin N-terminal 20 peptide (PAMP) in myocardium and aorta of spontaneously hypertensive rats (SHRs) in comparison with Wistar-kyoto (WKY) rats. Contents of ADM and PAMP were measured by radioimmunoassay (RIA) in plasma, myocardium and aorta. The amount of Pro-ADM mRNA of myocardium and aorta was determined by competitive quantitative reverse transcription polymerase chain reaction (RT-PCR). In SHRs the amounts of Pro-ADM mRNA of myocardium and aorta were 66.7% (P<0.01) and 73% (P<0.01) higher than those in WKY rat, respectively. In SHRs, the levels of ADM in plasma, myocardium and aorta were 29%, 76.7% and 79% (all P<0.01) higher than those in WKY rats, respectively. The level of PAMP in SHRs was increased by 42.5% in plasma (P<0.01), 47.2% in myocardium (P<0.0.1) and 27.3% in aorta (P<0.05) compared to WKY rats, respectively. In addition, the ratio of ADM content to PAMP content in SHRs group was increased compared with that in WKY group (2.0+/-0.25 vs 1.64+/-0.3 and 2.2+/-0.18 vs 1.56+/-0.28, in myocardium and aorta, respectively, P<0.01). These results suggest that ProADM gene expression is up-regulated and the increase in ADM and PAMP is different in SHRs. The significance of inconsistency of increase in ADM and PAMP in SHRs needs to be further investigated.PubMed03260-45