Objective: To explore the production of ADM, changes and significance of adrenomedullin (ADM) mRNA and ADM receptor system-calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) mRNA in calcified myocardium and aorta of rats.
Methods: Contents of ADM in plasma, myocardium and vessel were measured by radioimmunoassay (RIA). The amount of ADM, CRLR and RAMPs mRNA was determined by semi-quantitative RT-PCR.
Results: The contents of calcium in calcified myocardium and aorta were increased by 342% and 606% (all P<0.01), respectively, and alkaline phosphatase activities in calcified myocardium and vessel were increased by 66.5% and 82.7% (all P<0.01), respectively, compared with the control. Contents of ADM in plasma, myocardium and aorta were increased by 58 % (P<0.01), 14.3%(P<0.01) and 27.8%(P<0.05). Furthermore, it was found that the levels of ADM, CRLR and RAMP2 mRNA in calcified myocardium were elevated by 90.6% 157.5% and 119.6%(all P<0.01), respectively, but RAMP3 mRNA was decreased by 14.1 %(P<0.01). The levels of ADM, CRLR, RAMP2 and RAMP3 mRNA in calcified aorta were elevated by 37.7%(P<0.01), 41.4%(P<0.01),60.1%(P<0.05) and 13%(P<0.01) respectively, compared with the control. The elevated levels of CRLR, RAMP2 or RAMP3 mRNA were positively correlated with up regulations of ADM mRNA in calcified myocardium and aorta.
Conclusion: Calcified myocardium and aorta may generate an increased amount of ADM, different alterations of gene expressions of ADM and its receptor system. These RESULTS suggest that ADM and its receptor system might participate in the regulation of calcification in heart and vessel.