The purpose of the present study was to explore the expression changes of intermedin/adrenomedullin 2 (IMD/ADM2), a novel small molecular bioactive peptide, and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMP1, RAMP2, RAMP3) in the right ventricle of rats with chronic hypoxia-induced pulmonary hypertension. Twenty male Sprague-Dawley rats were randomly divided into 4-week hypoxia group and normal control group (each n=10). The rats in hypoxia group were placed in an isobaric hypoxic chamber, in which O(2) content was maintained at 9%-11% by delivering N(2), and CO(2) content was maintained at <3% for 4 weeks (8 h/d, 6 d/week). The rats in the control group were housed in room air. The protein levels of IMD/ADM2 and adrenomedullin (ADM) in blood plasma and right ventricular tissue were measured by radioimmunoassay. The mRNA expressions of IMD/ADM2, ADM and their receptors CRLR, RAMP1, RAMP2, RAMP3 in right ventricular tissue were determined by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the ratio of right ventricle weight to left ventricle plus septum weight [RV/(LV+S)] and mean pulmonary arterial pressure (mPAP) were higher in hypoxia group than those in the control group (all P<0.01), suggesting that the rat model of pulmonary hypertension was successfully established. However, the mean carotid arterial pressure (mCAP) between the two groups had no significant difference. Compared with that in the control group, ADM contents in plasma and right ventricular tissue in hypoxia group increased by 1.26 and 1.68 folds (all P<0.01), respectively. Likewise, IMD/ADM2 contents in blood plasma and right ventricular tissue in hypoxia group increased by 0.90 and 1.19 folds (P<0.01), respectively, compared with that in the control group. The data of RT-PCR showed that mRNA levels of ADM, IMD/ADM2 and RAMP2 in hypoxia group increased by 155.1% (P<0.01), 80.9% (P<0.01) and 52.9% (P<0.05), respectively, compared with those in the control group. There were no significant differences in mRNA expressions of CRLR, RAMP1 and RAMP3 between the two groups (all P>0.05). Taken together, the results show that the level of IMD/ADM2 increases in the rats with chronic hypoxia-induced pulmonary hypertension.
Adrenomedullin ; metabolism ; Animals ; Calcitonin Receptor-Like Protein ; metabolism ; Heart Ventricles ; metabolism ; Hypertension, Pulmonary ; etiology ; metabolism ; physiopathology ; Hypoxia ; complications ; Male ; Neuropeptides ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor Activity-Modifying Proteins ; metabolism

OBJECTIVEReceptor activity-modifying proteins (RAMPs) determine the ligand specificity of the calcitonin receptor-like receptor (CRLR); co-expression of RAMP1 and CRLR results in a calcitonin gene related peptide (CGRP) receptor, whereas the association of RAMP2 or RAMP3 with CRLR gives an adrenomedullin(ADM) receptor. As CGRP and ADM may play a beneficial role in heart failure, this study aimed at the question whether RAMPs mRNAs are changed in heart failure.

METHODSSemi-quantitative reverse transcription-PCR (RT-PCR) was used to detect and quantify the mRNAs of RAMP1 and RAMP3 in the atria of heart failing patients.

RESULTSIt was found that the expressions of RAMP1, RAMP2 and RAMP3 mRNAs increased with the worsening of heart function, but the expressions of RAMP1 and RAMP2 mRNA decreased at level IV of heart failure.

CONCLUSIONThe above results demonstrated in the atria of heart failure patients an up-regulation of CGRP receptor by an increase of RAMP1 in association with CRLR and an up-regulation of ADM receptor by an increase of RAMP2 expression in association with CRLR, thus suggesting that CGRP and ADM receptors be playing a functional role in compensating the chronic heart failure in human.

Adult ; Calcitonin Receptor-Like Protein ; Female ; Heart Atria ; metabolism ; Heart Failure ; genetics ; physiopathology ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; physiology ; Male ; Membrane Proteins ; genetics ; physiology ; Receptor Activity-Modifying Protein 1 ; Receptor Activity-Modifying Protein 2 ; Receptor Activity-Modifying Protein 3 ; Receptor Activity-Modifying Proteins ; Receptors, Adrenomedullin ; Receptors, Calcitonin ; genetics ; physiology ; Receptors, Calcitonin Gene-Related Peptide ; genetics ; physiology ; Receptors, Peptide ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction

Soluble suppression of tumorigenicity 2 (sST2) has emerged as a biomarker of cardiac stretch or remodeling, and has demonstrated a role in acutely decompensated heart failure. However, its role in sepsis-induced cardiac dysfunction is still unknown. We explored whether sST2 serum concentration reflects either systolic or diastolic dysfunction as measured by Doppler echocardiography. In a total of 127 patients with sepsis, correlations between sST2 and blood pressure, left ventricular (LV) ejection fraction, LV diastolic filling (ratio of early transmitral flow velocity to early diastolic mitral annulus velocity), and resting pulmonary arterial pressure were evaluated. Correlations between sST2 and other sepsis biomarkers (high-sensitivity C-reactive protein [hs-CRP] and procalcitonin) were also examined. sST2 showed a moderate correlation with mean arterial pressure (r=-0.3499) but no correlation with LV ejection fraction, diastolic filling, or resting pulmonary hypertension. It showed moderate correlations with hs-CRP and procalcitonin (r=0.2608 and r=0.3829, respectively). sST2 might have a role as a biomarker of shock or inflammation, but it cannot reflect echocardiographic findings of LV ejection fraction or diastolic filling in sepsis.
Aged ; Aged, 80 and over ; Biomarkers/blood ; Blood Pressure/physiology ; C-Reactive Protein/analysis ; Calcitonin/blood ; Echocardiography, Doppler ; Female ; Humans ; Interleukin-1 Receptor-Like 1 Protein/*blood ; Male ; Middle Aged ; Sepsis/diagnostic imaging/metabolism/*physiopathology ; Ventricular Function, Left/physiology

OBJECTIVE: To investigate the effect and potential mechanism of intermedin (IMD) in acute cardiac ischemic injury and to provide a new approach for exploring mechanism of sudden cardiac death. METHODS: Seventy-two healthy male rats were randomly divided into 3 groups: control, ischemic and the IMD-treated group. The activity of lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) in heart blood were tested by enzyme chemistry method. The mRNA changes of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) in cardiac were measured by real-time PCR analysis. Myocardial cyclic adenosine monophosphate (cAMP) content was determined by enzyme linked immunosorbent assay (ELISA). Apoptosis related factors Bcl-2 and Bax were detected by immunohistochemistry. RESULTS: Comparing with the control group, LDH and MDA activity of ischemic group in heart blood increased and SOD activity decreased. The concentration of cAMP increased in ventricular muscle, Bcl-2 and Bax proteins expression ratio level decreased. The intravenation of IMD decreased the level of increased activity of LDH and MDA, and lessened the level of decreased activity of SOD. The mRNA expression of CRLR and RAMPs obviously increased in ventricular muscle. CONCLUSION The protective effect of IMD against myocardial ischemic injury could be caused by decreasing the oxidative stress of ischemia and inhibiting the myocardial apoptosis.
Adrenomedullin/pharmacology* ; Animals ; Apoptosis/drug effects* ; Calcitonin Receptor-Like Protein/metabolism* ; Cardiotonic Agents/pharmacology* ; Cyclic AMP/metabolism* ; Disease Models, Animal ; L-Lactate Dehydrogenase/metabolism* ; Male ; Malondialdehyde/metabolism* ; Myocardial Ischemia/pathology* ; Myocardium/pathology* ; Neuropeptides/pharmacology* ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; RNA, Messenger/metabolism* ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction ; Receptor Activity-Modifying Proteins/metabolism* ; Superoxide Dismutase/metabolism*

OBJECTIVETo observe the localization of adrenomedullin (AM) in rat kidney tissue and its inhibitory effect on the growth of cultured rat mesangial cells (MsC).

METHODSA monoclonal antibody against AM developed by our laboratory was used to detect the localization of AM protein in rat kidney tissue by avidin-biotin complex immunohistochemistry. The expressions of AM and its receptor CRLR mRNA on cultured glomerular epithelial cells (GEC) and MsC were investigated by Northern blot assay, and the possible effect of AM secreted by GEC on MsC proliferation was observed using [3H]thymidine incorporation as an index.

RESULTSA specific monoclonal antibody against AM was succesfully developed. AM was immunohistochemically localized mainly in glomeruli (GEC and endothelial cells), some cortical proximal tubules, medullary collecting duct cells, interstitial cells, vascular smooth muscle cells and endothelial cells. Northern blot assay showed that AM mRNA was expressed only on cultured GEC, but not on MsC, however, AM receptor CRLR mRNA was only expressed on MsC. GEC conditioned medium containing AM can inhibit MsC growth and AM receptor blocker CGRP8-37 may partially decreased this inhibitory effect.

CONCLUSIONAM produced by GEC inhibits the proliferation of MsC, which suggests that AM as an important regulator is involved in glomerular normal physiological functions and pathologic processes.

Adrenomedullin ; Animals ; Antibodies, Monoclonal ; analysis ; Calcitonin Receptor-Like Protein ; Cell Division ; Cells, Cultured ; Epithelial Cells ; cytology ; metabolism ; Female ; Glomerular Mesangium ; cytology ; metabolism ; Kidney Glomerulus ; cytology ; Mice ; Mice, Inbred BALB C ; Peptides ; immunology ; metabolism ; physiology ; RNA, Messenger ; biosynthesis ; Receptors, Calcitonin ; biosynthesis ; genetics