Involvement of calcium-sensing receptors in hypoxia-induced vascular remodeling and pulmonary hypertension by promoting phenotypic modulation of small pulmonary arteries.

Phenotype modulation of pulmonary artery smooth muscle cells (PASMCs) plays an important role during hypoxia-induced vascular remodeling and pulmonary hypertension (PAH). We had previously shown that calcium-sensing receptor (CaSR) is expressed in rat PASMCs. However, little is known about the role of CaSR in phenotypic modulation of PASMCs in hypoxia-induced PAH as well as the underlying mechanisms. In this study, we investigated whether CaSR induces the proliferation of PASMCs in small pulmonary arteries from both rats and human with PAH. PAH was induced by exposing rats to hypoxia for 7-21 days. The mean pulmonary arterial pressure (mPAP), right ventricular hypertrophy index (RVI), the percentage of medial wall thickness to the external diameter (WT %), and cross-sectional total vessel wall area to the total area (WA %) of small pulmonary arteries were determined by hematoxylin and eosin (HE), masson trichrome and Weigert's staining. The protein expressions of matrix metalloproteinase (MMP)-2 and MMP-9, the tissue inhibitors of metalloproteinase (TIMP)-3, CaSR, proliferating cell nuclear antigen (PCNA), phosphorylated extracellular signal-regulated kinase (p-ERK), and smooth muscle cell (SMC) phenotype marker proteins in rat small pulmonary arteries, including calponin, SMα-actin (SMAα), and osteopontin (OPN), were analyzed by immunohistochemistry and Western blotting, respectively. In addition, immunohistochemistry was applied to paraffin-embedded human tissues from lungs of normal human and PAH patients with chronic heart failure (PAH/CHF). Compared with the control group, mPAP, RVI, WT % and WA % in PAH rats were gradually increased with the prolonged hypoxia. At the same time, the expressions of CaSR, MMP-2, MMP-9, TIMP-3, PCNA, OPN, and p-ERK were markedly increased, while the expressions of SMAα and calponin were significantly reduced in lung tissues or small pulmonary arteries of PAH rats. Neomycin (an agonist of CaSR) enhanced but NPS2390 (an antagonist of CaSR) weakened these hypoxic effects. We further found that the expression change of CaSR, PCNA, and SMC phenotypic marker proteins in PAH/CHF lungs was similar to those in PAH rats. Our data suggest that CaSR is involved in the pulmonary vascular remodeling and PAH by promoting phenotypic modulation of small pulmonary arteries.

[Clinical efficacy of fire needling combined with cupping therapy on herpes zoster of acute stage and the effect on Th17/Treg cellular immune balance].

OBJECTIVE: To compare the clinical efficacy between the combined therapy of fire needling and cupping, and western medication on herpes zoster of acute stage, as well as the effects on Th17 and Treg cells and inflammatory factors, i.e. IL-10 and IL-17 in the peripheral blood. METHODS: Eighty patients with herpes zoster of acute stage were randomly divided into a combined therapy (fire needling plus cupping) group and a western medication group, 40 cases in each one. In the combined therapy group, the pricking and scattering techniques with fire needle were used at ashi points and Jiaji (EX-B 2) corresponding to the affected spinal segments; afterwards, cupping therapy was delivered. The combined treatment was given once daily. In the western medication group, valaciclovir hydrochloride tablet and vitamin B1 tablet were administered orally. The duration of treatment in each group was 10 days. Before each treatment from day 1 to day 10 and on day 11 , the score of symptoms and physical signs was observed in the two groups separately. Before each treatment from day 1 to day 10 and on day 11, 30, 60, the score of visual analogue scale (VAS) and skin lesion indexes were observed in the two groups. On day 60, the incidence of postherpetic neuralgia was recorded in the two groups. The levels of Th17 and Treg cells, Th17/Treg ratio in the peripheral blood, as well as serum levels of IL-10 and IL-17 were detected before and after treatment in the two groups. The clinical efficacy was compared between the two groups. RESULTS: From day 6 to day 10 during treatment and on day 11, the scores of symptoms and physical signs in the combined therapy group were lower than those of the western medication group (P<0.05, P<0.01). On day 3, day 6 to day 10 during treatment and day 11, day 30, VAS scores in the combined therapy group were lower than those of the western medication group (P<0.05, P<0.01). On day 60, the incidence of postherpetic neuralgia in the combined therapy group was lower compared with that in the western medication group (P<0.05). The blister arresting time and scabbing time in the combined therapy group were shorter than those of the western medication group (P<0.05). After treatment, the level of Th17, and Th17/Treg ratio in the peripheral blood, as well as the serum levels of IL-10 and IL-17 were all lower in comparison with those in the western medication group (P<0.05). The curative and remarkably effective rate was 82.5% (33/40) in the combined therapy group, higher than 62.5% (25/40) in the western medication group (P<0.05). CONCLUSION: The early application of fire needling combined with cupping therapy can effectively treat herpes zoster of acute stage, relieve pain, and reduce the incidence of postherpetic neuralgia, which may be related to reducing the levels of Th17 and Treg cells, and Th17/Treg ratio in the peripheral blood, as well as the serum levels of IL-10 and IL-17 so that the cellular immune balance is modulated.

Increased expression of calcium-sensing receptors in atherosclerosis confers hypersensitivity to acute myocardial infarction in rats.

Acute myocardial infarction (AMI) is a leading cause of death worldwide. Most cases of AMI result from coronary atherosclerosis (AS). The pathogenic mechanisms underlying AS lesions and AMI are incompletely understood. Calcium-sensing receptors (CaSR) belong to a family of G-protein-coupled receptors. We previously discovered that CaSR was expressed in the heart tissue of adult rats. CaSR may contribute to AMI in AS. We initially established a rat model of AS by injection of vitamin D(3) and feeding with a high-fat diet. Isoproterenol (ISO) was used to induce AMI. The MB isoenzyme of creatine kinase (CK-MB), lactate dehydrogenase (LDH), cardiac troponin T (cTnT), tetrazolium chloride staining, and cardiac function parameters were selected as indicators of myocardial damage or necrosis. Cardiac apoptosis was analyzed by transferase dUTP nick-end labeling (TUNEL) assay. Expression of CaSR, Bcl-2, Bax, caspase-3, p-ERK1/2, p-JNK, and p-p38 were determined by Western blot analysis. Compared with the control group, levels of cTnT, CK-MB, and LDH; number of TUNEL-positive cells; and expression of CaSR, Bax, caspase-3, p-ERK1/2, p-JNK and p-p38, were significantly increased, whereas cardiac function and expression of Bcl-2 were decreased markedly in isoproterenol (ISO)-treated group (C/ISO) and AS groups. These changes were significant in the AS/ISO group than in the C/ISO group or AS group. The upregulation of CaSR during AS formation renders hypersensitivity to AMI. Activation of the pro-apoptotic mitochondria pathway and JNK-p38 MAPK pathway triggered by increased expression of CaSR may be one of molecular mechanisms underlying AMI in AS.

Involvement of calcium-sensing receptor in oxLDL-induced MMP-2 production in vascular smooth muscle cells via PI3K/Akt pathway.

Matrix metalloproteinase-2 (MMP-2) is constitutively expressed in vascular smooth muscle cells (VSMCs) and up-regulated in atherosclerotic lesion by various stimuli, such as oxidized low-density lipoprotein (oxLDL). Calcium-sensing receptor (CaSR) is also expressed in VSMCs, but it remains unclear whether CaSR is associated with overproduction of MMP-2 in VSMCs. In this study, the expression of MMP-2 was detected by real-time PCR and Western blot analysis, and the gelatinolytic activity of MMP-2 was measured using gelatin zymography. Our results showed that oxLDL enhanced MMP-2 expression and activity in rat aortic VSMCs in a time- and dose-dependent manner. In addition, CaSR expression was up-regulated by oxLDL. Manipulating CaSR function in these cells by NPS2390 (an antagonist of CaSR) or GdCl(3) (an agonist of CaSR) affected the oxLDL-induced MMP-2 production. In VSMCs, oxLDL stimulated the rapid activation of phosphatidylinositol 3-kinase (PI3K)/Akt signal pathway, as determined by Western blot analysis. Phosphorylation of Akt and MMP-2 production stimulated by oxLDL were attenuated by LY294002 (a specific inhibitor of PI3K). Activation of Akt was suppressed by NPS2390 but enhanced by GdCl(3). In contrast, oxLDL had no stimulatory effect on the phosphorylation of JNK, and pretreatment with SP600125 (an inhibitor of JNK) produced no significant effect on oxLDL-induced MMP-2 production. These results suggest that CaSR mediates oxLDL-induced MMP-2 production in VSMCs via PI3K/Akt signal pathway.

SKF38393 prevents high glucose (HG)-induced endothelial dysfunction by inhibiting the effects of HG on cystathionine γ-lyase/hydrogen sulfide activity and via a RhoA/ROCK1 pathway.

BACKGROUND: Endothelial dysfunction plays a crucial role in diabetic vascular complications. A decrease in hydrogen sulfide (H2S) levels is increasingly becoming a vital factor contributing to high glucose (HG)-induced endothelial dysfunction. Dopamine D1-like receptors (DR1) activation has important physiological functions in the cardiovascular system. H2S decreases the dysfunction of vascular endothelial cells. However, no studies have reported whether DR1 protects the function of vascular endothelial cells by regulating H2S levels. AIM: The present study aimed to determine whether DR1 regulates the levels of endogenous H2S, which exerts protective effects against HG-induced injury of human umbilical vein endothelial cells (HUVECs) via Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil containing kinase 1 (ROCK1) signalling. METHODS: HUVECs were exposed to HG (30 mM) or normal glucose (5.5 mM) after different treatments. Cell viability, proliferation and migration were measured by Cell Counting Kit-8, EdU cell proliferation assay, transwell assay and wound healing assay, respectively. H2S probe (7-Azido-4-Methylcoumarin) was used to detect levels of H2S. The intracellular calcium concentration ([Ca2+]i) were measured using Fluo-4 AM. The protein expressions were quantified by Western blot. RESULTS: We found that HG decreased the expression of DR1 and cystathionine γ-lyase (CSE) and H2S production. The DR1 agonist SKF38393 significantly increased DR1 and CSE expression and H2S production, whereas NaHS (a H2S donor) only increased CSE expression and H2S production but had no effect on DR1 expression. Meanwhile, SKF38393 further increased the [Ca2+]i induced by HG. In addition, HG reduced cell viability and the expression of Cyclin D1 and proliferating cell nuclear antigen and increased the expression of p21C⁢i⁢p/W⁢A⁢F-1, collagen I, collagen III, matrix metalloproteinase 9, osteopontin and α-smooth muscle actin and the activity of phosphorylated RhoA and ROCK1. SKF38393 and NaHS reversed these effects of HG. PPG (a CSE inhibitor) abolished the beneficial effect of SKF38393. These effects of SKF38393 were similar to those of Y-27632 (a ROCK inhibitor). CONCLUSION: Taken together, our results suggest that DR1 activation upregulates the CSE/H2S pathway by increasing the [Ca2+]i, which protects endothelial cells from HG-induced injury by inhibiting the RhoA/ROCK1 pathway.

The functional expression of extracellular calcium-sensing receptor in rat pulmonary artery smooth muscle cells.

BACKGROUND: The extracellular calcium-sensing receptor (CaSR) belongs to family C of the G protein coupled receptors. Whether the CaSR is expressed in the pulmonary artery (PA) is unknown. METHODS: The expression and distribution of CaSR were detected by RT-PCR, Western blotting and immunofluorescence. PA tension was detected by the pulmonary arterial ring technique, and the intracellular calcium concentration ([Ca2+]i) was detected by a laser-scanning confocal microscope. RESULTS: The expressions of CaSR mRNA and protein were found in both rat pulmonary artery smooth muscle cells (PASMCs) and PAs. Increased levels of [Ca2+]o (extracellular calcium concentration) or Gd3+ (an agonist of CaSR) induced an increase of [Ca2+]i and PAs constriction in a concentration-dependent manner. In addition, the above-mentioned effects of Ca2+ and Gd3+ were inhibited by U73122 (specific inhibitor of PLC), 2-APB (specific antagonist of IP3 receptor), and thapsigargin (blocker of sarcoplasmic reticulum calcium ATPase). CONCLUSIONS: CaSR is expressed in rat PASMCs, and is involved in regulation of PA tension by increasing [Ca2+]i through G-PLC-IP3 pathway.

Role of dopamine D2 receptors in ischemia/reperfusion induced apoptosis of cultured neonatal rat cardiomyocytes.

BACKGROUND: Myocardial ischemia/reperfusion injury is the major cause of morbidity and mortality for cardiovascular diseases. Dopamine D2 receptors are expressed in cardiac tissues. However, the roles of dopamine D2 receptors in myocardial ischemia/reperfusion injury and cardiomyocyte apoptosis are unclear. Here we investigated the effects of both dopamine D2 receptors agonist (bromocriptine) and antagonist (haloperidol) on apoptosis of cultured neonatal rat ventricular myocytes induced by ischemia/reperfusion injury. METHODS: Myocardial ischemia/reperfusion injury was simulated by incubating primarily cultured neonatal rat cardiomyocytes in ischemic (hypoxic) buffer solution for 2 h. Thereafter, these cells were incubated for 24 h in normal culture medium. RESULTS: Treatment of the cardiomyocytes with 10 µM bromocriptine significantly decreased lactate dehydrogenase activity, increased superoxide dismutase activity, and decreased malondialdehyde content in the culture medium. Bromocriptine significantly inhibited the release of cytochrome c, accumulation of [Ca2+]i, and apoptosis induced by ischemia/reperfusion injury. Bromocriptine also down-regulated the expression of caspase-3 and -9, Fas and Fas ligand, and up-regulated Bcl-2 expression. In contrast, haloperidol (10 µM) had no significant effects on the apoptosis of cultured cardiomyocytes under the aforementioned conditions. CONCLUSIONS: These data suggest that activation of dopamine D2 receptors can inhibit apoptosis of cardiomyocytes encountered during ischemia/reperfusion damage through various pathways.

Downregulation of the ornithine decarboxylase/polyamine system inhibits angiotensin-induced hypertrophy of cardiomyocytes through the NO/cGMP-dependent protein kinase type-I pathway.

BACKGROUND: Polyamines and nitric oxide (NO) have been involved in the pathogenesis of cardiac hypertrophy. NO can regulate cardiac ion channels by direct actions on G-proteins and adenyl cyclase. The present study was undertaken to elucidate the molecular mechanism of interactions with polyamines and NO in cardiac hypertrophy. METHODS: Cardiaomyocyte hypertrophy was induced by angiotensinII (AngII). Hypertrophy was estimated by cell-surface area, atrial natriuretic peptide (ANP) mRNA expression, and the immunofluorescence of phalloidin. Pretreatment with alpha-difluoromethylornithine (DFMO) was done to deplete putrescine; KT5823 pretreatment was carried out to block the nitric oxide/cGMP-dependent protein kinase type-I (NO/PKG-I) pathway. Expressions of endothelial nitric oxide synthase (eNOS), PKG-I, c-fos and c-myc were analyzed by western blotting and immunofluorescence. The intracellular concentration of free calcium ([Ca2+](i)) was determined by confocal laser scanning microscopy. RESULTS: Hypertrophy of cardiomyocytes was induced by AngII, this caused an increase in putrescine, spermidine and total polyamine pool in association with a decreased level of NO. Expressions of eNOS and PKG-I were down-regulated, [Ca2+](i) was increased, and expressions of c-Fos and c-Myc upregulated. DFMO reversed these changes induced by AngII. CONCLUSIONS: Downregulation of polyamines inhibits cardiomyocyte hypertrophy, which is closely related to [Ca2+](i) and the NO/PKG-I pathway.

The functional expression of calcium-sensing receptor in the differentiated THP-1 cells.

The expression and function of calcium-sensing receptor (CaSR) in differentiated THP-1 (human acute monocytic leukemia cell line) cells are unknown currently. This study investigated above-mentioned issues using TRAP staining, immunofluorescence staining, Western blotting, ELISA, and Laser Confocal Scanning Microscopy techniques. We found that CaSR protein was expressed, and mainly located in the membrane and cytoplasm in differentiated THP-1 cells. Elevated extracellular calcium or GdCl(3) (an agonist of CaSR) raised intracellular calcium concentration. And this increase was inhibited or abolished by NPS2390 (an inhibitor of CaSR), U73122 (a specific inhibitor of phospholipase C, PLC) or thapsigargin (a Ca(2+)-ATPase inhibitor). The extracellular GdCl(3) elevation stimulated both of IL-1beta and TNFalpha release, and this effect of GdCl(3) was inhibited by NPS2390. In conclusion, CaSR is functionally expressed in differentiated THP-1 cells, and the activated CaSR contributes to intracellular calcium increment through Gq-PLC- inositol triphosphate (IP3) pathway and commits to cytokine secretion. These results suggest that CaSR might be involved in a variety of pathological processes mediated by activated monocyte-macrophages.

Increased expression of calcium-sensing receptors induced by ox-LDL amplifies apoptosis of cardiomyocytes during simulated ischaemia-reperfusion.

1. Acute myocardial infarction (AMI) is strongly associated with atherosclerosis, and is responsible for significant morbidity and mortality worldwide. The pathogenic mechanisms that underlie atherosclerosis and AMI are undefined at present. The calcium-sensing receptor (CaSR) is a member of the superfamily of G-protein coupled receptors. It has been demonstrated previously that the expression of CaSR is increased in atherosclerotic cardiac tissue of rats. It has also been suggested that CaSR has a crucial role in cardiac ischaemia-reperfusion injury, apoptosis and hypertrophy. However, it remains to be determined whether an increase in the expression of CaSR influences the sensitivity of cardiomyocytes to AMI. 2. The present study used cultured ventricular cardiomyocytes from neonatal rats to investigate the effect of oxidized low-density lipoprotein (ox-LDL), ischaemia-reperfusion, GdCl(3) (an agonist of CaSR) and NPS-2390 (an antagonist of CaSR) on the expression of CaSR. The amount of apoptosis, alterations in the morphology of the cells, the intracellular calcium concentration ([Ca(2+)](i)) and components of critical mitochondrial pathways were also analysed. 3. Cardiomyocytes treated with ox-LDL showed upregulated expression of CaSR, cytochrome c (cyt-c), Bax and activated caspase 3 (17 kD) and downregulated expression of Bcl-2, as well as elevated [Ca(2+)](i) and apoptosis. Application of GdCl(3) augmented these effects, and NPS-2390 decreased the expression of CaSR and reduced apoptosis. 4. In conclusion, ox-LDL was found to increase the expression of CaSR in a manner that was dependent on time and dose. It also augmented apoptosis during simulated ischaemia-reperfusion in cultured ventricular cardiomyocytes from neonatal rats.

[Professor LIN Guo-hua's experience in treatment of progressive muscular dystrophy with acupuncture].

Professor LIN Guo-hua's experience is introduced in treatment of progressive muscular dystrophy with acupuncture. It is believed that the pathogenesis of this disease is related to spleen and kidney deficiency, qi and blood insufficiency and malnutrition of tendon and muscle. The treatment is determined in terms of the pathogenesis and focuses on the regulation of spleen and kidney functions. The thinking of treatment is summarized as exerting the strong stimulation of acupuncture specially at the acupoints on the head, supplementing the sea of marrow, adjusting simultaneously the three yang meridians, rather than treating particularly yangming meridian and regulating qi in priority and considering the lung function for wei (flaccid) syndrome. Moreover, in clinical treatment, the acupoint thread-embedding therapy is commonly combined to ensure the significant therapeutic effect.

[Effects of exogenous H2S on hepatic fibrosis in diabetic mice and its mechanism].

OBJECTIVE: To investigate the effects of exogenous hydrogen sulfide (H2S) on the hepatic fibrosis in diabetic mice and its mechanism. METHODS: Twenty-four C57 male mice (weight 22±2 g) were randomly divided into three groups (n=8): ① Normal control group (Control): Mice were intraperitoneally injected equal amount of normal saline, the injection time was the same as that of the experimental groups; ② Diabetes model groups (HG): Streptozotocin (STZ) was injected intraperitoneally once according to body weight (150 mg/kg) to establish diabetes model; ③ NaHS treatment groups (HG + NaHS): Mice were intraperitoneally injected with NaHS (100 µmol/L·kg·d) once a day for 12 consecutive weeks. The hepatocyte injury was detected by HE staining; the hepatic fibrosis was observed through Masson staining; the protein expressions of cystathionine - ß - synthetase (CBS), collagen-I (CoL-I), collagen-III (CoL-III) and matrix metalloproteinase-9 (MMP-9) were detected by Western blot. RESULTS: Compared with the control group, the damage and fibrosis of hepatocyte were significantly aggravated, the expression of CBS proteins was decreased (P＜0.01), and the expression levels of CoL-I, CoL-III and MMP-9 proteins were increased (P＜0.01) in the diabetic model group. Compared with the diabetic model group, the damage and fibrosis of hepatocyte were significantly lightened, the expression of CBS proteins was obviously increased (P＜0.01), and the expression levels of CoL-I, CoL-III and MMP-9 proteins were markedly decreased (P＜ 0.01). CONCLUSION: H2S inhibits the hepatic fibrosis in diabetic mice, and its mechanism is related to the decrease of collagen and matrix metalloproteinase-9.

Involvement of the ornithine decarboxylase/polyamine system in precondition-induced cardioprotection through an interaction with PKC in rat hearts.

Polyamines (putrescine, spermidine, and spermine) play an essential role in cell growth, differentiation, and apoptosis. Protein kinase C (PKC) stimulates polyamine biosynthesis through the induction of ornithine decarboxylase (ODC), a rate-limiting enzyme in polyamine biosynthesis. Activation of PKC mediates ischemic preconditioning to reduce necrosis and apoptosis in intact hearts and in isolated culture cardiomyocytes. In this study, we examined whether the ODC/polyamine system is involved in the ischemic preconditioning signaling pathway and whether this system interacts with PKC in preconditioning-induced cardioprotection. Hearts were preconditioned with three cycles of 5-min ischemia and 5-min reflow, which caused an increase of ODC expression and spermidine, spermine, and total polyamine pool levels. alpha-Difluoromethylornithine (DFMO) and ethylglyoxal bis (guanylhydrazone) (EGBG) inhibited the key enzymes involved in polyamine biosynthesis, and abolished the preconditioning-induced reduction in infarct size and improvement in postischemic heart contractility function. They also increased cell apoptosis extent and aggravated myocardium ultrastructure damage. Inhibition also attenuated the preconditioning-induced translocation and activation of the PKC-delta, -epsilon isoforms from the cytosol to the particulate. Conversely, activation of PKC by phorbol 12-myristate 13-acetate (PMA) upregulated the ODC/polyamine system, whereas the PKC inhibitor chelerythrine (Che) downregulated the ODC/polyamine system. These findings suggest that upregulation of the polyamine synthesis metabolism occurs in response to preconditioning and mediates preconditioning-induced cardioprotection. The ODC/polyamine system and PKC signals may "cross-talk" in preconditioned hearts such that inhibiting one pathway leads to a reduction in the activity of the other pathway and vice versa.

Dopamine D2 receptor stimulation inhibits angiotensin II-induced hypertrophy in cultured neonatal rat ventricular myocytes.

1. Myocardial hypertrophy is a common pathological change that accompanies cardiovascular disease. Dopamine D2 receptors have been demonstrated in cardiovascular tissues. However, the pathophysiological involvement of D2 receptors in myocardial hypertrophy is unclear. Therefore, the effects of the D2 receptor agonist bromocriptine and the D2 receptor antagonist haloperidol on angiotensin (Ang) II- or endothelin (ET)-1-induced hypertrophy of cultured neonatal rat ventricular myocytes were investigated in the present study. 2. Protein content and protein synthesis, determined by examining [(3)H]-leucine uptake, were used as estimates of cardiomyocyte hypertrophy. The expression of D2 receptor protein in neonatal rat ventricular myocytes was determined using western blotting. Changes in [Ca(2+)](i) in cardiomyocytes were observed by laser scanning confocal microscopy. 3. Angiotensin II and ET-1, both at 10 nmol/L, induced myocyte hypertrophy, as demonstrated by increased protein content and synthesis, [Ca(2+)](i) levels, protein kinase C (PKC) activity and phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase and mitogen-activated protein kinase (MAPK) p38 (p38). Concomitant treatment of cells with 10 nmol/L AngII plus 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy, MAPK phosphorylation and PKC activity in the membrane, as well as [Ca(2+)](i) signalling pathways, compared with the effects of AngII alone. In addition, 10 micromol/L bromocriptine significantly inhibited cardiomyocyte hypertrophy induced by 10 nmol/L ET-1. However, pretreatment with haloperidol (10 micromol/L) had no significant effects on cardiomyocyte hypertrophy induced by either AngII or ET-1. 4. In conclusion, D2 receptor stimulation inhibits AngII-induced hypertrophy of cultured neonatal rat ventricular myocytes via inhibition of MAPK, PKC and [Ca(2+)](i) signalling pathways.

[Changes of myocardial function in diabetic rats and its mechanism].

OBJECTIVE: To investigate the role of calcium-sensing receptor (CaSR) in the decrease of cardiac function in type 2 diabetic rats. METHODS: Wistar rats were randomly divided into 3 groups including control, diabetic-4 week and diabetic-8 week groups. Rats in the diabetes group were fed with high-glucose and high-fat diet, and intraperitoneal injection of streptozocin (STZ,30 mg/kg) was conducted 4 weeks later to establish a type 2 diabetes model. Cardiac morphological changes were observed by HE staining, cardiac function was detected by echocardiography, and CaSR and PKC-αprotein expressions in cardiac tissue were detected by Western blot. RESULTS: Compared with the control group, the myocardium of diabetic rats showed irregular contraction zone, decreased expression of CaSR protein, increased expression of PKC-α protein, decreased systolic and diastolic functions, and gradually worsened with the prolongation of the course of the disease. CONCLUSION: Hyperglycemia inhibits the expression of CaSR protein in myocardium of diabetic rats by activating PKC-α, which can cause intracellular calcium disorder and lead to decreased cardiac function.

NPS2390, a Selective Calcium-sensing Receptor Antagonist Controls the Phenotypic Modulation of Hypoxic Human Pulmonary Arterial Smooth Muscle Cells by Regulating Autophagy.

BACKGROUND AND OBJECTIVES: Calcium-sensing receptor (CaSR) is known to regulate hypoxia-induced pulmonary hypertension (HPH) and vascular remodeling via the phenotypic modulation of pulmonary arterial smooth muscle cells (PASMCs) in small pulmonary arteries. Moreover, autophagy is an essential modulator of VSMC phenotype. But it is not clear whether CaSR can regulate autophagy involving the phenotypic modulation under hypoxia. METHODS: The viability of human PASMCs was detected by cell cycle and BrdU. The expressions of proliferation protein, phenotypic marker protein, and autophagy protein in human PASMCs were determined by western blot. RESULTS: Our results showed that hypoxia-induced autophagy was considerable at 24 h. The addition of NPS2390 decreased the expression of autophagy protein and synthetic phenotype marker protein osteopontin and increased the expression of contractile phenotype marker protein SMA-ɑ and calponin via suppressing downstream PI3K/Akt/mTOR signal pathways. CONCLUSIONS: Our study demonstrates that treatment of NPS2390 was conducive to inhibit the proliferation and reverse phenotypic modulation of PASMCs by regulating autophagy levels.

Involvement of calcium-sensing receptor in cardiac hypertrophy-induced by angiotensinII through calcineurin pathway in cultured neonatal rat cardiomyocytes.

Cardiac hypertrophy is a common pathological change accompanying cardiovascular disease. Recently, some evidence indicated that calcium-sensing receptor (CaSR) expressed in the cardiovascular tissue. However, the functional involvement of CaSR in cardiac hypertrophy remains unclear. Previous studies have shown that CaSR caused accumulation of inositol phosphate to increase the release of intracellular calcium. Moreover, Ca(2+)-dependent phosphatase calcineurin (CaN) played a vital role in the development of cardiac hypertrophy. Therefore, we investigated the expression of CaSR in cardiac hypertrophy-induced by angiotensin II (AngII) and the effects of CaSR activated by GdCl(3) on the related signaling transduction pathways. The results showed that AngII induced cardiac hypertrophy and up-regulated the expression of CaSR, meanwhile increased the intracellular calcium concentration ([Ca(2+)](i)) and activated CaN hypertrophic signaling pathway. Compared with AngII alone, the above changes were further obvious when adding GdCl(3). But the effects of GdCl(3) on the cardiac hypertrophy were attenuated by CsA, a specific inhibitor of CaN. In conclusion, these results suggest that CaSR is involved in cardiac hypertrophy-induced by AngII through CaN pathway in cultured neonatal rat cardiomyocytes.

[Increased myocardial expression of calcium-sensing receptor and apoptosis in a rat model of atherosclerosis].

OBJECTIVE: To observe the effect of hyperlipidemia and atherosclerosis on rat myocardial expression of calcium-sensing receptor and apoptosis. METHODS: The rat atherosclerosis model was induced by intraperitoneal injection of VD(3) (6 x 10(5) U/kg) and high cholesterol diet. Wistar rats were divided into two groups: (1) Control group; (2) AS group (n = 12 each). The expressions of CaSR, Bcl-2, Bax and caspase-3 were analyzed by Western blot and RT-PCR. Apoptotic cells were observed by TUNEL assay. The morphological changes of abdominal aorta and cardiac tissues were observed under optical and electro microscopes. The activity of LDH, CK, SOD and the content of MDA were assayed with ultraviolet spectrophotometer. The level of cTnT was detected by electrochemical immunofluorescence. RESULTS: Compared with control group, the activity of LDH and CK, the content of MDA and cTnT, the apoptosis index, the expression of CaSR, Bax and caspase-3 were significantly increased, but the SOD activity and Bcl-2 expression were significantly decreased, the myocardial ultrastructure injury was significantly aggravated in the AS group (all P < 0.05). CONCLUSION: Hyperlipidemia and atherosclerosis can up-regulate myocardial calcium-sensing receptor expression, promote myocardial apoptosis, aggravate oxidative stress and myocardial ischemia.

[Myocardial polyamine metabolism and the ischemia-reperfusion injury in the rat heart].

OBJECTIVE: To observe the polyamines metabolism changes in rat cardiomyocytes underwent ischemia-reperfusion (I/R) injury. METHODS: A branch of the descending left coronary artery was occluded to induce rat myocardial I/R injury (30 min ischemia followed by 2 h, 6 h, 12 h, and 24 h reperfusion). RT-PCR and Western blot were performed to detect the expression of spermidine/spermine N1-acetyltransferase (SSAT) and ornithine decarboxylase (ODC), the concentrations of polyamines were measured with high performance liquid chromatography in hearts with or without I/R. RESULTS: The myocardial transcription and expression of SSAT and ODC were significantly upregulated. Compared with the sham group, ODC mRNA and SSAT mRNA respectively increased 3.1 fold and 3.8 fold and their proteins respectively increased 3.1 fold and 2.9 fold at 24 h of reperfusion (P < 0.01); the concentrations of spermidine, spermine and the total polyamine pool respectively decreased by 33.6%, 35.3% and 32.9% while putrescine concentration increased by 58.9% at 24 h of reperfusion (P < 0.01). CONCLUSION: Our results suggest that ischemia-reperfusion in the heart may affect polyamine metabolism and the disturbance of polyamine metabolism might thus play a critical role in myocardial I/R injury in this model.

[Protective effects of exogenous H2S to the recovery of hypoxia post-conditioning on aged H9C2 cells and the underling mechanisms].

OBJECTIVE: To investigate the recovery of protective effects of exogenous hydrogen sulfide (H2S) on hypoxia post-conditioning in aged H9C2 cells and its mechanism. METHODS: H9C2 cells (cardiomyocytes line) were treated with 30 µmol/L hydrogen peroxide (H2O2) for 2 hours, then cultured for 3 days in order to induce cellular aging. Aged H9C2 cells were randomly divided into 5 groups (n=8):Control group (Control), hypoxia/reoxygenation group (H/R), H/R + NaHS group, hypoxia post-conditioning (PC) group, PC+NaHS group. H/R model:the cells were exposed to hypoxic culture medium (serum and sugar free medium, pH=6.8) for 3 hours and then cultured at normal condition for 6 hours. PC model:at the end of hypoxia for 3 hours, the cells were exposed to normoxic culture solution for 5 minutes, then the cells were placed in hypoxic solution for 5 minutes, the cycle above-mentioned was repeated 3 times and followed by reoxygenation for 6 hours. Advanced glycation end products (AGEs) content and caspase-3 activity were detected by ELISA. The cell viability was observed by cell counting kit-8 (CCK-8). The reactive oxygen species (ROS) levels were analyzed using 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA) staining. The apoptotic rate was determined through Hoechst 33342 staining. The mRNA levels of relative gene expression were detected by real-time PCR. RESULTS: Thirty µmol/L H2O2 induced H9C2 cell senescence while did not lead to apoptosis. Compared with control group, cell viability was decreased, the apoptotic rate、levels of ROS and the mRNA of caspase-3, caspase-9 and Bcl-2 were increased in H/R and PC groups (P<0.01). There were no differences in the above indexes between PC group and H/R group. Supplementation of NaHS increased cell viability and decreased apoptotic rate and oxidative stress. The effects of PC + NaHS on the above indexes were better than those of H/R+NaHS group. CONCLUSIONS: Exogenous H2S can restore the protective effect of PC on the aged H9C2 cells, and its mechanism is related to the inhibition of oxidative stress and apoptosis.