Abstract-Chronic hypoxic pulmonary hypertension is associated with profound vascular remodeling and alterations in Ca 2ϩ homeostasis in pulmonary arterial smooth muscle cells (PASMCs). Recent studies show that transient receptor potential (TRPC) genes, which encode store-operated and receptor-operated cation channels, play important roles in Ca 2ϩ regulation and cell proliferation. However, the influence of chronic hypoxia on TRPC channels has not been determined. Here we compared TRPC expression, and store-and receptor-operated Ca 2ϩ entries in PASMCs of normoxic and chronic hypoxic rats. Reverse-transcription polymerase chain reaction (RT-PCR), Western blot, and immunostaining showed consistently that TRPC1, TRPC3, and TRPC6 were expressed in intralobar pulmonary arteries (PAs) and PASMCs. Application of 1-oleoyl-2-acetyl-sn-glycerol (OAG) to directly activate receptor-operated channels, or thapsigargin to deplete Ca 2ϩ stores, caused dramatic increase in cation entry measured by Mn 2ϩ quenching of fura-2 and by Ca 2ϩ transients. OAG-induced responses were Ϸ700-fold more resistant to La 3ϩ inhibition than thapsigargin-induced responses. siRNA knockdown of TRPC1 and TRPC6 specifically attenuated thapsigargin-and OAG-induced cation entries, respectively, indicating that TRPC1 mediates store-operated entry and TRPC6 mediates receptor-operated entry. In hypoxic PAs, there were 2-to 3-fold increases in TRPC1 and TRPC6 expression. They were accompanied by significant increases in basal, OAG-induced, and thapsigargin-induced cation entries in hypoxic PASMCs. Moreover, removal of Ca 2ϩ or inhibition of store-operated Ca 2ϩ entry with La 3ϩ and SK&F-96365 reversed the elevated basal [Ca 2ϩ ] i in PASMCs and vascular tone in PAs of chronic hypoxic animals, but nifedipine had minimal effects. Our results for the first time to our knowledge show that both store-and receptor-operated channels of PASMCs are upregulated by chronic hypoxia and contribute to the enhanced vascular tone in hypoxic pulmonary hypertension. Key Words: pulmonary hypertension Ⅲ transient receptor potential channels Ⅲ store-operated Ca 2ϩ channels Ⅲ receptor-operated Ca 2ϩ channels P rolonged exposure to alveolar hypoxia causes pulmonary hypertension with profound vascular remodeling and increase in vasomotor tone. The increase in vascular tone is in part attributable to alterations in vasoconstricting and vasorelaxing influences imposed by the endothelially derived and circulating factors. 1 Recent evidence indicates that chronic hypoxia also causes intrinsic changes in ionic balance and Ca 2ϩ homeostasis in pulmonary arterial smooth muscle cells (PASMCs), including membrane depolarization, elevation in resting [Ca 2ϩ ] i , and changes in electrophysiological and Ca 2ϩ responses to vasoconstrictors and vasodilators. [2][3][4][5][6] The mechanism for alteration in Ca 2ϩ homeostasis in hypoxic PASMCs is controversial. Previous studies found significant suppression of voltage-gated K ϩ (K V ) currents and K V channel expression in PASMCs isolated fr...

Abstract. Arctium lappa, commonly known as burdock, is being promoted/recommended as a healthy and nutritive food in Chinese societies. Burdock has been used therapeutically in Europe, North America and Asia for hundreds of years. The roots, seeds and leaves of burdock have been investigated in view of its popular uses in Traditional Chinese Medicine (TCM). In this review, the reported therapeutic effects of the active compounds present in the different botanical parts of burdock are summarized. In the root, the active ingredients have been found to "detoxify" blood in TCM term and promote blood circulation to the skin surface, improving the skin quality/texture and curing skin diseases like eczema. Antioxidants and anti-diabetic compounds have also been found in the root. In the seeds, some active compounds possess anti-inflammatory effects, and potent inhibitory effects on the growth of tumors such as the pancreatic carcinoma. In the leaf extract, the active compounds isolated can inhibit the growth of micro-organisms in the oral cavity. The medicinal uses of burdock in treating chronic diseases like cancers, diabetes and AIDS have been reported. However, it is also essential to be aware of the side-effects of burdock including contact dermatitis and other allergic/inflammatory responses that might be evoked by burdock.

+ -H+ exchange activity.3. Disrupting rafts by removal of cholesterol with methyl-b-cyclodextrin (MbCD) or destabilizing the actin cytoskeleton with cytochalasin D decreased the amount of NHE3 in early endosomes isolated by OptiPrep gradient fractionation. Specifically, NHE3 was shown to associate with endosomal vesicles immunoisolated by anti-EEA1 (early endosomal autoantigen 1) antibodycoated magnetic beads and the endosome-associated NHE3 was decreased by cytochalasin D and MbCD treatment.4. We conclude that: (i) a pool of ileal BB NHE3 exists in lipid rafts; (ii) EGF and clonidine increase the amount of BB NHE3; (iii) lipid rafts and to a lesser extent, the cytoskeleton, but not the detergent-soluble NHE3 pool, are involved in the EGF-and clonidine-induced acute increase in amount of BB NHE3; (iv) lipid rafts and the actin cytoskeleton play important roles in the basal endocytosis of BB NHE3.

Human equilibrative nucleoside transporter-3 (hENT3) was recently reported as a pH-dependent, intracellular (lysosomal) transporter capable of transporting anti-human immunodeficiency virus (HIV) dideoxynucleosides (ddNs). Because most anti-HIV ddNs (e.g., zidovudine, AZT) exhibit clinical mitochondrial toxicity, we investigated whether hENT3 facilitates transport of anti-HIV ddNs into the mitochondria. Cellular fractionation and immunofluorescence microscopy studies in several human cell lines identified a substantial presence of hENT3 in the mitochondria, with additional presence at the cell surface of two placental cell lines (JAR, JEG3). Mitochondrial or cell surface hENT3 expression was confirmed in human hepatocytes and placental tissues, respectively. Unlike endogenous hENT3, yellow fluorescent protein (YFP)-tagged hENT3 was partially directed to the lysosomes. Xenopus oocytes expressing NH2-terminal-deleted hENT3 (expressed at the cell surface) showed pH-dependent interaction with several classes of nucleosides (anti-HIV ddNs, gemcitabine, fialuridine, ribavirin) that produce mitochondrial toxicity. Transport studies in hENT3 gene-silenced JAR cells showed significant reduction in mitochondrial transport of nucleosides and nucleoside drugs. Our data suggest that cellular localization of hENT3 is cell type dependent and the native transporter is substantially expressed in mitochondria and/or cell surface. hENT3-mediated mitochondrial transport may play an important role in mediating clinically observed mitochondrial toxicity of nucleoside drugs. In addition, our finding that hENT3 is a mitochondrial transporter is consistent with the recent finding that mutations in the hENT3 gene cause an autosomal recessive disorder in humans called the H syndrome.

Recent studies show that three subtypes of RyRs are coexpressed and RyR-gated Ca 2ϩ stores are distributed heterogeneously in systemic vascular myocytes. However, the molecular identity and subcellular distribution of RyRs have not been examined in PASMCs. In this study we detected mRNA and proteins of all three subtypes in rat intralobar PASMCs using RT-PCR and Western blot. Quantitative real-time RT-PCR showed that RyR2 mRNA was most abundant, ϳ15-20 times more than the other two subtypes. Confocal fluorescence microscopy revealed that RyRs labeled with BODIPY TR-X ryanodine were localized in the peripheral and perinuclear regions and were colocalized with sarcoplasmic reticulum labeled with Fluo-5N. Immunostaining showed that the subsarcolemmal regions exhibited clear signals of RyR1 and RyR2, whereas the perinuclear compartments contained mainly RyR1 and RyR3. Ca 2ϩ sparks were recorded in both regions, and their activities were enhanced by a subthreshold concentration of caffeine or by endothelin-1, indicating functional RyR-gated Ca 2ϩ stores. Moreover, 18% of the perinuclear sparks were prolonged [full duration/half-maximum (FDHM) ϭ 193.3 Ϯ 22.6 ms] with noninactivating kinetics, in sharp contrast to the typical fast inactivating Ca 2ϩ sparks (FDHM ϭ 44.6 Ϯ 3.2 ms) recorded in the same PASMCs. In conclusion, multiple RyR subtypes are expressed differentially in peripheral and perinuclear RyR-gated Ca 2ϩ

Intestinal Cl− secretion is stimulated by cyclic AMP (cAMP) and intracellular calcium ([Ca2+]i). Recent studies show that protein kinase A (PKA) and the exchange protein directly activated by cAMP (Epac) are downstream targets of cAMP. Therefore, we tested whether both PKA and Epac are involved in forskolin (FSK)/cAMP-stimulated Cl− secretion. Human intestinal T84 cells and mouse small intestine were used for short circuit current (Isc) measurement in response to agonist-stimulated Cl− secretion. FSK-stimulated Cl− secretion was completely inhibited by the additive effects of the PKA inhibitor, H89 (1 µM), and the [Ca2+]i chelator, 1,2-bis-(o-aminophenoxy)-ethane-N,N,N’,N’-tetraacetic acid, tetraacetoxymethyl ester (BAPTA-AM; 25 µM). Both FSK and the Epac activator 8-pCPT-2’-O-Me-cAMP (50 µM) elevated [Ca2+]i, activated Ras-related protein 2, and induced Cl− secretion in intact or basolateral membrane–permeabilized T84 cells and mouse ileal sheets. The effects of 8-pCPT-2’-O-Me-cAMP were completely abolished by BAPTA-AM, but not by H89. In contrast, T84 cells with silenced Epac1 had a reduced Isc response to FSK, and this response was completely inhibited by H89, but not by the phospholipase C inhibitor U73122 or BAPTA-AM. The stimulatory effect of 8-pCPT-2’-O-Me-cAMP on Cl− secretion was not abolished by cystic fibrosis transmembrane conductance (CFTR) inhibitor 172 or glibenclamide, suggesting that CFTR channels are not involved. This was confirmed by lack of effect of 8-pCPT-2’-O-Me-cAMP on whole cell patch clamp recordings of CFTR currents in Chinese hamster ovary cells transiently expressing the human CFTR channel. Furthermore, biophysical characterization of the Epac1-dependent Cl− conductance of T84 cells mounted in Ussing chambers suggested that this conductance was hyperpolarization activated, inwardly rectifying, and displayed a Cl−>Br−>I− permeability sequence. These results led us to conclude that the Epac-Rap-PLC-[Ca2+]i signaling pathway is involved in cAMP-stimulated Cl− secretion, which is carried by a novel, previously undescribed Cl− channel.

BackgroundAngiogenesis plays an important role in a wide range of physiological processes, and many diseases are associated with the dysregulation of angiogenesis. Radix Astragali is a Chinese medicinal herb commonly used for treating cardiovascular disorders and has been shown to possess angiogenic effect in previous studies but its active constituent and underlying mechanism remain unclear. The present study investigates the angiogenic effects of calycosin, a major isoflavonoid isolated from Radix Astragali, in vitro and in vivo.Methodology Tg(fli1:EGFP) and Tg(fli1:nEGFP) transgenic zebrafish embryos were treated with different concentrations of calycosin (10, 30, 100 µM) from 72 hpf to 96 hpf prior morphological observation and angiogenesis phenotypes assessment. Zebrafish embryos were exposed to calycosin (10, 100 µM) from 72 hpf to 78 hpf before gene-expression analysis. The effects of VEGFR tyrosine kinase inhibitor on calycosin-induced angiogenesis were studied using 72 hpf Tg(fli1:EGFP) and Tg(fli1:nEGFP) zebrafish embryos. The pro-angiogenic effects of calycosin were compared with raloxifene and tamoxifen in 72 hpf Tg(fli1:EGFP) zebrafish embryos. The binding affinities of calycosin to estrogen receptors (ERs) were evaluated by cell-free and cell-based estrogen receptor binding assays. Human umbilical vein endothelial cell cultures (HUVEC) were pretreated with different concentrations of calycosin (3, 10, 30, 100 µM) for 48 h then tested for cell viability and tube formation. The role of MAPK signaling in calycosin-induced angiogenesis was evaluated using western blotting.ConclusionCalycosin was shown to induce angiogenesis in human umbilical vein endothelial cell cultures (HUVEC) in vitro and zebrafish embryos in vivo via the up-regulation of vascular endothelial growth factor (VEGF), VEGFR1 and VEGFR2 mRNA expression. It was demonstrated that calycosin acted similar to other selective estrogen receptor modulators (SERMs), such as raloxifene and tamoxifen, by displaying selective potency and affinity to estrogen receptors ERα and ERβ. Our results further indicated that calycosin promotes angiogenesis via activation of MAPK with the involvement of ERK1/2 and ER. Together, this study revealed, for the first time, that calycosin acts as a selective estrogen receptor modulator (SERM) to promote angiogenesis, at least in part through VEGF-VEGFR2 and MAPK signaling pathways.

The present study demonstrates that the contraction caused by PGE2 in the SHR aorta is dependent on the activation of EP1 and TP receptors, but that endothelium-dependent contractions do not require the former. Thus, PGE2 is unlikely to be an endothelium-derived contracting factor in this artery. The ability of AH6809 to inhibit endothelium-dependent contractions can be attributed to its partial antagonism at TP receptors. Nevertheless, the impairment of PGE2-mediated relaxation may contribute to endothelial dysfunction in the aorta of the SHR.