Biomedical subjects

Jie Li

Publications and source records attributed to Jie Li.

At least 145 records · Page 8Linked to original sources

PubMed2005

Depletion of 4-hydroxynonenal in hGSTA4-transfected HLE B-3 cells results in profound changes in gene expression.

Previously, we have shown that overexpression of 4-hydroxy-2-nonenal (HNE)-detoxifying enzyme glutathione S-transferase A4-4 (hGSTA4-4) in human lens epithelial cells (HLE B-3) leads to pro-carcinogenic phenotypic transformation of these cells [R. Sharma, et al. Eur. J. Biochem. 271 (2004) 1960-1701]. We now demonstrate that hGSTA4-transfection also causes a profound change in the expression of genes involved in cell adhesion, cell cycle control, proliferation, cell growth, and apoptosis, which is consistent with phenotypic changes of the transformed cells. The expression of p53, p21, p16, fibronectin 1, laminin gamma1, connexin 43, Fas, integrin alpha6, TGFalpha, and c-jun was down-regulated, while the expression of protein kinase C beta II (PKCbetaII), c-myc, cyclin-dependent kinase 2 (CDK2), and TGFbeta was up-regulated in transfected cells. These results demonstrate that HNE serves as a crucial signaling molecule and, by modulating the expression of genes, can influence cellular functions.

Aldehydes↗

PubMed2005

The gonadotropin-regulated long-chain acyl CoA synthetase gene: a novel downstream Sp1/Sp3 binding element critical for transcriptional promoter activity.

The 79 kD gonadotropin-regulated testicular long chain acyl-CoA synthetase gene (GR-LACS) is a hormone-regulated member of the acyl-CoA synthetase family that is expressed abundantly in Leydig cells and to a lesser extent in germinal cells of the adult testis. GR-LACS possesses an ATP/AMP binding domain and the fatty acyl-CoA synthetase (FACS) signature motif. To gain insights into the transcriptional regulation of GR-LACS in gonadal cells, we determined the genomic organization of the gene, including the upstream flanking sequences. The mouse GR-LACS gene spans over at least 45 kb and the coding region is encoded by exons 1-14. All exon-intron junction sites correspond to the consensus splice sequence GT-AG. Exon 7 and 11 comprise the conserved ATP/AMP binding domain and the FACS signature motif, respectively. Primer extension and S1 nuclease analyses demonstrated four transcriptional start sites located at -266/-216 bp 5' to the ATG codon. The minimal promoter domain resides within -254/-217 bp 5' to ATG codon, and upstream sequences to -404 bp (-1035/-405 bp) contribute to the inhibition of transcription in the expressing mouse Leydig tumor cells. Removal of -217/-1 bp, containing a 23 nt GC rich sequence (-112/-90) with an Sp1/Sp3 binding element, within the 1st exon of this TATA-less promoter, significantly reduced GR-LACS gene transcription. Transcriptional activity was abolished by a 2 nt mutation of this element. Thus, functional analyses of this promoter domain indicate that transcription of GR-LACS gene requires an Sp1/Sp3 binding element downstream of the transcriptional start sites which is essential for basal promoter activity.

Animals↗

PubMed2005

Boson peak in supercooled liquids: time domain observations and mode coupling theory.

Optical heterodyne-detected optical Kerr effect (OHD-OKE) experiments are presented for the supercooled liquid acetylsalicylic acid (aspirin - ASP). The ASP data and previously published OHD-OKE data on supercooled dibutylphthalate (DBP) display highly damped oscillations with a periods of approximately 2 ps as the temperature is reduced to and below the mode coupling theory (MCT) temperature T(C). The oscillations become more pronounced below T(C). The oscillations can be interpreted as the time domain signature of the boson peak. Recently a schematic MCT model, the Sjogren model, was used to describe the OHD-OKE data for a number of supercooled liquids by Gotze and Sperl [W. Gotze and M. Sperl, Phys. Rev. E 92, 105701 (2004)] , but the short-time and low-temperature behaviors were not addressed. Franosch et al. [T. Franosch, W. Gotze, M. R. Mayr, and A. P. Singh, Phys. Rev. E 55, 3183 (1997)] found that the Sjogren model could describe the boson peak observed by depolarized light-scattering (DLS) experiments on glycerol. The OHD-OKE experiment measures a susceptibility that is a time domain equivalent of the spectrum measured in DLS. Here we present a detailed analysis of the ASP and DBP data over a broad range of times and temperatures using the Sjogren model. The MCT schematic model is able to describe the data very well at all temperatures and relevant time scales. The trajectory of MCT parameters that fit the high-temperature data (no short-time oscillations) when continued below T(C) results in calculations that reproduce the oscillations seen in the data. The results indicate that increasing translational-rotational coupling is responsible for the appearance of the boson peak as the temperature approaches and drops below T(C).

Journal Article↗

PubMed2005

Thioredoxin-like domain of human kappa class glutathione transferase reveals sequence homology and structure similarity to the theta class enzyme.

Glutathione transferases (GSTs) are a superfamily of enzymes that play a vital functional role in the cellular detoxification process. They catalyze the conjugation of the thiol group of glutathione (GSH) to the electrophilic groups of a wide range of hydrophobic substrates, leading to an easier removal of the latter from the cells. The kappa class is the least studied one among various classes within the superfamily. We report here the expression, purification, and crystal structure of human kappa class GST (hGSTK), which has been determined by the multiple-isomorphous replacement method and refined to 1.93 A resolution. The overall structure of hGSTK is similar to the recently reported structure of kappa class GST from rat mitochondrion. Each subunit of the dimeric hGSTK contains a thioredoxin (TRX)-like domain and a helical domain. A molecule of glutathione sulfinate, an oxidized product of GSH, is found to bind at the G site of each monomer. One oxygen atom of the sulfino group of GSF forms a hydrogen bond with the hydroxyl group of the catalytic residue Ser16. The TRX-like domain of hGSTK shares 19% sequence identity and structure similarity with human theta class GST, suggesting that the kappa class of GST is more closely related to the theta class enzyme within the GST superfamily. The structure of the TRX-like domain of hGSTK is also similar to that of glutathione peroxidase (GPx), implying an evolutionary relationship between GST and GPx.

Amino Acid Sequence↗

PubMed2005

Detection of the nucleocapsid protein of severe acute respiratory syndrome coronavirus in serum: comparison with results of other viral markers.

A capture enzyme-enhanced chemiluminescence immunoassay (ECLIA) based on three specific monoclonal antibodies to detect the nucleocapsid (N) protein of severe acute respiratory syndrome (SARS) associated coronavirus (SARS-CoV) in the serial serum samples from SARS patients was developed. The anti-SARS-CoV IgG and the viral RNA were also detected in the sera by ELISA and RT-PCR, respectively. During the first 10 days after onset, anti-SARS-CoV IgG, SARS-CoV RNA and the N protein were detected in 21.4, 42.9, and 90% of the patients' sera, respectively. The detection rate of the N protein during days 11-15 of the disease was still significantly higher than those of anti-SARS-CoV IgG and SARS-CoV RNA. The data demonstrated that detection of the N protein with the capture ECLIA appears to be more useful than detection of other viral makers for rapid diagnosis of SARS in patients.

Adult↗

PubMed2005

Tuning the regioselectivity of the Staudinger reaction for the facile synthesis of kanamycin and neomycin class antibiotics with N-1 modification.

[reaction: see text] A novel method for achieving the desired regioselective reduction of the N-1 azido group on a tetraazidoneamine has been developed that leads to the synthesis of both kanamycin and neomycin class antibiotics bearing N-1 modification. Both classes of aminoglycosides are active against aminoglycoside-resistant bacteria carrying APH(3')-I and AAC(6')/APH(2'').

Amikacin↗

PubMed2005

Treatment for liver metastases from breast cancer: results and prognostic factors.

AIM: Liver metastases from breast cancer (BCLM) are associated with poor prognosis. Cytotoxic chemotherapy can result in regression of tumor lesions and a decrease in symptoms. Available data, in the literature, also suggest a subgroup of patients may benefit from surgery, but few talked about transcatheter arterial chemoembolization (TACE). We report the results of TACE and systemic chemotherapy for patients with liver metastases from breast cancer and evaluate the prognostic factors. METHODS: Forty-eight patients with liver metastases, from proved breast primary cancer were treated with TACE or systemic chemotherapy between January 1995 and December 2000. Treatment results were assessed according to WHO criteria, along with analysis of prognostic factors for survival using Cox regression model. RESULTS: The median follow-up was 28 mo (1-72 mo). Response rates were calculated for the TACE group and chemotherapy group, being 35.7% and 7.1%, respectively. The difference was significant. The one-, two- and three-year Survival rates for the TACE group were 63.04%, 30.35%, and 13.01%, and those for the systemic chemotherapy group were 33.88%, 11.29%, and 0%. According to univariate analysis, variables significantly associated with survival were the lymph node status of the primary cancer, the clinical stage of liver metastases, the Child-Pugh grade, loss of weight. Other factors such as age, the intervals between the primary to the metastases, the maximal diameter of the liver metastases, the number of liver metastases, extrahepatic metastasis showed no prognostic significances. These factors mentioned above such as the lymph node status of the primary cancer, the clinical stage of liver metastases, the Child-Pugh grade, loss of weight were also independent factors in multivariate analysis. CONCLUSION: TACE treatment of liver metastases from breast cancer may prolong survival in certain patients. This approach offers new promise for the curative treatment of the patients with metastatic breast cancer.

Adult↗

PubMed2005

Proteins and protein pattern differences between glioma cell lines and glioblastoma multiforme.

INTRODUCTION: Research into the pathogenesis, molecular signaling, and treatment of glioblastoma multiforme (GBM) has traditionally been conducted using cell lines derived from malignant gliomas. We compared protein expression patterns between solid primary GBMs and GBM cell lines to identify proteins whose expression may be altered in cell culture. METHODS: We cultured cell lines U87, U118, U251, and A172 and used tissue-selective microdissection of eight primary GBMs to obtain pure populations of tumor cells, which we studied using two-dimensional gel electrophoresis (2DGE) and examined using differential expression software. Select protein targets expressed differentially between GBM tumors and GBM cell lines were sequenced using tandem mass spectrometry. RESULTS: Analysis of the primary GBM tumor samples (n = 8) and the GBM cell lines revealed reproducibly similar proteomic patterns for each group, which distinguished tumors from the cell lines. Gels contained up to 500 proteins that were consistently identified in the pH 4 to 7 range. Comparison of proteins identified in the GBM tumors and in the cell lines showed approximately 160 proteins that were gained and 60 proteins that were lost on culture. Using normalized intensity patterns from the 2DGE images, ANOVA tests were done and statistically significant spots were identified. Seven proteins found in the cell lines were significantly increased when compared with the GBM tumors (P < 0.05), whereas 10 proteins were significantly decreased from cell lines compared with the GBM tumors. Proteins identified included transcription factors, tumor suppressor genes, cytoskeletal proteins, and cellular metabolic proteins. CONCLUSION: Global protein and proteomic differences were identified between primary GBM tumor samples and GBM cell lines. The proteins identified by 2DGE analysis elucidate some of the selection pressures of in vitro culture, help accentuate the advantages and limitations of cell culture, and may aid comprehension of gliomagenesis and enhance development of new therapeutics.

Brain Neoplasms↗

PubMed2005

Ultrafast to slow orientational dynamics of a homeotropically aligned nematic liquid crystal.

The orientational dynamics of a homeotropically aligned nematic liquid crystal, 4'-pentyl-4-biphenylcarbonitrile (5-CB), is studied over more than six decades of time (500 fs to 2 mus) using optical heterodyne detected optical Kerr effect experiments. In contrast to the dynamics of nematogens in the isotropic phase, the data do not decay as a highly temperature-dependent exponential on the longest time scale, but rather, a temperature-independent power law spanning more than two decades of time, the final power law, is observed. On short time scales (approximately 3 ps to approximately 1 ns) another power law, the intermediate power law, is observed that is temperature dependent. The power law exponent of the correlation function associated with the intermediate power law displays a linear dependence on the change in the nematic order parameter with temperature. Between the intermediate power law and the final power law, there is a crossover region that displays an inflection point. The temperature-dependent orientational dynamics in the nematic phase are shown to be very different than those observed in the isotropic phase.

Journal Article↗

PubMed2005

Allelic imbalance of chromosome 1q in esophageal squamous cell carcinomas from China: a novel region of allelic loss and significant association with differentiation.

Our previous work has shown that a number of genes locating on 1q21 were down-regulated in esophageal squamous cell carcinomas (ESCC) and they may involve in carcinogenesis. To determine whether chromosome 1q LOH occurs in ESCC, we analyzed LOH in 61 ESCCs using 18 microsatellite markers on chromosome 1q. Forty-six of 61 (75.4%) tumors presented LOH at one or more loci. A significant association was found between chromosome 1q LOH and histopathological grade. LOH on D1S3466 had a negative correlation with family history, whereas LOH on D1S2777 positively correlated with smoking. These results suggest this region harbor putative tumor suppressor gene(s) contributing to tumorigenesis and differentiation in ESCC.

Aged↗

PubMed2005

[Successful preimplantation genetic diagnosis for beta-thalassemia using multiplex nested polymerase chain reaction].

OBJECTIVE: To develop single-cell multiplex nested polymerase chain reaction (PCR) assays for preimplantation genetic diagnosis (PGD) in couples at risk of having child with beta-thalassemia. METHODS: Primers were designed and synthesized according to the documented mutation sites common among Chinese. Venous blood was collected from 4 pairs of husband and wife, all heterozygotes for beta-thalassemia, and underwent multiple nested PCR. Intraooplasmic sperm injection and mechanical bio psy was used to obtain single blastomere. Multiplex nested PCR was used to detect the CD41-42 mutation and the closely linked polymorphic marker, HumTHO1 gene or CD41-42, CD41-28, IVSII654 mutation and HumTHO1 gene in the single blastomeres from four clinical PGD cycles. The normal embryos with high scores capable of continuing to divide were transplanted into the uteri. The process of gestation was observed. RESULTS: 200 lymphocytes were amplified by nested PCR. The average amplification rate of the most common 16 beta-thalassemia mutations in Chinese population was 91.3% and the average rate of allele drop out for different sites was 17.0% without differences between any 2 sites. During the 4 PGD cycles 33 embryos underwent bioassay with a success rate of 100%. 33 blastomeres were obtained to undergo PCR, of which 30 were successfully amplified with an amplification rate of 90.9%. Explicit diagnosis was obtained in 26 of the 30 embryos: 7 normal homozygotes, 11 heterozygotes, and 8 abnormal or complex heterozygotes. One or more embryos were transferred back into the uteri of the 4 women and clinical pregnancy occurred in one woman. Five weeks after the implantation B-mode ultrasonography showed monocyesis, and in the 17th week of gestational period paracentesis of cord blood showed normal homozygote. At last a normal female infant confirming the PGD result had been born, which was the first reported unaffected pregnancy resulting from PGD using multiplex nested PCR for couples as beta-thalassemia gene carriers. The results of diagnosis for embryo all corresponded to those for blastomere. The average ADO rate of blastomere was 13.3% (4/30). CONCLUSION: PGD using multiplex nested PCR, as an alternative to prenatal diagnosis, is a reliable and effective way to help couples-carriers of pathogenetic genes to get a healthy baby.

Adult↗

PubMed2005

Generation of PRL-3- and PRL-1-specific monoclonal antibodies as potential diagnostic markers for cancer metastases.

PURPOSE: The PRL-3 mRNA is consistently elevated in metastatic samples derived from colorectal cancers. We sought to generate a specific PRL-3 monoclonal antibody (mAb) that might serve as a potential diagnostic marker for colorectal cancer metastasis. EXPERIMENTAL DESIGN: PRL-3 is one of three members (PRL-1, PRL-2, and PRL-3) in a unique protein-tyrosine phosphatase family. Because the three PRLs are 76% to 87% identical in their amino acid sequences, it poses a great challenge to obtain mAbs that are specific for respective phosphatase of regenerating liver (PRL) but not for the other two in the family. We screened over 1,400 hybridoma clones to generate mAbs specific to each PRL member. RESULTS: We obtained two hybridoma clones specifically against PRL-3 and another two clones specifically against PRL-1. These antibodies had been evaluated by several critical tests to show their own specificities and applications. Most importantly, the PRL-3 mAbs were assessed on 282 human colorectal tissue samples (121 normal, 17 adenomas, and 144 adenocarcinomas). PRL-3 protein was detected in 11% of adenocarcinoma samples. The PRL-3- and PRL-1-specific mAbs were further examined on 204 human multiple cancer tissues. The differential expressions of PRL-3 and PRL-1 confirmed the mAbs' specificity. CONCLUSIONS: Using several approaches, we show that PRL-3- or PRL-1-specific mAbs react only to their respective antigen. The expression of PRL-3 in >10% of primary colorectal cancer samples indicates that PRL-3 may prime the metastatic process. These mAbs will be useful as markers in clinical diagnosis for assessing tumor aggressiveness.

Adenocarcinoma↗

PubMed2005

Retinal degeneration 12 (rd12): a new, spontaneously arising mouse model for human Leber congenital amaurosis (LCA).

PURPOSE: To report the phenotype and characterization of a new, naturally occurring mouse model of hereditary retinal degeneration (rd12). METHODS: The retinal phenotype of rd12 mice were studied using serial indirect ophthalmoscopy, fundus photography, electroretinography (ERG), genetic analysis including linkage studies and gene identification, immunohistochemistry, and biochemical analysis. RESULTS: Mice homozygous for the rd12 mutation showed small punctate white spots on fundus examination at 5 months of age. The retina in the rd12 homozygote had a normal appearance at the light microscopic level until 6 weeks of age when occasional voids appeared in the outer segments (OS) of the photoreceptor (PR) cells. The outer nuclear layer (ONL) appeared normal until 3 months of age though more obvious voids were detected in the OS. By 7 months of age, 6 to 8 layers of ONL remained in the mutant retina, and the OS were obviously shorter. The first sign of retinal degeneration was detected at the electron microscopic level around 3 weeks of age when occasional small lipid-like droplets were detected in the retinal pigment epithelium (RPE). By 3 months of age, much larger, lipid-like droplets accumulated in RPE cells accompanied by some OS degeneration. While the histology indicated a relatively slow retinal degeneration in the rd12 homozygous mutant mice, the rod ERG response was profoundly diminished even at 3 weeks of age. Genetic analysis showed that rd12 was an autosomal recessive mutation and mapped to mouse chromosome 3 closely linked to D3Mit19, a location known to be near the mouse Rpe65 gene. Sequence analysis showed that the mouse retinal degeneration is caused by a nonsense mutation in exon 3 of the Rpe65 gene, and the gene symbol for the rd12 mutation has been updated to Rpe65rd12 to reflect this. No RPE65 expression, 11-cis retinal, or rhodopsin could be detected in retinas from rd12 homozygotes, while retinyl esters were found to accumulate in the retinal pigment epithelium (RPE). CONCLUSIONS: Mutations in the retinal pigment epithelium gene encoding RPE65 cause an early onset autosomal recessive form of human retinitis pigmentosa, known as Leber congenital amaurosis (LCA), which results in blindness or severely impaired vision in children. A naturally arising mouse Rpe65 mutation provides a good model for studying the pathology of human RPE65 mutations and the effects of retinyl ester accumulation.

Animals↗

PubMed2005

[Detection of blood dissemination during the operation of lung cancer and its significance].

OBJECTIVE: To evaluate the possibility of dissemination of lung cancer cells through blood during the operation for lung cancer. METHODS: The blood samples were taken from 52 patients with non-small cell lung cancer (NSCLC) and 5 patients with benign lung diseases at four different intervals during the operation. The transcription of carcinoembryonic antigen (CEA) messenger ribonucleic acid was assayed by means of nested reverse transcriptase polymerase chain reaction (RT-PCR). A549 (a human adenocarcinoma cell line) served as positive control. The sensitivity has been tested using quantificationally diluted A549 cells. RESULTS: The CEA mRNA positive rates of all four time spots are as follows: 31% (16/52) at beginning of the operation (sample taken from peripheral vein), 54% (28/52) at ligating the pulmonary vein (peripheral vein), 54% (28/52) at ligating the pulmonary vein (pulmonary vein) and 54% (28/52) at 1 hour after ligating the pulmonary vein (peripheral vein). There is no relationship between the tumor identity and the positive rate of CEA mRNA. The positive rate of CEA mRNA is higher in patients with centrally located lung cancer than that in patients with peripherally located lung cancer, similar phenomenon is also found between patients with advanced lung cancer and the patients with early stage of lung cancer. No negative control samples was found to be positive for CEA mRNA, the sensitivity of our test was 1 x 10(-6). CONCLUSIONS: The cancer cell dissemination during operation was demonstrated indirectly in our study, the time of pulmonary vein ligation (later or earlier) may affect the quantity of tumor cells released into circulation. Patients with lung cancer of central type and late TNM stage have more possibility of cancer cell dissemination during operation. More effective means may be needed to avoid the dissemination of cancer cells.

Adult↗

PubMed2005

Tumor susceptibility of Rassf1a knockout mice.

The human Ras association domain family 1 (RASSF1) gene is located at 3p21.3 in an area that is believed to harbor at least one important tumor suppressor gene. The two major isoforms of RASSF1, RASSF1A and RASSF1C, are distinguished by alternative NH(2)-terminal exons and the two transcripts initiate in two separate CpG islands. RASSF1A is one of the most frequently inactivated genes described thus far in human solid tumors. Inactivation of RASSF1A most commonly involves methylation of the promoter and CpG island associated with the RASSF1A isoform. In contrast, RASSF1C is almost never inactivated in tumors. Here, we have derived Rassf1a knockout mice in which exon 1-alpha of the Rassf1 gene was deleted, leading to specific loss of Rassf1a but not Rassf1c transcripts. Rassf1a-targeted mice were viable and fertile. Rassf1a(-/-) mice were prone to spontaneous tumorigenesis in advanced age (18-20 months). Whereas only two tumors developed in 48 wild-type mice, six tumors were found in 35 Rassf1a(+/-) mice (P < 0.05) and thirteen tumors were found in 41 Rassf1a(-/-) mice (P < 0.001). The tumors in Rassf1a-targeted mice included lung adenomas, lymphomas, and one breast adenocarcinoma. Rassf1a(-/-) and wild-type mice were treated with two chemical carcinogens, benzo(a)pyrene and urethane, to induce skin tumors and lung tumors, respectively. Rassf1a(-/-) and Rassf1a(+/-) mice showed increased tumor multiplicity and tumor size relative to control animals. The data are consistent with the tumor-suppressive role of Rassf1a, which may explain its frequent epigenetic inactivation in human tumors.

Adenocarcinoma↗

PubMed2005

Cre-mediated recombination in cell lineages that express the progesterone receptor.

Using gene-targeting methods, a progesterone receptor Cre knockin (PR-Cre) mouse was generated in which Cre recombinase was inserted into exon 1 of the PR gene. The insertion positions the Cre gene downstream (and under the specific control) of the endogenous PR promoter. As for heterozygotes for the progesterone receptor knockout (PRKO) mutation, mice heterozygous for the Cre knockin insertion are phenotypically indistinguishable from wildtype. Crossing the PR-Cre with the ROSA26R reporter revealed that Cre excision activity is restricted to cells that express PR in progesterone-responsive tissues such as the uterus, ovary, oviduct, pituitary gland, and mammary gland. Initial characterization of the PR-Cre mouse underscores the utility of this model to precisely ablate floxed target genes specifically in cell lineages that express the PR. In the wider context of female reproductive tissue ontology, this model will be indispensable in tracing the developmental fate of cell lineages that descend from PR positive progenitors.

Animals↗

PubMed2005

Effect of the 1,450 nm diode non-ablative laser on collagen expression in an artificial skin model.

BACKGROUND AND OBJECTIVE: The 1,450-nm Smoothbeam Laser is a diode laser equipped with a cryogen cooling spray. Primary objectives were to evaluate the effects of this non-ablative laser on Apligraf (bioengineered skin-substitute) and to document its use as a model for non-ablative procedures. We also measured the effects of laser fluence levels on collagen and elastin expression. STUDY DESIGN/MATERIALS AND METHODS: Three sheets of Apligraf were used for this study. Each received six separate laser applications at 4J, 6J, 8J, 10 J, 12J, and 14J. The sheets were then incubated with 10% CO(2) at 37 degrees C and samples were collected and analyzed 3 days later, using RT-PCR and immunofluorescent staining. RESULTS: Collagen III expressions significantly increased in both mRNA and protein levels at approximately 12 J. CONCLUSIONS: There appears to be a threshold effect where there is very little increased collagen III mRNA and protein expression until the laser fluence reaches around 12J.

Collagen↗

PubMed2005

Induces vasodilatation of rat mesenteric artery in vitro mainly by inhibiting receptor-mediated Ca(2+)-influx and Ca(2+)-release.

The purpose of this study was to investigate the effect of atropine on peripheral vasodilation and the mechanisms involved. The isometric tension of rat mesenteric artery rings was recorded in vitro on a myograph. The results showed that atropine, at concentrations greater than 1 microM, relaxed the noradrenalin (NA)-precontracted rat mesenteric artery in a concentration-dependent manner. Atropine-induced vasodilatation was mediated, in part, by an endothelium-dependent mechanism, to which endothelium-derived hyperpolarizing factor may contribute. Atropine was able to shift the NA-induced concentration-response curve to the right, in a non-parallel manner, suggesting the mechanism of atropine was not mediated via the (alpha1-adrenoreceptor. The beta-adrenoreceptor and ATP sensitive potassium channel, a voltage dependent calcium channel, were not involved in the vasodilatation. However, atropine inhibited the contraction derived from NA and CaCI2 in Ca(2+)-free medium, in a concentration dependent manner, indicating the vasodilatation was related to the inhibition of extracellular Ca2+ influx through the receptor-operated calcium channels and intracellular Ca2+ release from the Ca2+ store. Atropine had no effect on the caffeine-induced contraction in the artery segments, indicating the inhibition of intracellular Ca2+ release as a result of atropine most likely occurs via the IP3 pathway rather than the ryanodine receptors. Our results suggest that atropine-induced vasodilatation is mainly from artery smooth muscle cells due to inhibition of the receptor-mediated Ca(2+)-influx and Ca(2+)-release, and partly from the endothelium mediated by EDHF.

Adrenergic alpha-Agonists↗