Adrenomedullin2 in SHR

Background Adrenomedullin-2(ADM2)is a novel peptide of calcitonin(CT)/calcitonin gene-related peptide(CGRP)super family,which was reported by Japanese scholar in February 2004.In November 2003,Roh et al of Stanford University discovered intermedin(IMD).They were regarded as identical substance because of their same nucleotid and amino acid sequence.ADM,CGRP,CT andIAPP(islet amyloid poly peptide)belong to CGRP super family.Recently reserch have suggested that ADM2 was involved in cardiovascular regulation.Objective To compare the difference of adrenomedullin2(ADM2)or intermedin(IMD)content and its genetic expression in plasma and tissue between SHRs and Wistar Kyoto(WKY)rats.The relationship between ADM2 in plasma,blood pressure and heart mass/body mass(HM/BM)are explored.Methods Eight male,11-week-old SHRs were chosen as experiment group,with 8 male WKY rats of matched age as controls.Plasma and tissue ADM2 were determined by radioimmunoassay.Myocardium and aortic mRNA expression of ADM2 were determined by RT-PCR.Blood pressure and heart function were determined by cardiac catheterization.Results Comparing with the WKY rats,plasma ADM2(317.2±25.2 vs 211.4±15.0 ng/L,P0.01),ADM2 in myocardium(293.6±34.7 vs 200.4±21.6 ng/g,P0.05)and in aorta(1009.0±50.1 vs 763.8±35.0 ng/g,P0.01)of SHRs were significantly increased.mRNA expression of ADM2 in tissue of SHRs were also higher than those in WKY rats(+76.1% in myocardium,P0.05;+71.11% in aorta,P0.01).Plasma ADM2 was negatively correlated with SBP(r=-0.822,P0.05)in SHR.Conclusion These data suggest that ADM2 as a cardiovascular active peptide may involve in regulation of blood presurre and myocardial protection.