Adrenomedullin is upregulated in the heart and aorta during the early and late stages of sepsis

Although circulating levels of adrenomedullin (ADM), a newly reported vasodilatory peptide with 52 amino acid residues in the human and 50 amino acid residues in the rat, are elevated during the early and late stages of sepsis, ADM levels in cardiovascular tissues and its precise localization remain to be determined. To study this, rats were subjected to sepsis by cecal ligation and puncture (CLP), followed by administration of 3 ml/100 g b.wt. normal saline to these and sham-operated animals. The heart and thoracic aorta were harvested at 5 h (i.e. the early stage of sepsis) and 20 h (late sepsis) after CLP. Tissue levels of ADM were determined by radioimmunoassay. The localization of ADM in the left ventricle and thoracic aorta was examined by using immunohistochemistry and electron microscopy techniques. The results indicated that ADM levels in the heart and thoracic aorta increased significantly at 5 h after CLP and remained elevated at 20 h after the onset of sepsis. Immunohistochemistry findings showed that ADM immunoreaction products were localized in the cytoplasm of the cardiac myocytes and aortic endothelial cells. Using electron microscopy, ADM immunoreaction products were found in the cytoplasmic matrixes. The immunostainings were also associated with the outer membranes of mitochondria and vesicles of the myocytes as well as vascular endothelial cells. It appears that the cardiovascular tissues, among other organ systems, contribute to the increased levels of plasma ADM under those conditions. Since ADM is localized in different cell populations in the heart and the large blood vessel (i.e. myocytes versus vascular endothelial cells), this peptide may play a differential role in regulating cardiac and vascular functions during sepsis as an autocrine and/or paracrine mediator.     

The role of adrenomedullin and its receptor system in cardiovascular calcification of rat induced by Vitamin D(3) plus nicotine

Adrenomedullin (ADM) is a potent vasodilatory peptide which regulates blood pressure, cell growth and bone formation. Our work was aimed to explore the production of ADM, changes and pathophysiological significance of ADM mRNA and ADM receptor components--calcitonin receptor like receptor (CRLR) and receptor activity modifying proteins (RAMPs) mRNA in calcified myocardium and aorta of rats induced by Vitamin D3 plus nicotine. Contents of ADM in plasma, myocardium and aorta were measured by radioimmunoassay (RIA). The amount of ADM, CRLR and RAMPs mRNA was determined by semi-quantitative RT-PCR. The calcium content and alkaline phosphatase activity in myocardium and aorta of rats were measured. The results showed that the contents of calcium in calcified myocardium and aorta were increased by 3.5- and 6-fold (all P < 0.01), respectively, and alkaline phosphatases activity in calcified myocardium and aorta were increased by 66.5 and 82.7% (all P < 0.01 ), respectively, compared with 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 amount of ADM, CRLR and RAMP2 mRNA in calcified myocardium was elevated by 90.6, 157.5 and 119.6% (all P < 0.01), RAMP3 mRNA was decreased by 14.1% (P < 0.01), respectively, compared with control. The amount of ADM, CRLR, RAMP2 and RAMP3 mRNA in calcified aorta was 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 control. The elevated level of CRLR and RAMP2 mRNA were in positive correlation with that of ADM mRNA (r = 0.992 and 0.882, respectively, P < 0.01) in calcified myocardium. The elevated level of CRLR and RAMP3 mRNA were also in positive correlation with that of ADM mRNA (r = 0.727, P < 0.05 and 0.816, P < 0.01, respectively) in calcified aorta. These results demonstrated that calcified myocardium and aorta generated an increased amount of ADM, up-regulated gene expressions of ADM, CRLR and RAMP2 mRNA. While the alteration of RAMP3 mRNA in calcified myocardium and aorta was different. These suggested that ADM and its receptor system might involve in the regulation of calcification in heart and aorta.     

Changes of adrenomedullin and receptor activity modifying protein 2 (RAMP2) in myocardium and aorta in rats with isoproterenol-induced myocardial ischemia

Adrenomedullin is a potent vasodilator peptide originally isolated from a pheochromocytoma. Recently, a novel adrenomedullin receptor has been identified as a complex of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 2 (RAMP2). To explore the pathophysiological roles of adrenomedullin and its receptor component RAMP2 in ischemic cardiovascular diseases, we studied the changes of adrenomedullin and RAMP2 mRNA in myocardium and aorta in rats with isoproterenol (ISO)-induced myocardial impairment. In ISO-treated rats, heart became enlarged markedly, the ratio of heart to body weight was increased by 54% (P<0.01), and myocardial malondialdehyde content and plasma lactate dehydrogenase activity was elevated by 43% (P<0.01) and 138% (P<0.01), respectively. Immunoreactive adrenomedullin (ADM) in plasma, myocardium and aorta was augmented by 116.7% (P<0.01), 50.8% (P<0.01) and 12.5% (P>0.05), respectively. ADM mRNA in myocardium and aorta was increased by 96.8% (P<0.01) and 38.5% (P<0.01), respectively. RAMP2 mRNA in myocardium and aorta was increased by 19.6% (P<0.05) and 15.8% (P<0.01), respectively. These results suggest that the increase of ADM level and the up-regulation of ADM and RAMP2 gene in myocardium and aorta may be significant in the pathogenesis of ischemic myocardiopathy.     

Intermedin/adrenomedullin 2及其受体在慢性低氧性肺动脉高压大鼠右心室的表达变化

本研究探讨了新发现的小分子生物活性肽intermedin／adrenomedullin 2（IMD／ADM2）及其受体在慢性低氧性肺动脉高压大鼠右心室中的变化和可能作用。用放射免疫分析法测定正常对照组和常压低氧4周组Sprague-Dawley大鼠血浆、右心室匀浆IMD／ADM2和肾上腺髓质素（adrenomednllin,ADM）蛋白水平;逆转录-多聚酶链反应法测定右心室IMD／ADM2、ADM及受体：降钙素受体样受体（calcitonin receptor-like receptor,CRLR）、受体活性修饰蛋白1,2,3（receptor activity modifying protein 1,2,3,RAMP1,RAMP2,RAMP3）mRNA表达。结果显示：低氧组平均肺动脉压、右心室与左心室加室间隔重量比[RV／（LV＋S）]显著高于对照组（均P〈0．01）;低氧组血浆和右心室组织匀浆ADM水平比对照组分别高1．26倍和1．68倍（P〈0．01）,IMD／ADM2水平则较对照组分别高0．90倍和1．19倍（P〈0．01）;与对照组相比,低氧组右心室IMD／ADM2、ADM mRNA表达均上调（P〈0．01）,RAMP2 mRNA表达增强（P〈0．05）,而两组间CRLR、RAMP1、RAMP3 mRNA的表达水平无显著性差异。结果表明,慢性低氧性肺动脉高压大鼠IMD／ADM2表达水平升高。     

Pulmonary clearance of adrenomedullin is reduced during the late stage of sepsis

Polymicrobial sepsis is characterized by an early, hyperdynamic phase followed by a late, hypodynamic phase. Although upregulation of adrenomedullin (ADM), a novel potent vasodilatory peptide, plays an important role in producing cardiovascular responses during the progression of sepsis, it remains unknown whether the clearance of this peptide is altered under such conditions. To determine this, male adult rats were subjected to sepsis by cecal ligation and puncture (CLP) followed by fluid resuscitation. At 5 h (i.e., the hyperdynamic phase of sepsis) or 20 h (the hypodynamic phase) after CLP, the animals were injected with 125I-labeled ADM through the jugular vein. Blood and tissue samples (including the lungs, kidneys, gastrointestinal tract, pancreas, spleen, mesentery, liver, brain, skeletal muscle, heart, and skin) were harvested 30 min after the injection and the radioactivity was determined. The results indicate that there were no significant alterations in tissue [125I]ADM distribution at 5 h after CLP compared to shams. At 20 h after CLP, however, there was a significant decrease in radioactivity in the lungs. In contrast, a significant increase of radioactivity was observed in all other organs except the liver and kidneys. The pulmonary distribution of [125I]ADM was found to be far greater than in any other organs tested, irrespective of the effect of sepsis. In separate groups of animals, injection of [125I]ADM into the left ventricle resulted in a significant decrease in radioactivity in the lungs of both sham and septic animals at 20 h after surgery. These results suggest that the lungs are the primary site of ADM clearance, which is significantly diminished during the late stage of sepsis. The decreased clearance of ADM by the lungs may play an important role in maintaining the sustained levels of plasma ADM under such conditions.     

自发性高血压大鼠和Wistar-Kyoto大鼠心血管组织肾上腺髓质素和肾上腺髓质素原N-末端20肽的水平

本工作观察了自发性高血压大鼠 (SHRs)和Wistar kyoto (WKY)大鼠心肌和主动脉肾上腺髓质素 (a drenomedullin ,ADM)和肾上腺髓质素原N 末端 2 0肽 (proadrenomedullinNterminal 2 0peptide ,PAMP)的水平。以放射免疫分析方法测定血浆、心肌和主动脉ADM含量。用竞争性定量逆转录多聚酶链式反应 (RT PCR)方法测定心肌和主动脉ProADMmRNA含量。结果发现 ,SHRs心肌和主动脉ProADMmRNA水平分别比WKY大鼠高 66 7%和 73 % (均P <0 0 1)。SHRs血浆、心肌和主动脉ADM ir含量分别较WKY大鼠高 2 9%、76 7%和 79% (均P <0 0 1)。SHRs血浆、心肌和主动脉PAMP ir水平分别较WKY大鼠高 42 5 % (P <0 0 1)、47 2 % (P <0 0 1)和 2 7 3 % (P <0 0 5 )。另外 ,SHRs的ADM和PAMP的比值较WKY大鼠明显增高 (心肌和主动脉分别为 2 0± 0 2 5vs 1 64± 0 3和 2 2± 0 18vs 1 5 6± 0 2 8)。结果提示 ,SHRs心肌和主动脉ProADM基因表达上调 ,ADM和PAMP水平升高 ,但二者升高的比例不一致。SHRs的ADM和PAMP升高不一致的病理生理意义有待进一步研究     

Expression of endothelin-1 system in a pig model of endotoxic shock

Endothelin (ET)-1 is a potent vasoconstrictive peptide and it is involved in the pathogenesis of septic shock. Blockade of ET-1 receptors abolishes the LPS-induced pulmonary hypertension and worsens the LPS-dependent systemic hypotension, but the role of ET-1 in sepsis remains uncertain. To determine the role of ET-1 in cardiovascular and respiratory derangement in a porcine model of endotoxemic shock we evaluated ET-1 plasma levels and ET-1 mRNA and protein levels in lung, liver, and heart as well as Endothelin Converting Enzyme-1, ET(A) and ET(B) receptors mRNA in the same tissues. Twelve piglets were randomised to sham operated or to LPS-treated (40 microg/kg/h for 4 h) groups. During the experiment, respiratory and circulatory parameters have been recorded and blood samples collected. At the end of the experiment the animals were sacrificed and tissue samples collected for real-time quantitative PCR and ELISA test. LPS infusion evokes a large increase in ET-1 plasma concentration, and in tissues mRNA levels, associated with an increase in pulmonary arterial pressure, as well as in pulmonary and systemic vascular resistances, and a decrease in stroke volume. LPS infusion caused also a derangement of respiratory mechanics, evidenced by an increase in resistance and a decrease in compliance of the respiratory system. ET(A) and ET(B) receptor mRNA levels were markedly decreased in liver and lung and slightly increased in heart, evidencing that ET receptor subtypes were differentially regulated in the major organs of endotoxin treated pigs. In conclusion our data show the presence of a continuative and differentially regulated stimulating mechanism of ET-1 expression during pig endotoxaemia as well as a fundamental role of ET-1 system in the cardiovascular and respiratory derangement.     

Regulation of cardiac adrenomedullin in heart failure.

Adrenomedullin (ADM), a potent natriuretic and vasorelaxing peptide with inotropic properties, is elevated in plasma in human and experimental congestive heart failure (CHF). Recent studies suggest that angiotensin II stimulates ADM production and secretion from cardiac myocytes and fibroblasts. In the present study, we investigated cardiac ADM in experimental CHF, and tested the hypothesis that angiotensin converting enzyme (ACE) inhibition modulates cardiac ADM in CHF. Cardiac tissue ADM immunoreactivity and gene expression were assessed by radioimmunoassay, immunohistochemistry, in situ hybridization and Northern blot analysis in normal and CHF dogs in the presence and absence of ACE inhibition. Experimental CHF was produced by progressive rapid ventricular pacing and characterized by increased ventricular ADM concentrations as well as increased ventricular ADM gene expression. ACE inhibition abolished the increases in ventricular ADM concentrations and ventricular ADM gene expression in CHF. Ventricular ADM gene expression was localized to ventricular myocytes and correlated with left ventricular mass index, suggesting that ventricular ADM is a marker for ventricular hypertrophy. In contrast, atrial ADM concentrations and gene expression did not change in CHF with or without ACE inhibition. Increased plasma ADM concentrations in CHF were also abolished with ACE inhibition. The present study demonstrates that circulating and ventricular ADM are activated in pacing-induced experimental CHF and that ACE inhibition reverses ventricular ADM activation in CHF. This study also indicates that cardiac ADM gene expression is differently regulated between atrium and ventricle in CHF.     

左旋硝基精氨酸诱导的高血压大鼠心肌和血管的肾上腺髓质素与受体活性修饰蛋白2表达的变化

探讨高血压大鼠心肌和血管的肾上腺髓质素（adrenomedullin,ADM）与受体活性修饰蛋白2（receptoractivity-modifying protein 2,RAMP2）mRNA的变化。用一氧化氮合酶（NOS）竞争性抑制剂左旋硝基精氨酸（L-NNA）阻断NOS制备大鼠高血压模型。用放射免疫分析方法测定血浆、心肌和血管ADM含量,及竞争性定量RT-PCR方法测定心肌和血管ADM mRNA与RAMP2 mRNA含量。结果表明,NOS阻断剂L-NNA应用4周后动物血压明显升高、心肌肥厚。心重（mg）/体重（g）比值增加35.5％（P<0.01）。血浆、心肌和血管的ADM-ir较对照组分别增加80％、72％和57％（均P<0.01）。高血压大鼠心肌和血管ADM mRNA含量显著增加,分别较正常大鼠高50％（P<0.05）和102.9％（P<0.05）。高血压大鼠心肌和血管的RAMP2　mRNA含量均显著增加,分别较正常大鼠高132％（P<0.01）和87％（P<0.01）。高血压大鼠心肌和血管ADM的升高与RAMP2的升高程度呈明显的正相关,其相关系数分别为0.741和0.885。上述观察结果表明,高血压时血浆、心肌和血管ADM水平升高,心肌和血管ADM与RAMP2基因表达上调,提示ADM/RAMP2系统在高血压发病中可能具有重要作用。     

Adrenomedullin gene expression and peptide levels in the heart and blood vessels of streptozotocin-diabetic rats.

The aim of the present study was to assess the changes in gene expression and peptide adrenomedullin (AM) levels in cardiovascular and other tissues in the streptozotocin-diabetic rats. For this purpose, diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg body weight). Half of the diabetic rats were subcutaneously injected with insulin in the afternoon (4 units/day) one week after STZ injection until the day before killing. Control rats received only saline injection. AM mRNA was determined in cardiovascular and other tissues of streptozotocin-diabetic rats using solution-hybridization-RNase protection assay. Circulating AM and peptide AM in cardiovascular and other tissues were estimated using a specific radioimmunoassay. There were increases in preproAM mRNA levels in the left and right ventricles and in the thoracic aorta in both the 2-week and 4-week diabetic rats, but not in the two atria, the mesenteric artery and the lung. In the 2-week diabetic rats, there were decreases in AM contents in the two atria and the lung but an increase in the thoracic aorta. In the 4-week diabetic rats, there were bigger decreases in the atria and also a decrease in the left ventricle. The plasma AM levels were not changed but there was an increase in the excretion of AM in the urine. Our results suggest a possible increase in AM release in the heart and the thoracic aorta in the 2-week and 4-week diabetic rats.     

Down regulation of kidney neutral endopeptidase mRNA,protein and activity during acute renal failure: Possible mechanism for ischemia-induced acute renal failure in rats?

Neutral endopeptidase (NEP, 24.11) is an ectoenzyme involved in the degradation of peptide hormones such as endothelin (ET), atrial natriuretic factor and enkephalins. The current study was designed to assess the involvement of NEP in ischemia-induced acute renal failure (ARF). In unilaterally nephrectomized Sprague-Dawley rats, the left renal artery was occluded for 30 min under pentobarbital anesthesia (40 mg/kg, i.p.) at 37°C. In addition to plasma creatinine levels, NEP activity was determined in renal cortical membranes at 0, 2, 5, and 24 h following reperfusion. Plasma creatinine levels significantly increased at 2, 5 and 24 h. There was a significant decrease in NEP activity as early as 2 h following reperfusion that was maintained up to 24 h (57.9 ± 4%) with a concomitant loss of enzyme protein shown by Western analysis. Northern analysis of kidney cortical RNA, probed with an NEP cDNA, showed a 45% decrease in NEP mRNA level by the end of the ischemic period and decreased further during reperfusion. Thus, decrease in NEP mRNA levels preceded the changes in protein level, enzyme activity and plasma creatinine levels. These data, along with the reported increase in the tissue level of ET in kidney cortex, and the beneficial effect of ET antibody as well as ET receptor antagonist in ARF, suggest that down regulation of NEP, one of the mechanisms leading to increased tissue level of ET, may be a contributing factor to ARF.     

Hypertension induced by nitric oxide synthase inhibitor increases responsiveness of ventricular myocardium and aorta of rat tissue to adrenomedullin stimulation in vitro

In this work, we aimed to observe the changes in adrenomedullin (ADM) and its receptor-calcitonin receptor-like receptor (CL), receptor activity-modifying protein (RAMP) 1, RAMP2 and RAMP3-in cardiac ventricles and aortas of hypertensive rats, and the responsiveness of injured cardiovascular tissue to ADM, then to illustrate the protective mechanism of ADM on the cardiovascular system. Male SD rats were subjected to treatment with chronic N(G)-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase. The ADM contents and cAMP production in myocardia and aortas were measured by RIA. The mRNA levels of ADM, CL, and RAMP1-3 were determined by RT-PCR. L-NNA induced severe hypertension and cardiomegaly. The ir-ADM content in plasma, ventricles and aortas in L-NNA-treated animals increased by 80%, 72% and 57% (all p<0.01), respectively. Furthermore, mRNA levels of ADM, CL, RAMP2 and RAMP3 were elevated by 91%, 33%, 50% and 72.5% (all p<0.01), respectively, in ventricles and by 95%, 177%, 74.7% and 85% (all p<0.01), respectively, in aortas. mRNA level of RAMP1 was elevated by 129% (p<0.01) in aortas but no significant difference in ventricles. The elevated mRNA levels of RAMP2 and RAMP3 were positively correlated with that of ADM in hypertrophic ventricles (r=0.633 and 0.828, p<0.01, respectively) and the elevated mRNA levels of CL, RAMP2 and RAMP3 were positively correlated with that of ADM in aortas (r=0.941, 0.943 and 0.736, all p<0.01, respectively). The response of ventricular myocardia and aortas to ADM administration potentiated, and the production of cAMP was increased by 41% and 68% (both p<0.01), respectively. ADM-stimulated cAMP generation in ventricular myocardia and aortas was blocked by administration of both ADM22-52, the specific antagonist of ADM receptor, and CGRP8-37, the antagonist of the CGRP1 receptor. The results showed an increased in cardiovascular ADM generation and an up-regulation of the gene expression of ADM and its receptor-CL, RAMP1-3 during hypertension, augmented responsiveness of ventricular myocardia and aortas of hypertensive rats to ADM, suggesting that these receptors may play a role in the cardiovascular adaptation in response to sub-chronic NO-inhibition.     

Chronic administration of adrenomedullin attenuates hypoxic pulmonary vascular structural remodeling and inhibits proadrenomedullin N-terminal 20-peptide production in rats

Adrenomedullin (ADM) is a novel cardiovascular-active peptide involved in vasodilation, reducing blood pressure and inhibiting vascular smooth muscle cell migration and proliferation. Previous research showed that ADM might be involved in the development of pulmonary hypertension. In this study, we investigated the effect of ADM subcutaneously administered by mini-osmotic pump (300 ng/h) on pulmonary hemodynamics and pulmonary vascular structure in hypoxic rats, as well as the influence of ADM on the proadrenomedullin N-terminal 20-peptide (PAMP) protein and mRNA expressions and its plasma concentrations. The results showed that ADM obviously decreased mean pulmonary artery pressure and the ratio of right ventricular mass to left ventricular plus septal mass in hypoxic rats. Chronic infusion of ADM lessened the muscularization of small pulmonary vessels, attenuated relative medial thickness and relative medial area of pulmonary arteries, and alleviated the ultrastructural changes in pulmonary arteries of hypoxic rats. ADM inhibited the proliferation of pulmonary artery smooth muscle cells, represented by a decrease in the expression of proliferative cell nuclear antigen (PCNA) in the pulmonary artery. Meanwhile, plasma PAMP concentration and the expression of PAMP protein and mRNA by pulmonary arteries in rats of hypoxia with ADM group were markedly decreased compared with those in hypoxic group. The results suggest that ADM ameliorated the development of hypoxic pulmonary vascular structural remodeling. Intramolecular regulation of ADM may play an important role in the regulation of hypoxic pulmonary hypertension by ADM.     

Resection upregulates the IGF-I system of parenterally fed rats with jejunocolic anastomosis

Rats maintained with parenteral nutrition following 60% jejunoileal resection plus cecectomy exhibit minimal adaptive growth in the residual jejunum but a dramatic adaptive growth in the residual colon. Coinfusion of insulin-like growth factor I (IGF-I) with parenteral nutrition induces jejunal growth but has minimal effects in the colon. Our objective was to study the role of the endogenous IGF-I system in the differential responses of jejunum and colon to resection and/or IGF-I during parenteral nutrition. We measured concentrations of immunoreactive IGF-I in plasma, jejunum, and colon, IGF-I receptor binding, and levels of IGF receptor, IGF-I, IGF binding protein (IGFBP)-3 and IGFBP-5 mRNA in residual jejunum and colon 7 days after resection and/or IGF-I treatment. IGF-I receptor number was increased (74-99%) in jejunum and colon due to resection; IGF-I mRNA was increased 5-fold in jejunum and 15-fold in colon due to resection. Resection increased circulating IGFBPs but did not alter plasma IGF-I concentration. Resection induced colonic growth in association with significantly greater colonic IGFBP-5 mRNA and significantly lower colonic immunoreactive IGF-I. IGF-I treatment had no significant effect on IGF-I mRNA or IGF-I receptor number. Concentrations of plasma and jejunal immunoreactive IGF-I were significantly increased in rats given IGF-I in association with jejunal growth. IGF-I treatment significantly increased IGFBP-5 mRNA in the jejunum, which also correlated with jejunal growth. Thus resection upregulated IGF-I receptor number and IGF-I mRNA in residual jejunum and colon, but differential adaptation of these segments correlated with differential regulation of IGFBP-5 mRNA.     

Identification of circRNA and mRNA expression profiles and functional networks of vascular tissue in lipopolysaccharide‐induced sepsis

Sepsis is the most common cause of death in intensive care units. This study investigated the circular RNA (circRNA) and mRNA expression profiles and functional networks of the aortic tissue in sepsis. We established a lipopolysaccharide (LPS)‐induced rat sepsis model. High‐throughput sequencing was performed on the aorta tissue to identify differentially expressed (DE) circRNAs and mRNAs, which were validated by real‐time quantitative polymerase chain reaction (RT‐qPCR). Bioinformatic analysis was carried out and coding and non‐coding co‐expression (CNC) and competing endogenous RNA (ceRNA) regulatory networks were constructed to investigate the mechanisms. In total, 373 up‐regulated and 428 down‐regulated circRNAs and 2063 up‐regulated and 2903 down‐regulated mRNAs were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of mRNAs showed that the down‐regulated genes were mainly enriched in the process of energy generation. CNC and ceRNA regulatory networks were constructed with seven DE circRNAs. The results of functional enrichment analysis of CNC target genes revealed the important role of circRNAs in inflammatory response. The ceRNA network also highlighted the significant enrichment in calcium signalling pathway. Significant alterations in circRNAs and mRNAs were observed in the aortic tissue of septic rats. In addition, CNC and ceRNA networks were established.     

Exercise training promotes expression of apelin and APJ of cardiovascular tissues in spontaneously hypertensive rats

Because apelin may play an important regulatory role in human cardiac dysfunction, we investigated alterations in cardiovascular content of apelin and its receptor, APJ, during hypertension and the effect of exercise training on the cardiovascular apelin/APJ system in hypertensive animals. Spontaneously hypertensive rats (SHRs) underwent swimming training consisting of 54 swimming sessions of 60 min each (6 days/week for 9 weeks). Systolic blood pressure (SBP) was verified weekly by tail-cuff plethysmography. Apelin levels in plasma and cardiovascular tissues were determined by radioimmunoassay. The level of apelin/APJ mRNA was determined by RT-PCR. SHRs showed severe hypertension and pathological cardiomegaly. The level of apelin immunoreactivity (apelin-ir) in plasma and ventricular and aortic tissues was lower, by 40%, 40% and 42% (all P<0.01), respectively, in SHRs than in control Wistar-Kyoto rats, and the mRNA level of apelin and APJ in myocardium and aorta was markedly decreased. Compared with sedentary SHRs, swimming-trained SHRs showed decreased SBP and elevated mRNA expression of apelin and APJ in cardiovascular tissues and elevated apelin-ir level in plasma, myocardium and aorta (all P<0.01). SBP and level of apelin-ir in plasma and cardiovascular tissues were negatively correlated. Long-term swimming training relieved the pathogenesis of hypertension and reversed the downregulation of the cardiovascular apelin/APJ system induced by hypertension, which suggests that the improving effect of exercise training on hypertension could be mediated by upregulating the cardiovascular apelin/APJ system.     

Adrenomedullin(27-52) inhibits vascular calcification in rats

Adrenomedullin (ADM) has the vasodilatory properties and involves in the pathogenesis of vascular calcification. ADM could be degraded into more than six fragments in the body, including ADM(27-52), and we suppose the degrading fragments from ADM do the same bioactivities as derived peptides from pro-adrenomedullin. The present study carries forward by assessing the effects on vascular calcification of the systemic administration of ADM(27-52). The rat vascular calcific model was replicated with vitamin D3 and nicotine. ADM or/and ADM(27-52) were systemically administrated with mini-osmotic pump beginning at seventh day after the model replication for 25 days. Vascular calcific nodules histomorphometry, vascular calcium content, vascular calcium uptake, alkaline phosphatase activity, and osteopontin-mRNA quantification in aorta were assessed. ADM limited 40.2% vascular calcific nodules (P<0.01), did not effect on calcium content (P>0.05), reduced 44.4% calcium uptake (P<0.01), lowered 21.1% alkaline phosphatase activity (P<0.01), and regulated 40.9% downwards osteopontin-mRNA expression (P<0.01) in the aorta of rats with vascular calcification. ADM(27-52) receded 32.0% vascular calcific nodules (P<0.01), taken from 55.5% calcium content (P<0.01), did not affect calcium uptake (P>0.05), inhibited 22.5% alkaline phosphatase activity (P<0.01), and restrained 21.9% osteopontin-mRNA expression (P<0.01) in the aorta of rats with vascular calcification. Both of ADM and ADM(27-52) did interact on vascular calcification each other. ADM could partially antagonize the effects of ADM(27-52) in taking from calcium content (17.5%, P<0.01) and in receding vascular calcific nodules (18.6%, P<0.01). ADM could obviously enhance the action of ADM(27-52) in inhibiting alkaline phosphatase activity (14.4%, P<0.01) and in reducing calcium uptake (11.4%, P<0.01). ADM(27-52) could partially antagonize the effects of ADM on regulating downwards osteopontin-mRNA expression (17.0%, P<0.01). It is concluded that ADM(27-52) derived from ADM acts as an inhibitory agent on vascular calcification, with special mechanisms different from ADM derived from ADM progenitor molecule.