Biomedical subjects

Z Zuo

Publications and source records attributed to Z Zuo.

At least 19 recordsLinked to original sources

PubMed2003

Isoflurane preconditioning reduces purkinje cell death in an in vitro model of rat cerebellar ischemia.

We monitored survival of Purkinje cells in rat cerebellar slices to test the hypothesis that isoflurane preconditioning reduces ischemia-induced neuronal death. Preconditioning the brain slices with isoflurane, a volatile anesthetic commonly used in clinical practice, at 1-4% for 15 min at 37 degrees C significantly decreased Purkinje cell injury and death caused by a 20-min ischemia (simulated by oxygen-glucose deprivation, OGD). The effective concentration for half of the maximal effect (EC(50)) for this isoflurane preconditioning-induced neuroprotection was 1.17+/-0.31% and the maximal protective effects were achieved at 3% or higher concentrations of isoflurane. In addition, preconditioning the cells with isoflurane for 15-30 min was needed for the preconditioning to be maximally protective. Although farnesyl protein transferase inhibitor III blocked the protective effects of OGD preconditioning (a 3-min OGD 15 min before the 20-min OGD), this inhibitor did not affect the neuroprotection induced by isoflurane preconditioning. While DL-threo-beta-hydroxyaspartic acid (THA), a specific glutamate transporter inhibitor, did not change basal OGD-induced cell death rate, THA blocked the neuroprotection induced by isoflurane preconditioning but not by OGD preconditioning. Glybenclamide, a K(ATP) channel inhibitor, did not block the neuroprotection induced by either isoflurane or OGD preconditioning. Our results suggest that isoflurane preconditioning is neuroprotective. The isoflurane concentrations and times needed for the preconditioning to be neuroprotective are clinically relevant. The mechanisms of this protection seem to involve modulation of glutamate transporter activity.

Amino Acid Transport System X-AG↗

PubMed2001

High-performance liquid chromatographic method for simultaneous determination of hawthorn active components in rat plasma.

A simple HPLC method with photodiode-array (PDA) ultraviolet detection was developed for the simultaneous determination of four active polyphenol components of hawthorn (Crataegus), chlorogenic acid, epicatechin, hyperoside and isoquercitrin, in rat plasma. Following extraction from the plasma samples with ethyl acetate-methanol (2:1, v/v), these four compounds were successfully separated using a C18 column with a gradient elution of 5 and 25% acetonitrile in 25 mM phosphate buffer (pH 2.4). The flow-rate was set at 1 ml/min and the eluent was detected at 325 nm for chlorogenic acid, 278 nm for epicatechin, and 360 nm for both hyperoside and isoquercitrin. Narignin (0.82 microg) was used as the internal standard and was detected at 278 nm. The method is linear over the studied range of 0.16-40, 0.63-160, 0.13-32 and 0.13-30 microg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin, respectively. The correlation coefficient for each analyte was greater than 0.995. The intra-day and inter-day precision of the analysis was better than 4 and 7%, respectively. The extraction recoveries at low to high concentration were greater than 85% for both epicatechin and chlorogenic acid, and greater than 94% for both hyperoside and isoquercitrin. The detection limits were 0.04, 0.20, 0.03 and 0.03 microg/ml for chlorogenic acid, epicatechin, hyperoside and isoquercitrin. The developed method was used to analyze the plasma concentrations of the four analytes after the intravenous administration of hawthorn polyphenol extract to rats.

Animals↗

PubMed2001

Isoflurane enhances glutamate uptake via glutamate transporters in rat glial cells.

In this study I examined whether isoflurane, an inhalational anesthetic used commonly in clinical practice, affected glutamate uptake via glutamate transporters, proteins expressed in the plasma membrane of cells in the central nervous system. Isoflurane at clinically relevant concentrations (1-3%) caused a time-, sodium- and concentration-dependent increase of glutamate uptake in primary cultures of rat cerebral mixed glial cells. This enhancement was inhibited by a specific glutamate transporter inhibitor. The study also demonstrated that 2.0% isoflurane significantly increased both Vmax and Km of transporter-mediated glutamate uptake. Thus, isoflurane enhances glutamate uptake by a pathway that requires function of glutamate transporters. This represents a novel pharmacological effect of inhalational anesthetics and may contribute to isoflurane-induced anesthesia and neuroprotective effects.

ATP-Binding Cassette Transporters↗

PubMed2001

Prolongation of allograft survival with viral IL-10 transfection in a highly histoincompatible model of rat heart allograft rejection.

BACKGROUND: The ability to express genes with potential immunoregulatory capacity could reduce the immunogenicity of allografts and result in long-term graft survival. In this study, we examine the feasibility of transferring viral interleukin-10 (vIL-10) gene into rat hearts using adenovirus by intracoronary administration. The subsequent effects of delivered vIL-10 alone or with subtherapeutic doses of cyclosporine A (CsA) on parameters of allograft rejection (AR) were also examined. METHODS: Recombinant adenovirus vectors containing vIL-10 (Ad-vIL-10) or beta-galactosidase (Ad-beta-gal) were derived from adenovirus type 5. vIL-10 expression in supernatants of transfected COS7 cell cultures and in transfected heart allografts were examined by enzyme immunoassay (EIA) and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. Rat heart transplants (LEWS->ACI) were performed in five groups [group 1: no treatment, group 2: Ad-beta-gal, group 3: AdvIL-10, group 4: CsA (10 mg/kg), and group 5: Ad-vIL10+CsA (10 mg/kg)]. Allograft survival was determined by palpating heartbeats. Allograft tissues were also submitted for histological study. RESULTS: vIL-10 expression was shown in both transfected COS7 cells and heart isografts. Animals transfected with vIL-10 showed prolongation of graft survival (19.6 vs. 12 days, P<0.001) when compared to beta-gal transfected controls. Animals treated with a single low dose injection of CsA showed no significant prolongation of graft survival compared to controls (11.7 vs. 10.5 days). Animals treated with both vIL-10 and CsA demonstrated a synergistic prolongation of allograft survival compared with controls and with animals treated with CsA or vIL-10 treatment alone (36.7 days vs. 11.7, P<0.001 or 36.7 vs.19.6, P<0.001, respectively). Histological study showed that allografts from untreated controls exhibited extensive AR with loss of graft architecture by day 7 posttransplant while those from the vIL-10 group showed less AR. The best pathological scores were seen in vIL-10 + CsA-treated animals. CONCLUSIONS: 1) Delivering Ad-vIL-10 into donor hearts by intracoronary perfusion results in overexpression of vIL-10 and significantly prolongs cardiac allograft survival in a highly histoincompatible rat model. 2) Subtherapeutic doses of CsA do not prolong allograft survival, but act synergistically with vIL-10 to significantly prolong graft survival beyond that achieved with either agent alone.

Adenoviridae↗

PubMed2000

An efficient route to the production of an IgG-like bispecific antibody.

Production of IgG-form bispecific antibody (BsAb-IgG) by co-expressing two antibodies in transfected cells is often inefficient owing to the unwanted pairing between the component heavy and light chains. We have developed an efficient method for the production of a novel IgG-like BsAb by using the natural dimerization mechanism between IgG heavy and light chains. Two single-chain Fv (scFv) of different specificity are fused to the constant domain of human kappa chain (C(L)) and the first constant domain of human heavy chain (C(H1)), to form two polypeptides, (scFv)(1)-C(L) and (scFv)(2)-C(H1)-C(H2)-C(H3), respectively. Co-expression of the two polypeptides in mammalian cells results in the formation of a covalently linked IgG-like hetero-tetramer, Bs(scFv)(4)-IgG, with dual specificity. Our approach yields a homogeneous bispecific IgG-like antibody product with each molecule containing four antigen binding sites, two for each of its target antigens. A Bs(scFv)(4)-IgG was prepared using two scFv antibodies each directed against a different epitope of a vascular endothelial growth factor receptor, the kinase insert domain-containing receptor (KDR). The Bs(scFv)(4)-IgG is capable of simultaneously binding to the two epitopes on the receptor. Further, the Bs(scFv)(4)-IgG also retains the antigen-binding efficacy and biological activity of its component antibodies.

Amino Acid Sequence↗

PubMed2000

Interspecies comparison of pharmacokinetics of the novel triazole antifungal agent SYN-2869 and its derivatives.

The pharmacokinetics and distribution in tissue of several novel triazole antifungal agents were studied in different animal species in order to select an appropriate lead compound. The purpose of the study was also to determine species differences in pharmacokinetics for SYN azoles to select the most appropriate species for secondary efficacy and toxicological evaluation of the selected compound. SYN-2836, SYN-2869, SYN-2903, and SYN-2921 were rapidly absorbed into the systemic circulation and reached maximum concentrations (C(max)s) of 7.31 +/- 2.53, 6.29 +/- 0.85, 6.16 +/- 0.39, and 3.41 +/- 0.34 microg/ml, respectively, in BALB/c mice after administration of an oral dose of 50 mg/kg of body weight, with bioavailability being greater than 45% in all mice. The areas under the concentration-time curve from time zero to infinity (AUC(0-infinity)s) after administration of a single intravenous dose of 20 mg/kg to mice varied between 25.0 and 63.6 microg. h/ml. The half-life was in the range of 4.5 to 6 h. In Sprague-Dawley rats there was no significant difference in AUC(0-infinity) after administration of a single intravenous dose of 20 mg/kg, but on oral administration, the bioavailability of SYN-2836 was extremely low, while that of SYN-2869 was only 14.7%. In New Zealand White rabbits the C(max) and the time to reach C(max) for SYN-2836 and SYN-2869 after administration of a single oral dose of 50 mg/kg were similar. There were significant differences in AUC(0-infinity) and half-life between SYN-2836 and SYN-2869. On the other hand, in beagle dogs the C(max) and AUC(0-infinity) of SYN-2836 after administration of a single oral dose of 30 mg/kg were 4.82 +/- 1.54 microg/ml and 41.8 +/- 15.7 microg. h/ml, respectively, which were threefold higher than those of SYN-2869. The concentrations of the SYN compounds in tissue indicated that the AUC(0-infinity)s of SYN-2836, SYN-2869, SYN-2903, and SYN-2921 in mouse lungs were significantly different from each other. The ratios of the concentrations of the SYN azoles in lungs to those in plasma were also significantly different from those for itraconazole. Among the SYN azoles the highest concentration in the lungs was found for SYN-2869. The higher level of distribution of SYN-2869 into lung tissue was considered to contribute to the potent efficacy in respiratory tract infection models compared with the potency of itraconazole. Significant differences in the pharmacokinetics of these compounds were observed in different animal species, and selection of an animal model for further evaluation was based on results obtained from these studies.

Administration, Oral↗

PubMed1999

Ser/Thr protein phosphatase type 5 (PP5) is a negative regulator of glucocorticoid receptor-mediated growth arrest.

Ligand-induced glucocorticoid receptor (GR) activation has recently been linked to the inhibition of cell proliferation via the transcriptional induction of p21(WAF1/Cip1), which functions as a universal inhibitor of cyclin-dependent protein kinases. Herein, we identify a Ser/Thr protein phosphatase (PP5) that promotes cellular proliferation by inhibiting both glucocorticoid and p53-mediated signaling pathways leading to p21(WAF1/Cip1)-mediated growth arrest. The suppression of PP5 expression (1) markedly increases the association of GR with its cognate DNA-binding sequence, (2) induces GR transcriptional activity without the addition of hormone, and (3) increases dexamethasone-mediated induction of GR reporter activity to a level that is approximately 10 times greater than the maximal response obtainable in the presence of PP5. PP5 has no apparent effect on the binding of hormone to the GR, and dexamethasone-mediated growth arrest correlates with an increase in p53 phosphorylation. Comparative studies in p53-wild-type, p53-defective, and p53-deficient cell lines indicate that either (1) p53 participates in GR-mediated induction of p21(WAF1/Cip1), with the hyperphosphorylation of basal p53 induced by glucocorticoids sufficient for the propagation of an antiproliferative response when PP5 expression is inhibited, or (2) PP5 acts where p53-mediated and GR-induced signaling networks converge to regulate the transcriptional induction of p21(WAF1/Cip1). Thus, aberrant PP5 expression may have an additive effect on the development of human cancers by promoting cell proliferation via the inhibition of a GR-induced antiproliferative signaling cascade, and facilitating neoplastic transformation via the inhibition of a growth-arresting p53-mediated response that guards against genomic instability.

Binding Sites↗

PubMed1999

Inhibition of excitatory neurotransmitter-nitric oxide signaling pathway by inhalational anesthetics.

Primary cultures of cerebral neurons of Sprague-Dawley rats increased cyclic GMP production in response to the stimulation of excitatory amino acids, including N-methyl-D-aspartate, quisqualate, kainate and (+/-)-1-aminocylopentane-trans-1,3-dicarboxylic acid. This increased cyclic GMP production was significantly inhibited by halothane or isoflurane at clinically relevant concentrations (0.5-2%). This inhibition was reversible by treatment with L-arginine, the substrate of nitric oxide synthase. However, the increase of cyclic GMP production stimulated by sodium nitroprusside, an activator of soluble guanylate cyclase, was not inhibited by halothane or isoflurane. Neither halothane nor isoflurane affected the basal cyclic GMP production. Activation of the excitatory amino acid neurotransmitter-stimulated nitric oxide-guanylate cyclase signaling pathway increases intracellular cyclic GMP content in neurons. Our results suggest that halothane or isoflurane inhibited this signaling pathway stimulated by selective agonists of each subtype of receptors for excitatory amino acid neurotransmitters. This inhibition may be involved in mechanisms of anesthesia and analgesia. The site(s) of the inhibition is (are) proximal to the activation of neuronal nitric oxide synthase.

Anesthetics, Inhalation↗

PubMed1999

A low voltage-activated Ca2+ current mediates cytokine-induced pancreatic beta-cell death.

Insulin-dependent diabetes mellitus is characterized by the selective destruction of pancreatic beta-cells. Chronic treatment with cytokines induced a low voltage-activated (LVA) Ca2+ current in mouse beta-cells. The concomitant increase in the basal cytoplasmic free Ca2+ concentration ([Ca2+]i) was associated with DNA fragmentation and cell death. Antagonists of LVA Ca2+ channels prevented this elevation of basal [Ca2+]i and DNA fragmentation and reduced the percentage of cell death. Exposure to cytokines did not affect the profile of Ca2+ currents or basal [Ca2+]i in glucagon-secreting alpha-cells. An increased Ca2+ signal through LVA Ca2+ channels may thus be a key feature in cytokine-induced beta-cell destruction.

Animals↗

PubMed1998

Fostriecin-mediated G2-M-phase growth arrest correlates with abnormal centrosome replication, the formation of aberrant mitotic spindles, and the inhibition of serine/threonine protein phosphatase activity.

Fostriecin, a structurally unique phosphate ester, is presently under evaluation in clinical trials to determine its potential use as an antitumor drug in humans. Fostriecin has been reported as having inhibitory activity against DNA topoisomerase type II and protein phosphatases implicated in cell-cycle control. However, the relative contribution of these mechanisms to the antitumor activity of fostriecin has not yet been elucidated. In this study, after confirming that fostriecin is a potent inhibitor of serine/threonine protein phosphatase type 2A and a weak inhibitor of serine/threonine protein phosphatase type 1, we show that fostriecin inhibits approximately 50% of the divalent cation independent serine/threonine protein phosphatase (PPase) activity contained in whole cell homogenates of Chinese hamster ovary cells at concentrations associated with antitumor activity (1-20 microM). Investigations into the cellular effects produced by fostriecin treatment reveal that 1-20 microM fostriecin induces a dose-dependent arrest of cell growth during the G2-M phase of the cell cycle. Immunostaining of treated cells indicates that growth arrest occurs before the completion of mitosis and that fostriecin-induced growth arrest is associated with the aberrant amplification of centrosomes, which results in the formation of abnormal mitotic spindles. The "mitotic block" induced by fostriecin is reversible if treatment is discontinued in <24 h. However, after approximately 24-30 h of continuous treatment, growth arrest is not reversible, and treated cells die even when placed in fostriecin-free media. Correlative studies conducted with established PPase inhibitors reveal that, when applied at concentrations that inhibit PPase activity to a comparable extent, both okadaic acid and cantharidin also induce aberrant centrosome replication, the appearance of multiple aberrant mitotic spindles, and G2-M-phase growth arrest. These studies add additional support to the concept that PPase inhibition underlies the antitumor activity of fostriecin and suggest that other type-selective PPase inhibitors should be evaluated for potential antitumor activity.

Alkenes↗

PubMed1998

Serine/threonine protein phosphatase type 5 acts upstream of p53 to regulate the induction of p21(WAF1/Cip1) and mediate growth arrest.

Understanding how alterations in growth control pathways are translated into changes in the cell cycle regulatory machinery is a major challenge for understanding the development of human cancers. The ability of both tumor suppressor proteins, p53 and BRCA1, to induce the expression of p21(WAF1/Cip1) in combination with the inhibitory activity of p21(WAF1/Cip1) against cyclin-dependent kinases suggests that the regulation of p21(WAF1/Cip1) expression is an important aspect of mammalian cell cycle growth control. To elucidate the role of serine/threonine protein phosphatase type 5 (PP5) in processes regulating cell cycle progression, we developed antisense oligodeoxynucleotides targeted against PP5 (e.g. ISIS 15534) that specifically inhibit PP5 gene expression. Employing ISIS 15534, we demonstrate that the specific inhibition of PP5 gene expression has a marked antiproliferative effect on cells, characterized by induction of p21(WAF1/Cip1) and the subsequent arrest of cell growth. Investigations into the mechanisms leading to growth arrest reveal that, in the absence of PP5, the expression of p21(WAF1/Cip1) is induced in p53-competent A549 cells but not in p53 protein-deficient T-24 cells. Employing a stable cell line derived from p53-deficient human fibroblast that contains tetracycline-regulated transactivator and operator plasmids to control the expression of wild-type p53 (TR9-7 cells), we then show that the induction of p21(WAF1/Cip1), which occurs in response to the inhibition of PP5 expression, requires the p53 protein. Additional studies indicate that PP5 acts upstream of p53, influencing both the phosphorylation state and the ability of p53 to bind DNA, without causing an increase in p53 gene transcription. Together these studies suggest that PP5 is a regulatory component of a signaling pathway that affords replicating cells G1 checkpoint growth control and that it is the regulation of PP5 that, in turn, controls p53-mediated expression of p21(WAF1/Cip1) and growth arrest in this pathway. In addition, since the inhibition of PP5 gene expression has marked antiproliferative activity and the overexpression of p21(WAF1/Cip1) blocks the growth of tumor cells, these studies suggest that compounds that inhibit of PP5 gene expression may be useful in the treatment of human cancers.

Cell Division↗

PubMed1998

Purification and cDNA cloning of maize Poly(ADP)-ribose polymerase.

Poly(ADP)-ribose polymerase (PADPRP) has been purified to apparent homogeneity from suspension cultures of the maize (Zea mays) callus line. The purified enzyme is a single polypeptide of approximately 115 kD, which appears to dimerize through an S-S linkage. The catalytic properties of the maize enzyme are very similar to those of its animal counterpart. The amino acid sequences of three tryptic peptides were obtained by microsequencing. Antibodies raised against peptides from maize PADPRP cross-reacted specifically with the maize enzyme but not with the enzyme from human cells, and vice versa. We have also characterized a 3.45-kb expressed-sequence-tag clone that contains a full-length cDNA for maize PADPRP. An open reading frame of 2943 bp within this clone encodes a protein of 980 amino acids. The deduced amino acid sequence of the maize PADPRP shows 40% to 42% identity and about 50% similarity to the known vertebrate PADPRP sequences. All important features of the modular structure of the PADPRP molecule, such as two zinc fingers, a putative nuclear localization signal, the automodification domain, and the NAD+-binding domain, are conserved in the maize enzyme. Northern-blot analysis indicated that the cDNA probe hybridizes to a message of about 4 kb.

Amino Acid Sequence↗

PubMed1998

[Spinal segment distribution of neural innervation related to houhai acupoint and compared with zusanli and dazhui acupoints in domestic chicken].

OBJECTIVE: The aim of this study was to demonstrate the spinal segmental innervation of Houhai, Dazhui and Zusanli acupoints in domestic chicken. METHODS: The horseradish peroxidase conjugated cholera toxin B subunit (CB-HRP) was injected into the regions of the three acupoints namely, Houhai Dazhui and Zusanli respectively in separate groups of chicken. The frozen sections of spinal cord and dorsal ganglia were prepare for labelling using TMB as a chromogen. RESULTS: (1) In Houhai group the anterograde transganlionic labelling terminals were densely distributed in the dorsal horn and dorsal commissure nucleus. The moto-neurons in ventral horn labelled retrogradely appeared fine arborization of dendrites. There were labelled cell bodies in the dorsal region of the ventral horn (lamina VII) or dorsal commissure nucleus. (2) In Dazhui group, the bundles of labelled fibers presented from laminea I and II to IX in the caudal cervical enlargements and two upper thoracic segments. The labelled motoneurons were shown in medial and lateral groups. The most numourous of labelled ganglionic cells appeared in this group. (3) The labelling sensory ganglionic neurons and their terminals in spinal cord related Zusanli acupoint were overlaped with those related Houhai acupoint. The largest numbers of the labelled ventral motoneurons occured in the Zusanli group. CONCLUSIONS: The results demontrated the patterns of segmental innervation corresponding respectively to Houhai, Dazhui, and Zusanli acupoints. The anterograde afferent labelling terminals and interrelationship of the dendritic arborization of retrograde labelling motoneurons (somatic or visceral) provided neuroanatomical evidences for the innervation of the acupoints.

Acupuncture Points↗

PubMed1997

Population-based study of glutathione S-transferase mu gene deletion in adult glioma cases and controls.

Gene deletion at the glutathione S-transferase mu locus (GSTM1) has previously been associated with increased risk for environmentally-induced cancers (e.g. smoking-related lung cancer). In the present study we examined the hypothesis that GSTM1 deletion is a risk factor for malignant brain tumors in adults. We compared the prevalence of the GSTM1 homozygous deletion polymorphism in 158 Caucasian adults with gliomas with 157 controls. Cases and controls were drawn from a large population-based case-control study of brain cancers in six San Francisco Bay area counties. Overall, the prevalence of the GSTM1 deletion was similar in cases (83/158; 53%) and controls (78/157; 50%). Among brain tumor cases, analysis of variance modeling indicated a significant interaction of GSTM1 genotype and gender associated with age at diagnosis (P = 0.02). This effect was due to the fact that women with GSTM1 deletion were younger on average at diagnosis than women who were GSTM1 positive (43.9 years versus 52.4 years, respectively). Age at diagnosis among men was similar for those who were GSTM1 deleted and GSTM1 positive (49.4 years and 47.2 years, respectively). The younger age at diagnosis of GSTM1 null female cases compared with GSTM1 positive cases was observed in astrocytoma as well as the higher grade tumors (e.g. glioblastoma multiforme). There was no association of GSTM1 deletion with age or gender in controls. These studies suggest that among female cases, GSTM1 deletion may be associated with earlier age at onset. Confirmation of these findings could provide important clues to gene-environment interactions in the etiology of malignant brain tumors.

Adult↗

PubMed1997

Inhalational anesthetics up-regulate constitutive and lipopolysaccharide-induced inducible nitric oxide synthase expression and activity.

Nitric oxide (NO) is an important biological messenger involved in the regulation of blood vessel tone, neurotransmission, inflammatory responses, and host defenses. Inhalational anesthetics have been shown to inhibit the function of the NO signaling pathway in a variety of tissues. In addition, acute inhibition of the NO signaling pathway significantly reduced the required alveolar concentration of halothane or isoflurane for anesthesia, which suggests a role for the NO signaling pathway in mechanisms of anesthesia and consciousness. We now report that inhalational anesthetics affect gene expression of nitric oxide synthases (NOS) (EC 1.14.13.39), the enzymes that synthesize NO from L-arginine. Both halothane and isoflurane, at clinically relevant concentrations, significantly up-regulate the mRNA, protein, and activity level of NOS in lipopolysaccharide-treated macrophages (inducible NOS; type II NOS), and bovine pulmonary endothelial cells (endothelial constitutive NOS; type III NOS). This is a novel interaction between inhalational anesthetics and the NO signaling pathway and has wide-ranging implications for both clinical medicine and experimental biology.

Anesthetics, Inhalation↗

PubMed1997

[Spinal segment distribution of neural innervation related houhai acupoint--studied by CB-HRP tracing method focused on observation of the dendrites of spinal motor neurons].

The spinal segment distribution of neural innervation related Houhai acupoint in rats has been investigted by using horseradish peroxidase conjugated cholera toxin B subunit (CB-HRP) tracing technique. Spinal motoneurons (Mn) in L6-S1 were labeled retrogradely by CB-HRP, and their features have been characterized: 1) their marginal plexus of the dendrites radially projected to the lateral and/or anterior funiculus and their distal portions forming subpial dendritic plexus; 2) the medial dendrites ran along the ventral margin of the gray commissure and their distal portions surrounded the central canal' forming a subependymal dendritic plexus. Both of them are Golgi-phobic. Some distal branches of dendrites penetrated to the contralateral gray matter. The dendritic arbors of the labeled motoneurons in the group of electro-acupuncture or group of acupoint-inoculation with sheep red blood cells contracted in comparison with that in the normal control group. The primary sensory transganglionic labeled fibers and preterminal fibers revealed by CB-HRP in the dorsal horn and dorsal commissural nucleus of the spinal cord (L5-S2) converged and overlaped with the dendrites of retrogradely labeled motoneurons. The results indicated there is a reflect circuit of afferent-integration-efferent neuro-network in the spinal cord related Houhai acupoint. The Mns retrogradely labeled by CB-HRP in the L6-S1 segments might be involved in Houhai acupuncture.

Acupuncture Points↗

PubMed1996

Halothane and isoflurane dose-dependently inhibit the cyclic GMP increase caused by N-methyl-D-aspartate in rat cerebellum: novel localization and quantitation by in vitro autoradiography.

Using a novel technique combining immunohistochemistry and in vitro quantitative autoradiography, we were able simultaneously to localize and quantitate cyclic guanosine 3',5'-monophosphate (cGMP)-immunoreactive binding in adult rat cerebellum. The cGMP-immunoreactive binding was predominantly detected in the molecular layer of the cerebellum under both basal and N-methyl-D-aspartate-stimulated conditions. N-Methyl-D-aspartate significantly increased the cGMP binding density in the molecular layer. This increased cGMP level was dose-dependently and significantly inhibited by the inhalational anesthetics halothane and isoflurane. This increased cGMP level was also significantly inhibited by L-NG-nitroarginine methyl ester, an inhibitor of nitric oxide synthases. L-Arginine, the substrate of nitric oxide synthase, reversed the inhibition by L-NG-nitroarginine methyl ester on the cGMP increase. This novel combination of immunohistochemistry and quantitative autoradiography may be used to localize and quantitate simultaneously cGMP or other substances in animal tissues. Our data also confirm that nitric oxide is involved in the stimulation of cGMP formation by N-methyl-D-aspartate. Halothane and isoflurane inhibit the nitric oxide-guanylyl cyclase signaling pathway activated by the excitatory amino acid N-methyl-D-aspartate in the brain, which may be a component of the mechanisms by which these two inhalational anesthetics produce their anesthetic effects.

Anesthetics, General↗

PubMed1996

Halothane and isoflurane inhibit vasodilation due to constitutive but not inducible nitric oxide synthase. Implications for the site of anesthetic inhibition of the nitric oxide/guanylyl cyclase signaling pathway.

BACKGROUND: Inhalational anesthetics inhibit the nitric oxide-guanylyl cyclase signaling pathway, but the site of this inhibition is not yet clear. This study was designed to test the hypothesis that receptor activation or downstream signaling events leading to nitric oxide synthase activation are important sites for this inhibition by comparing the effect of anesthetics on vasodilation caused by the calcium-dependent constitutive endothelial nitric oxide synthase versus the calcium-independent inducible nitric oxide synthase. METHODS: Endothelium-intact or -denuded rat thoracic aorta rings preincubated with or without lipopolysaccharide were mounted for isometric tension measurement, constricted with phenylephrine, then relaxed with methacholine in the presence or absence of halothane (1-3%) or isoflurane (1-3%). The cyclic guanosine 3,5-monophosphate content in the endothelium-denuded rings preincubated with or without lipopolysaccharide in the presence or absence of 3% halothane or 3% isoflurane was quantified by radioimmunoassay. The activity of partially purified inducible nitric oxide synthase from activated mouse macrophage was assayed in the presence or absence of halothane (1-4%) or isoflurane (1-5%) by the conversion of 3H-L-arginine to 3H-L-citrulline. RESULTS: Halothane and isoflurane inhibited methacholine-stimulated, nitric oxide-mediated vasorelaxation in endothelium-intact aortic rings. Neither halothane nor isoflurane affected the vasorelaxation caused by basal endothelial nitric oxide synthase or inducible nitric oxide synthase activity. Neither anesthetic altered the cyclic guanosine 3,5-monophosphate increase caused by inducible nitric oxide synthase in the lipopolysaccharide-treated rings. CONCLUSIONS: The results demonstrated that halothane and isoflurane inhibit only receptor/calcium-activated nitric oxide synthase action and that direct inhibition of nitric oxide synthase, soluble guanylyl cyclase, or an interaction with nitric oxide are not responsible for anesthetic inhibition of endothelium-dependent vasorelaxation.

Anesthetics, Inhalation↗