Specific Overexpression of YAP in Vascular Smooth Muscle Attenuated Abdominal Aortic Aneurysm Formation by Activating Elastic Fiber Assembly via LTBP4.

Abdominal aortic aneurysm (AAA) is a fatal vascular disease. Vascular smooth muscle cells (VSMCs) play a crucial role in the pathogenesis of AAA. Increasing evidence has shown that Yes-associated protein (YAP) is involved in diverse vascular diseases. However, the role of YAP in AAA remains unclear. The current study aimed to determine the role of YAP in AAA formation and the underlying mechanism. We found that YAP expression in VSMCs was markedly decreased in human and experimental AAA samples. Furthermore, VSMC-specific YAP overexpression prevented several pathogenic factor-induced AAA. Mechanistically, YAP overexpression in VSMCs promoted latent transforming growth factor-ß binding protein 4 (LTBP4) expression, an important factor in elastic fiber assembly. Finally, silencing of LTBP4 in VSMCs abolished the protective role of YAP in AAA formation in vivo. Our results suggest that YAP promotes LTBP4-mediated elastic fibril assembly in VSMCs, which mitigates elastin degradation and AAA formation.

Mirabegron Ameliorated Atherosclerosis of ApoE-/- Mice in Chronic Intermittent Hypoxia but Not in Normoxia.

PURPOSE: It has been established that obstructive sleep apnea (OSA) is an independent risk factor for atherosclerosis. Chronic intermittent hypoxia (CIH) activates sympathoadrenal system and upregulates ß3 adrenergic receptor (ß3 AR). However, the effect of selective ß3 AR agonist mirabegron in CIH-induced atherosclerosis remains unknown. METHODS: We generated a CIH-induced atherosclerosis model through exposing ApoE-/- mice to CIH (8 h per day, cyclic inspiratory oxygen fraction 5-21%, 60-s cycle) for 6 weeks after 4-week high-fat dieting and investigated the effects of mirabegron, a selective ß3 AR agonist, on CIH-induced atherosclerosis. The coronary endarterectomy (CE) specimens from coronary artery disease patients with OSA and without OSA were collected. RESULTS: The expression of ß3 AR was significantly elevated in CIH-induced atherosclerosis model. Furthermore, treatment with mirabegron (10mg/kg per day by oral administration for 6 weeks) ameliorated atherosclerosis in ApoE-/- mice in CIH but not in normoxia. Mechanistically, mirabegron activated ß3 AR and ameliorated intraplaque oxidative stress by suppressing p22phox expression and reactive oxygen species (ROS) level. In addition, in human CE specimens, ß3 AR was also upregulated associated with increased p22phox expression and ROS level both in the lumen and in the plaque of coronary artery in OSA subjects. CONCLUSION: This study first demonstrated that mirabegron impeded the progression of CIH-induced atherosclerosis, at least in part, via ß3 AR-mediated oxidative stress, suggesting a promising therapeutic strategy for protecting against atherosclerosis induced by CIH.

Brown Adipose Tissue Activation Is Involved in Atherosclerosis of ApoE-/- Mice Induced by Chronic Intermittent Hypoxia.

Background: Obstructive sleep apnea is an atherogenesis factor of which chronic intermittent hypoxia is a prominent feature. Chronic intermittent hypoxia (CIH) exposure can sufficiently activate the sympathetic system, which acts on the ß3 adrenergic receptors of brown adipose tissue (BAT). However, the activity of BAT and its function in CIH-induced atherosclerosis have not been fully elucidated. Methods: This study involved ApoE-/- mice which were fed with a high-fat diet for 12 weeks and grouped into control and CIH group. During the last 8 weeks, mice in the CIH group were housed in cages to deliver CIH (12 h per day, cyclic inspiratory oxygen fraction 5-20.9%, 180 s cycle). Atherosclerotic plaques were evaluated by Oil Red O, hematoxylin and eosin, Masson staining, and immunohistochemistry. Afterward, we conducted immunohistochemistry, western blotting, and qRT-PCR of uncoupling protein 1 (UCP1) to investigate the activation of BAT. The level of serum total cholesterol (TC), triglyceride, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and free fatty acid (FFA) were measured. Finally, RNA-Sequencing was deployed to explore the differentially expressed genes (DEGs) and their enriched pathways between control and CIH groups. Results: Chronic intermittent hypoxia exposure promoted atherosclerotic plaque area with increasing CD68, α-SMA, and collagen in plaques. BAT activation was presented during CIH exposure with UCP1 up-regulated. Serum TC, triglyceride, LDL-c, and FFA were increased accompanied by BAT activation. HDL-c was decreased. Mechanistically, 43 lipolysis and lipid metabolism-associated mRNA showed different expression profiling between the groups. Calcium, MAPK, and adrenergic signaling pathway included the most gene number among the significantly enriched pathways. Conclusion: This study first demonstrated that BAT activation is involved in the progression of CIH-induced atherosclerosis, possibly by stimulating lipolysis.

The establishment of a homozygous SNTA1 knockout human embryonic stem cell line (WAe009-A-50) using the CRISPR/Cas9 system.

SNTA1 encodes α1-syntrophin, a scaffold protein, which is a component of the dystrophin-associated protein complex. Additionally, α1-syntrophin interacts with SCN5A and nNOS-PMCA4b complex in cardiomyocytes. SNTA1 is a susceptibility locus for arrhythmia and cardiomyopathy. We generated a homozygous SNTA1 knockout human embryonic stem cell (H9SNTA1KO) using the CRISPR/Cas9 system. H9SNTA1KO maintained pluripotency and a normal karyotype and differentiated into three germ layers in vivo.

Ascorbic acid can promote the generation and expansion of neuroepithelial-like stem cells derived from hiPS/ES cells under chemically defined conditions through promoting collagen synthesis.

INTRODUCTION: Spinal cord injury (SCI) is a neurological, medically incurable disorder. Human pluripotent stem cells (hPSCs) have the potential to generate neural stem/progenitor cells (NS/PCs), which hold promise in the treatment of SCI by transplantation. In our study, we aimed to establish a chemically defined culture system using serum-free medium and ascorbic acid (AA) to generate and expand long-term self-renewing neuroepithelial-like stem cells (lt-NES cells) differentiated from hPSCs effectively and stably. METHODS: We induced human embryonic stem cells (hESCs)/induced PSCs (iPSCs) to neurospheres using a newly established in vitro induction system. Moreover, lt-NES cells were derived from hESC/iPSC-neurospheres using two induction systems, i.e., conventional N2 medium with gelatin-coated plates (coated) and N2+AA medium without pre-coated plates (AA), and were characterized by reverse transcription polymerase chain reaction (RT-PCR) analysis and immunocytochemistry staining. Subsequently, lt-NES cells were induced to neurons. A microelectrode array (MEA) recording system was used to evaluate the functionality of the neurons differentiated from lt-NES cells. Finally, the mechanism underlying the induction of lt-NES cells by AA was explored through RNA-seq and the use of inhibitors. RESULTS: HESCs/iPSCs were efficiently induced to neurospheres using a newly established induction system in vitro. lt-NES cells derived from hESC/iPSC-neurospheres using the two induction systems (coated vs. AA) both expressed the neural pluripotency-associated genes PAX6, NESTIN, SOX1, and SOX2. After long-term cultivation, we found that they both exhibited long-term expansion for more than a dozen generations while maintaining neuropluripotency. Moreover, the lt-NES cells retained the ability to differentiate into general functional neurons that express ß-tubulin at high levels. We also demonstrated that AA promotes the generation and long-term expansion of lt-NES cells by promoting collagen synthesis via the MEK-ERK1/2 pathway. CONCLUSIONS: This new chemically defined culture system was stable and effective regarding the generation and culture of lt-NES cells induced from hESCs/iPSCs using serum-free medium combined with AA. The lt-NES cells induced under this culture system maintained their long-term expansion and neural pluripotency, with the potential to differentiate into functional neurons.

Lipidomics reveals the dynamics of lipid profile altered by omega-3 polyunsaturated fatty acid supplementation in healthy people.

Glycerophospholipids (GPs) and sphingolipids (SPs) are important lipid components in the body and play biological functions. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are important nutrients, and their supplements are commonly used for preventing some diseases. However, the effect of n-3 PUFAs on the human glycerophospholipidome and sphingolipidome is unclear. We used targeted lipidomics to study the GP and SP profile of healthy individuals after supplementation with n-3 PUFAs for 3, 7, 14 and 21 days. Fuzzy c-means clustering was used to cluster the lipid species into six classes reflecting different changed-content patterns after n-3 PUFA supplementation. Among the species with significantly changed content, lysophospholipids were the most sensitive; their content started to increase on day 3. The content of phosphatidylserines increased at a later stage. The content of most of the phosphatidylcholines and alkylphosphatidylcholines decreased on day 21. A correlation network analysis of lipid species suggested that some enzymes involved in the metabolism of lysophospholipids and phosphatidylserines were regulated by n-3 PUFAs. Levels of creatine kinase-MB (CK-MB), urea, glucose, triglycerides and total bilirubin were altered by n-3 PUFA at 21 days. Correlation analysis revealed that the level of CK-MB was negatively correlated with those of species in lysophosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine and phosphatidylserine classes, which were increased by n-3 PUFA supplementation. With the analysis in this work, we demonstrated the regular pattern of n-3 PUFAs on GP and SP metabolism, which provides a pharmacological basis for n-3 PUFAs for clinical application.

Thoracic Endoscopic-Assisted Mini-Open Surgery for Thoracic and Thoracolumbar Spinal Cord Compression.

Intervertebral disc herniation is a common cause of spinal cord compression, especially for the thoracic and thoracolumbar spinal cord, which has limited buffer space in the spinal canal. Spinal cord compression usually causes decreased sensation and paralysis of limbs below the level of compression, urinary and fecal incontinence, and/or urinary retention, which brings great suffering to the patients and usually requires surgical intervention. Thoracotomy or abdominothoracic surgery is usually performed for the thoracolumbar cord compression caused by hard intervertebral disc herniation. However, there is high risk of trauma and complications with this surgery. To reduce the surgical trauma and obtain good visibility, we designed athoracic endoscopic-assisted mini-open surgery for thoracic and thoracolumbar disc herniation, and performed this procedure on 10 patients who suffered from hard thoracic or thoracolumbar spinal cord compression. During the procedure, the thoracic endoscopy provided clear vision of the surgical field with a good light source. The compression could be fully exposed and completely removed, and no nerve root injury or spinal cord damage occurred. All patients achieved obvious recovery of neurological function after this procedure. This technique possesses the merits of minimal trauma, increased safety, and good clinical results. The aim of this study is to introduce this thoracic endoscopic-assisted mini-open surgery technique, and we believe that this technique will be a good choice for the thoracic and thoracolumbar cord compression caused by hard intervertebral disc herniation.

Plasma level of mitochondrial coupling factor 6 increases in patients with type 2 diabetes mellitus.

Coupling factor 6 (CF6) is a novel endogenous inhibitor of prostacyclin. Plasma CF6 and 6-keto-PGF(1a) were measured by radioimmunoassay in 70 consecutively recruited patients with type 2 diabetes and in 56 healthy controls. A significantly increased plasma CF6 level was found in diabetics compared with controls. The CF6 level was inversely correlated with plasma 6-keto-PGF(1a) level and positively correlated with blood glucose and lipids. These results suggest that CF6 might be an obvious marker of impaired endothelium and might contribute to vascular damage in diabetes.

[Lysophosphatidic acid activates L-arginine/nitric oxide pathway of platelets in rats].

OBJECTIVE: To investigate the mechanism of platelet function caused by Lysophosphatidic acid (LPA), by observing the change of the L-arginine/nitric oxide synthase/nitric oxide (L-Arg/NOS/NO) pathway of platelet in rats. METHODS: LPA (10(-6), 10(-5) and 5x10(-5) mol/L) was administrated in rats and incubated for 30 and 60 minutes. The nitrite production was measured by Greiss assay; NOS activities and L-arginine transportation were detected by isotope tracer method and intracellular [Ca(2+)]i changes by fluorescent probe. RESULTS: LPA increased NO release by 35% and 56%, after incubating for 30 and 60 minutes, respectively. LPA (10(-6), 10(-5)aand 5x10(-5) mol/L) enhanced the NO productions of platelets in a concentration-dependent manner (P<0.01). EC(50) was 17.8 micromol/L, and 95% CI was 13.3-24.2 micromol/L, involved in the physiological concentration of LPA in plasma (P<0.01). Simultaneously, different doses of LPA increased NOS activities and L-arginine uptake in a dose-dependent manner (P<0.01). In this study, LPA (50 micromol/L) increased the intracellular free calcium ion concentration ([Ca(2+)]i, P<0.01), after incubating for 30 and 60 minutes. Pre-treated with NOS inhibitor-L-NAME for 20 minutes, LPA obviously enhanced the effects by 20% and 32% respectively (P<0.01). On the contrary, pre-treated with L-arginine (200 micromol/L) for the same times obviously reduced the effects by 14% and 18% respectively (P<0.01). CONCLUSION: LPA increased NO release by enhancing L-arginine uptake and NOS activities, up-regulating L-arginine/NOS/NO pathway in platelets of rats.

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.

Changes in production and metabolism of brain natriuretic peptide in rats with myocardial necrosis.

In this study, we employed rat model of acute myocardial necrosis induced by isoproterenol (ISO) to study the possible roles of corin, the protease uniquely distributing in myocardium to convert pro-brain natriuretic peptide (proBNP) to BNP, and neutral endopeptidase (NEP), the major enzyme to degrade BNP, in changing the levels of BNP. In rats with isoproterenol alone, the myocardium necrosis occurred and the cardiac function was inhibited; the BNP contents in plasma and myocardium were upregulated, so did the myocardial corin mRNA level; the NEP activity in plasma and myocardium were downregulated. Omapatrilat (OMA) treatment relieved myocardial lesions and improved cardiac function. In the plasma and myocardium, omapatrilat treatment increased BNP contents, reduced NEP activity; in myocardium, mRNA level of proBNP and corin decreased, but NEP mRNA expression increased. Our study confirmed that omapatrilat treated myocardial necrosis effectively and suggested that increased BNP in rats with myocardial necrosis could depend on increased production and conversion as well as decreased degradation.

Relationship between the contents of adrenomedullin and distributions of neutral endopeptidase in blood and tissues of spontaneously hypertensive rats.

Adrenomedullin (ADM) is a multifunctional peptide with important roles in the cardiovascular system, especially in the adjustment of cardiovascular and renal homeostasis. ADM is present in plasma, organs and tissues, and its activity increases during hypertension. It remains unknown whether the clearance of this peptide is altered during hypertension. Neutral endopeptidase (NEP) is the major enzyme in ADM's degradation. We observed the activity and distribution of NEP and the expression of its mRNA in the plasma, cardiac ventricle, aorta, jejunum and kidney of spontaneously hypertensive rats (SHRs) in order to study the possible role of NEP in elevating tissue ADM concentrations during hypertension. ADM and NEP were diffuse in all tissues studied. The level of tissue ADM was generally higher in SHR tissues than in control tissues, except in the renal medulla, and its mRNA expression was higher in all tissues. Plasma NEP activity, general NEP activity and the expression of NEP mRNA in the left ventricle, aorta and jejunum in SHRs was lower than that of controls, and the level of ADM was inversely correlated with NEP activity. NEP activity and mRNA and protein expression in SHR kidneys were higher than in control kidneys; moreover, the ADM content was positively correlated with NEP activity in the renal cortex. NEP activity in the lung of SHRs did not differ from that of controls. Thus, in SHRs, the local concentration and action of ADM in the tissues may be differentially regulated by NEP.

Relationship between contents of adrenomedullin and distributions of neutral endopeptidase in blood and tissues of rats in septic shock.

Adrenomedullin (ADM), a multifunction peptide with important roles in regulating cardiovascular homeostasis, has the vasodilatory properties and is of particular interest in the pathophysiology of sepsis. ADM levels in plasma and tissues are regulated by the proteolysis of neutral endopeptidase (NEP), the major enzyme of ADM degradation. We observed the NEP activity in the plasma, the activity and distribution of NEP and its mRNA expression in the tissues of rats in septic shock to study the possible role of NEP in elevating tissue ADM concentration during sepsis. ADM level increases progressively during sepsis except in the jejunum. Rats in early phase of shock (ES) showed diverse changes in tissue NEP activity. Plasma NEP activity, tissue NEP activity and its protein and mRNA expression in the left ventricle, aorta, jejunum and lung in the late phase of shock (LS) rats were lower than those in ES and the control, but no statistical change of NEP activity in the kidney was observed. The level of ADM was inversely correlated with NEP activity in the plasma, ventricle and aorta and positively correlated with NEP activity in the jejunum. Thus, in sepsis, the local concentration and action of ADM in tissues may be differentially regulated by NEP.

[Hydrogen sulfide: a novel cardiovascular functional regulatory gas factor].

Hydrogen sulfide (H(2)S) may be endogenously produced by cystathionine beta-lyase (CBS) and cystathionine gamma-lyase (CSE) as a cardiovascular physiological functional factor. On the hypoxic pulmonary hypertension (HPH) animal model, the plasma H(2)S concentration, the gene expression and the activity (CSE) were decreased in lung tissues In L-NAME induced hypertension and spontaneous hypertension rats (SHR) models, the plasma H(2)S concentration, vascular CSE activity and mRNA expression were obviously decreased. When H(2)S was exogenously supplied, systolic pressure obviously decrease. These studies suggested that CSE/H(2)S pathway participated in the pathophysiological development of hypertension. The endogenous level of H(2)S produced by some arterial tissues increased in both septic and endotoxic shock rats. The level of H(2)S highly correlated with the endogenous level of NO. These results suggest that H(2)S may be a novel cardiovascular functional regulator.

Plasma mitochondrial coupling factor 6 in patients with acute myocardial infarction.

Previous studies have shown that mitochondrial coupling factor 6 (CF6) is an endogenous peptide that inhibits prostacyclin (PGI2) synthesis in vascular endothelial cells. In this study, we measured the plasma CF6 level of patients with acute myocardial infarction (AMI) to observe dynamic changes of CF6. All patients showed elevated plasma CF6 levels upon admission for treatment of AMI. Their CF6 levels peaked approximately 72 h after the onset of AMI and remained high for 7 days. At 7 days, their CF6 levels decreased to the level seen upon admission, but not to within a normal range. Hyperlipidemic patients had significantly greater CF6 levels at 24 h after onset of AMI than patients with a normal lipid profile. On admission, the plasma CF6 level in patients with a cardiac function of Killip class > or =II was higher than that in patients with a Killip class I cardiac function. At 3 days after the onset of AMI, the plasma CF6 levels of patients with a creatinine kinase (CK) peak value > or =1,500 units/l were significantly higher than those of patients with a CK peak value <1,500 units/l (p =0.05). At 7 days after the onset of AMI, the plasma CF6 levels of patients who received no reperfusion were significantly higher than those of patients who received a successful reperfusion. The plasma CF6 levels of AMI patients at admission, at 24 h, and at 3 days after onset of symptoms correlated positively with the cardiac function by Killip classification, respectively. At 24 h after onset of AMI, the plasma CF6 levels correlated positively with plasma total cholesterol levels and low-density lipoprotein levels. At 3 days, the plasma level of CF6 correlated positively with the plasma CK peak value and correlated negatively with left ventricular ejection fraction. These results suggest that the plasma CF6 level was elevated in patients with AMI.

Endothelin-1 is a potent regulator in vivo in vascular calcification and in vitro in calcification of vascular smooth muscle cells.

We observed changes of endothelin content and endothelin mRNA in vivo in vascular calcification and in vitro in calcification of vascular smooth muscle cells to explore the role of endothelin in vascular calcification. Calcification model in vivo was induced by administration of Vitamin D(3) plus nicotine. Calcification of vascular smooth muscle cells (VSMCs) was induced by beta-glycerophosphate. Endothelin content was measured by using radioimmunoassay. Endothelin mRNA amount was determined by using competitive quantitative RT-PCR. The results showed that calcium content, 45Ca(2+) uptake and alkaline phosphatase (ALP) activity were increased in calcified VSMCs, compared with controls, but were decreased, compared with calcified VSMCs plus BQ123 group. The endothelin content in the medium and endothelin mRNA in VSMCs were elevated by 35 and 120% (P<0.05), respectively, compared with those normal VSMCs. Calcium content, 45Ca(2+) accumulation and ALP activity in calcified arteries increased by 5.0-, 1.4-, and 1.4-fold. The endothelin levels in plasma and aorta as well as the amount of endothelin mRNA in calcified aorta were increased by 102, 103, and 22%, respectively, compared with control group. However, calcium content, 45Ca(2+) uptake and ALP activity in VDN plus bosentan group was 33, 36.7, and 40.4% lower than those in VDN group. These results indicated an upregulated endothelin gene expression as well as an increased production of endothelin in calcified aorta and VSMCs with BQ123 and bosentan significantly reducing vascular calcification. This suggested that endothelin might be involved in pathogenesis of vascular calcification.

Dysfunction of myocardial and vascular taurine transport in spontaneously hypertensive rats.

The alterations of taurine transport and the expression of taurine transporter (TAUT) mRNA in myocardium and aortic wall were investigated in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. It was demonstrated that plasma taurine concentration and taurine release from myocardium and aortic wall in SHR were higher than those in WKY rats, whereas taurine content, taurine uptake and TAUT mRNA in myocardium and aortic wall of SHR were lower than those of WKY rats. In SHR, the maximal velocity (V(max)) of taurine transportation in myocardium and aortic wall was lower by 24% (P<0.05) and 35% (P<0.05) than that in WKY, their michaelis constants (Km) values were higher by 16% (P<0.05) and 39% (P<0.05), respectively. The results suggest that there is dysfunction of taurine transport in myocardium and aortic wall in SHR, which may be partly resulted from the decrease of TAUT activity and affinity, and down-regulation of TAUT gene expression.

[Changes in adrenomedullin and receptor activity-modifying protein 2 mRNA in myocardium and vessels during L-NNA-induced hypertension in rats].

To explore the changes in adrenomedullin (ADM) and receptor activity-modifying protein 2 (RAMP2) mRNA in myocardium and vessels in hypertension, a hypertensive rat model was prepared by administering L-NNA. Contents of ADM in plasma, myocardium and vessels were measured by radioimmunoassay (RIA). The levels of pro-ADM mRNA of myocardium and vessels were determined by competitive quantitative RT-PCR. The results showed that L-NNA induced hypertension and cardiomegaly. The ratio of heart to body weight increased by 35.5% (P<0.01). In hypertensive rats the ir-ADM in plasma, myocardium and vessels was increased by 80%, 72% and 57% (P<0.01), respectively compared with the control. The amounts of ADM mRNA in myocardium and vessels were increased by 50% and 109.2% (P<0.05), respectively, and the amounts of RAMP2 mRNA was increased by 132% and 87% (P<0.01), respectively, compared with control. The levels of ADM in myocardium and vessels were positively correlated with RAMP2 mRNA, the correlation coefficients were 0.741 and 0.885 (P<0.01), respectively. The results obtained indicate that in hypertensive rats, ADM is elevated in plasma, myocardium and ves-myocardium and vessel, and ADM and RAMP2 mRNA are up-regulated in myocardium and vessel. The ADM/RAMP2 system may play an important role in the pathogenesis of hypertension.

Dysfunction of myocardial taurine transport and effect of taurine supplement in rats with isoproterenol-induced myocardial injury.

AIM: To study the alterations of myocardial taurine transport function, taurine transporter (TAUT), and cysteine sulfinate decarboxylase (CSD) mRNA as well as effect of exogenous taurine in rats with isoproterenol (ISO)-induced cardiomegaly. METHODS: [3H]-Taurine uptake and release on myocardium were determined. Binding sites of [3H]-taurine for myocardial sarcolemma were measured. TAUT and CSD mRNA levels were assayed using competitive quantitative reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: ISO group as compared with control group, myocardial taurine uptake markedly reduced, taurine release obviously increased; Bmax value of [3H]-taurine binding on cardiac sarcolemma reduced by 42% (P<0.05); TAUT and CSD mRNA levels decreased by 40% and 38% (P<0.05), respectively. ISO+taurine group as compared with ISO-treated group, the amounts of taurine uptake and TAUT mRNA returned to normal; taurine release reduced; Bmax increased by 92% (P<0.01), and CSD mRNA content augmented by 23% (P<0.05). There were no statistical differences of Kd values among the four groups (P>0.05). CONCLUSION: The data indicate that the failure to generate sufficient TAUT on myocardial sarcolemma may be the fundamental abnormality in ISO-induced cardiac injury. The mechanism by which administration of taurine considerably improves ISO-induced cardiac damage is probably to increase the expression of TAUT gene and recover taurine transport function.