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3.
RSC Adv ; 12(24): 15167-15179, 2022 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-35693236

RESUMO

This study explored the structural, electrical, and magnetic properties of diamagnetic aluminium (Al3+) substituted nickel-zinc-cobalt (Ni-Zn-Co) mixed spinel ferrites, though the research on this area is in the infancy stage. Single-phase cubic spinel structures with the Fd3̄m space group of the synthesized Ni0.4Zn0.35Co0.25Fe(2-x)Al x O4 (0 ≤ x ≤ 0.12) ferrite samples were confirmed by X-ray diffraction (XRD) analysis. The average particle size ranged from 0.67 to 0.39 µm. Selected area electron diffraction (SAED) patterns were indexed according to the space group Fd3m, representing the particle's crystallinity. The optical band gaps ranged from 4.784 eV to 4.766 eV. Frequency-dependent dielectric constants and ac conductivity measurement suggested that the prepared ferrites were highly resistive. Relaxation times were reduced to a low value from 45.45 µs to 1.54 µs with the composition x. The Curie temperatures (T c) were 615-623 K for all samples. Real part permeabilities (µ /) were relatively stable up to an extended frequency range of 106 Hz with relative quality factors (RQF) of around 103. Tuning of the properties indicates that the fabricated ferrites may be promising for high-frequency electronic devices.

4.
RSC Adv ; 12(8): 4656-4671, 2022 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-35425488

RESUMO

This study presents a modification of structure-dependent elastic, thermodynamic, magnetic, transport and magneto-dielectric properties of a Ni-Zn-Co ferrite tailored by Gd3+ substitution at the B-site replacing Fe3+ ions. The synthesized composition of Ni0.7Zn0.2Co0.1Fe2-x Gd x O4 (0 ≤ x ≤ 0.12) crystallized with a single-phase cubic spinel structure that belongs to the Fd3̄m space group. The average particle size decreases due to Gd3+ substitution at Fe3+. Raman and IR spectroscopy studies illustrate phase purity, lattice dynamics with cation disorders and thermodynamic conditions inside the studied samples at room temperature (RT = 300 K). Ferromagnetic to paramagnetic phase transition was observed in all samples where Curie temperature (T C) decreases from 731 to 711 K for Gd3+ substitution in Ni-Zn-Co ferrite. In addition, Gd3+ substitution reinforces to decrease the A-B exchange interaction. Temperature-dependent DC electrical resistivity (ρ DC) and temperature coefficient of resistance (TCR) have been surveyed with the variation of the grain size. The frequency-dependent dielectric properties and electric modulus at RT for all samples were observed from 20 Hz to 100 MHz and the conduction relaxation processes were found to spread over an extensive range of frequencies with the increase in the amount of Gd3+ in the Ni-Zn-Co ferrite. The RLC behavior separates the zone of frequencies ranging from resistive to capacitive regions in all the studied samples. Finally, the matching impedance (Z/η 0) for all samples was evaluated over an extensive range of frequencies for the possible miniaturizing application.

5.
Int J Oral Maxillofac Surg ; 49(7): 940-944, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31926823

RESUMO

Temporomandibular joint (TMJ) reconstruction is traditionally invasive. Several investigators have developed animal models, including mouse models, to study the TMJ. However, there are no detailed descriptions of a mouse model to be followed for additional research. The goal of this project was to study minimally invasive TMJ regeneration using tissue engineering in mice. As part of the project, a detailed mouse model was developed, which is described in this article. Eight carcasses were used to study the anatomy of the TMJ of the mouse and 36 mice were used to describe the surgical approach and perioperative management. The study showed similarities and differences when compared to humans. One mouse died suddenly 10 days postoperatively, while 35 mice survived the operation. Keratitis and wound dehiscence were the most common complications. Investigators reviewing this paper should be able to use this mouse model to further study TMJ regeneration in mice.


Assuntos
Prótese Articular , Transtornos da Articulação Temporomandibular , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Regeneração , Articulação Temporomandibular
6.
BMC Complement Altern Med ; 17(1): 181, 2017 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-28359331

RESUMO

BACKGROUND: This study was aimed to evaluate antioxidant and α-glucosidase inhibitory activity, with a subsequent analysis of total phenolic and total flavonoid content of methanol extract and its derived fractions from Clinacanthus nutans accompanied by comprehensive phytochemical profiling. METHODS: Liquid-liquid partition chromatography was used to separate methanolic extract to get hexane, ethyl acetate, butanol and residual aqueous fractions. The total antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazy (DPPH) radical scavenging and ferric reducing antioxidant power assay (FRAP). The antidiabetic activity of methanol extract and its consequent fractions were examined by α-glucosidase inhibitory bioassay. The chemical profiling was carried out by gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC Q-TOF MS). RESULTS: The total yield for methanol extraction was (12.63 ± 0.98) % (w/w) and highest fractionated value found for residual aqueous (52.25 ± 1.01) % (w/w) as compared to the other fractions. Significant DPPH free radical scavenging activity was found for methanolic extract (63.07 ± 0.11) % and (79.98 ± 0.31) % for ethyl acetate fraction among all the fractions evaluated. Methanol extract was the most prominent in case of FRAP (141.89 ± 0.87 µg AAE/g) whereas most effective reducing power observed in ethyl acetate fraction (133.6 ± 0.2987 µg AAE/g). The results also indicated a substantial α-glucosidase inhibitory activity for butanol fraction (72.16 ± 1.0) % and ethyl acetate fraction (70.76 ± 0.49) %. The statistical analysis revealed that total phenolic and total flavonoid content of the samples had the significant (p < 0.05) impact on DPPH free radical scavenging and α-glucosidase inhibitory activity. CONCLUSION: Current results proposed the therapeutic potential of Clinacanthus nutans, especially ethyl acetate and butanol fraction as chemotherapeutic agent against oxidative related cellular damages and control the postprandial hyperglycemia. The phytochemical investigation showed the existence of active constituents in Clinacanthus nutans extract and fractions.


Assuntos
Acanthaceae/química , Antioxidantes/química , Inibidores de Glicosídeo Hidrolases/química , Extratos Vegetais/química , Antioxidantes/isolamento & purificação , Antioxidantes/metabolismo , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Inibidores de Glicosídeo Hidrolases/metabolismo , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/metabolismo , Caules de Planta/química , alfa-Glucosidases/química , alfa-Glucosidases/metabolismo
7.
Biol Res ; 49: 24, 2016 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-27090643

RESUMO

This study was undertaken to determine the effects of varied salinity regimes on the morphological traits (plant height, number of leaves, number of flowers, fresh and dry weight) and major mineral composition of 13 selected purslane accessions. Most of the morphological traits measured were reduced at varied salinity levels (0.0, 8, 16, 24 and 32 dS m(-1)), but plant height was found to increase in Ac1 at 16 dS m(-1) salinity, and Ac13 was the most affected accession. The highest reductions in the number of leaves and number of flowers were recorded in Ac13 at 32 dS m(-1) salinity compared to the control. The highest fresh and dry weight reductions were noted in Ac8 and Ac6, respectively, at 32 dS m(-1) salinity, whereas the highest increase in both fresh and dry weight was recorded in Ac9 at 24 dS m(-1) salinity compared to the control. In contrast, at lower salinity levels, all of the measured mineral levels were found to increase and later decrease with increasing salinity, but the performance of different accessions was different depending on the salinity level. A dendrogram was also constructed by UPGMA based on the morphological traits and mineral compositions, in which the 13 accessions were grouped into 5 clusters, indicating greater diversity among them. A three-dimensional principal component analysis also confirmed the output of grouping from cluster analysis.


Assuntos
Minerais/análise , Portulaca/anatomia & histologia , Portulaca/química , Salinidade , Cálcio/análise , Flores/anatomia & histologia , Ferro/análise , Magnésio/análise , Fósforo/análise , Folhas de Planta/anatomia & histologia , Potássio/análise , Valores de Referência , Tolerância ao Sal , Sódio/análise , Zinco/análise
8.
Biol. Res ; 49: 1-19, 2016. ilus, graf, tab
Artigo em Inglês | LILACS | ID: biblio-950851

RESUMO

This study was undertaken to determine the effects of varied salinity regimes on the morphological traits (plant height, number of leaves, number of flowers, fresh and dry weight) and major mineral composition of 13 selected purslane accessions. Most of the morphological traits measured were reduced at varied salinity levels (0.0, 8, 16, 24 and 32 dS m-1), but plant height was found to increase in Ac1 at 16 dS m-1 salinity, and Ac13 was the most affected accession. The highest reductions in the number of leaves and number of flowers were recorded in Ac13 at 32 dS m-1 salinity compared to the control. The highest fresh and dry weight reductions were noted in Ac8 and Ac6, respectively, at 32 dS m-1 salinity, whereas the highest increase in both fresh and dry weight was recorded in Ac9 at 24 dS m-1 salinity compared to the control. In contrast, at lower salinity levels, all of the measured mineral levels were found to increase and later decrease with increasing salinity, but the performance of different accessions was different depending on the salinity level. A dendrogram was also constructed by UPGMA based on the morphological traits and mineral compositions, in which the 13 accessions were grouped into 5 clusters, indicating greater diversity among them. A three-dimensional principal component analysis also confirmed the output of grouping from cluster analysis.


Assuntos
Portulaca/anatomia & histologia , Portulaca/química , Salinidade , Minerais/análise , Fósforo/análise , Potássio/análise , Valores de Referência , Sódio/análise , Zinco/análise , Cálcio/análise , Folhas de Planta/anatomia & histologia , Flores/anatomia & histologia , Tolerância ao Sal , Ferro/análise , Magnésio/análise
9.
J Environ Biol ; 36(6): 1311-7, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26688966

RESUMO

The pot experiment was conducted to select appropriate integrated weed management method in rice under different salinity levels (0, 4 and 8 dS m(-1)). All the parameters including rice and weed measured were significantly influenced by weed control treatments at all salinity levels. Treatments including weed-free condition, Pretilachlor @0.375 kg ai ha(-1) + hand weeding, Propanil + Thiobencarb @ 0.9 kg ai ha(-1) and 1.8 kg ai ha(-1)+ hand weeding performed better under all salinity levels. Pretilachlor @ 0.375 kg ai ha(-1) with one round of hand weeding and propanil + thiobencarb 0.9 kg ai ha(-1) + 1.8 kg ai ha(-1) with one round of hand weeding were comparable to weed-free yields, and were superior to other treatments under salinity condition. Considering all the parameters, pretilachlor @ 0.375 kg ai ha(-1) + one round of hand weeding (at 65 DAT), propanil + thiobencarb 0.9 kg ai ha(-1) +1.8 kg ai ha(-1) + one round of hand weeding (at 65 DAT) gave the most effective control of weeds in rice under saline environments.


Assuntos
Acetanilidas/farmacologia , Herbicidas/farmacologia , Oryza/fisiologia , Plantas Daninhas/efeitos dos fármacos , Salinidade , Água/química , Meio Ambiente
10.
J Environ Biol ; 35(5): 855-64, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25204059

RESUMO

Six weed species (Leptochola chinensis, Echinochloa crus-galli, Echinochloa colona, Jussiaea linifolia, Oryza sativa (weedy rice) and Cyperus iria) were tested for their salt tolerant traits in terms of chlorophyll, proline and mineral nutrients accumulation against different salinity levels (0, 4, 8, 16, 24, 32, and 40 dS m(-1)). Chlorophyll a, b and total chlorophyll content, proline and mineral nutrients accumulation were determined. Salt stress showed prominent effect on all the parameters investigated and there were significant variations between the all weed species. Chlorophyll content, K+, Ca(2+) and Mg(2+) ions in both shoots and roots significantly decreased; while proline and Na+ accumulation significantly increased with increasing salinity up to 40 dS m(-1). In terms of overall performance, Cyperus iria and E. crus-galliwere relatively more tolerant; E. colona and J. linifolia were tolerant; L. chinensis and O. sativa L were salt sensitive, respectively.


Assuntos
Clorofila/metabolismo , Oryza/metabolismo , Plantas Daninhas/metabolismo , Prolina/metabolismo , Salinidade , Cálcio/metabolismo , Magnésio/metabolismo , Malásia , Potássio/metabolismo , Sódio/metabolismo , Estresse Fisiológico
11.
J Environ Biol ; 35(4): 765-79, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25004765

RESUMO

Agriculture, rapid urbanization and geochemical processes have direct or indirect effects on the chemical composition of groundwater and aquifer geochemistry. Hydro-chemical investigations, which are significant for assessment of water quality, were carried out to study the sources of dissolved ions in groundwater of Dinajpur district, northern Bangladesh. The groundwater samplish were analyzed for physico-chemical properties like pH, electrical conductance, hardness, alkalinity, total dissolved solids and Ca2+, Mg2+, Na+, K+, CO3(2-), HCO3(-), SO4(2-) and Cl- ions, respectively. Based on the analyses, certain parameters like sodium adsorption ratio, soluble sodium percentage, potential salinity, residual sodium carbonate, Kelly's ratio, permeability index and Gibbs ratio were also calculated. The results showed that the groundwater of study area was fresh, slightly acidic (pH 5.3-6.4) and low in TDS (35-275 mg I(-1)). Ground water of the study area was found suitable for irrigation, drinking and domestic purposes, since most of the parameters analyzed were within the WHO recommended values for drinking water. High concentration of NO3- and Cl- was reported in areas with extensive agriculture and rapid urbanization. Ion-exchange, weathering, oxidation and dissolution of minerals were major geochemical processes governing the groundwater evolution in study area. Gibb's diagram showed that all the samples fell in the rock dominance field. Based on evaluation, it is clear that groundwater quality of the study area was suitable for both domestic and irrigation purposes.


Assuntos
Água Subterrânea/análise , Poluentes Químicos da Água/análise , Qualidade da Água , Bangladesh , Condutividade Elétrica , Monitoramento Ambiental , Modelos Teóricos , Espectrofotometria Atômica
12.
Biomed Res Int ; 2014: 208584, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24579076

RESUMO

Five Malaysian rice (Oryza sativa L.) varieties, MR33, MR52, MR211, MR219, and MR232, were tested in pot culture under different salinity regimes for biochemical response, physiological activity, and grain yield. Three different levels of salt stresses, namely, 4, 8, and 12 dS m(-1), were used in a randomized complete block design with four replications under glass house conditions. The results revealed that the chlorophyll content, proline, sugar content, soluble protein, free amino acid, and yield per plant of all the genotypes were influenced by different salinity levels. The chlorophyll content was observed to decrease with salinity level but the proline increased with salinity levels in all varieties. Reducing sugar and total sugar increased up to 8 dS m(-1) and decreased up to 12 dS m(-1). Nonreducing sugar decreased with increasing the salinity levels in all varieties. Soluble protein and free amino acid also decreased with increasing salinity levels. Cortical cells of MR211 and MR232 did not show cell collapse up to 8 dS m(-1) salinity levels compared to susceptible checks (IR20 and BRRI dhan29). Therefore, considering all parameters, MR211 and MR232 showed better salinity tolerance among the tested varieties. Both cluster and principal component analyses depict the similar results.


Assuntos
Oryza/anatomia & histologia , Oryza/crescimento & desenvolvimento , Salinidade , Aminoácidos/metabolismo , Carboidratos/análise , Clorofila/metabolismo , Clorofila A , Análise por Conglomerados , Oryza/metabolismo , Filogenia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Raízes de Plantas/ultraestrutura , Análise de Componente Principal , Prolina/metabolismo , Sementes/crescimento & desenvolvimento , Solubilidade
13.
J Environ Biol ; 35(2): 317-26, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24665756

RESUMO

Selection of salt tolerant rice varieties has a huge impact on global food supply chain. Five Malaysian rice (Oryza sativa L.) varieties, MR33, MR52, MR211, MR219 and MR232 were tested in pot experiment under different salinity levels for their response in term of vegetative growth, physiological activities, development of yield components and grain yield. Rice varieties, BRRI dhan29 and IR20 were used as a salt-sensitive control and Pokkali was used as a salt-tolerant control. Three different salinity levels viz. 4, 8, and 12 dS m(-1) were used in a randomized complete block design with four replications under glass house conditions. Two Malaysia varieties, MR211 and MR232 performed better in terms of vegetative growth (plant height, leaf area plant(-1), number of tillers plant(-1), dry matter accumulation plant(-1)), photosynthetic rate, transpiration rate, yield components, grain yield and injury symptoms. While, MR33, MR52 and MR219 verities were able to withstand salinity stress over salt-sensitive control, BRRI dhan29 and IR20.


Assuntos
Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Cloreto de Sódio/farmacologia , Adaptação Fisiológica , Oryza/classificação , Oryza/genética , Folhas de Planta/crescimento & desenvolvimento , Transpiração Vegetal , Salinidade , Tolerância ao Sal/fisiologia , Água/química
14.
J Environ Biol ; 34(5): 847-56, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24558797

RESUMO

A survey was conducted at 100 different rice fields in coastal areas of West Malaysia to identify most common and prevalent weeds associated with rice. Fields surveyed were done according to the quantitative survey method by using 0.5m x 0.5m size quadrate with 20 samples from each field. A total of 53 different weed species belong to 18 families were identified of which 32 annual and 21 perennial; 12 grassy, 13 sedges and 28 broadleaved weeds. Based on relative abundance the most prevalent and abundant weed species were selected in the coastal rice field. Among the 10 most abundant weed species, there were four grasses viz. Echinochloa crusgalli, Leptochloo chinensis, Echinochloo colona, Oryza sotivo L. (weedy rice).; four sedges viz. Fimbristylis miliacea, Cyperus iria, Cyperus difformis, Scirpus grossus and two broadleaved weeds viz. Sphenocleo zeylonica, Jussiaea linifolio. Leptochloa chinensis, E. crusgalli, F. miliocea, E. colona were more prevalent and abundant species out of the 10 most dominant weed species in the coastal rice field of Peninsular Malaysia.


Assuntos
Agricultura , Biota , Oryza/crescimento & desenvolvimento , Plantas Daninhas/fisiologia , Malásia , Plantas Daninhas/classificação , Plantas Daninhas/crescimento & desenvolvimento , Densidade Demográfica
15.
J Environ Biol ; 32(5): 529-36, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22319865

RESUMO

An investigation was made to see the salt tolerance of 10 weed species of rice. Properly dried and treated seeds of weed species were placed on 9 cm diameter petridishes lined with Whatman No. 1 filter paper under 6 salinity regimes, viz. 0 (control), 4, 8, 16, 24 and 32 dS m(-1). The petri dishes were then kept in germinator at 25 +/- 1.0 degrees C and 12 hr light. The number of germinated seeds were recorded daily. The final germination percentage, germination index (GI), seedling vigour index, mean germination time and time for 50% germination were estimated. Root and shoot lengths of the weed seedlings were measured at 20 days after salt application and relative growth values were calculated. Results revealed that salinity decreased final germination percentage, seed of germination as measured by GI, and shoot and root length in all the species. Germination of most of the weed seeds was completely arrested (0) at 32 dS m(-1) salinity except in E. colona (12%) and C. iria (13.9%). The species C. iria, E. colona, J. linifolia and E. crusgalli showed better germination (above 30%) upto 24 dS m(-1) salinity level and were regarded as salt-tolerant weed species. J. linifolia, F. miliacea, L. chinensis and O. sativa L. (weedy rice) were graded as moderately tolerant and S. zeylanica, S. grosus and C. difformis were regarded as least tolerant weed species.


Assuntos
Germinação/efeitos dos fármacos , Oryza/fisiologia , Plantas Daninhas/efeitos dos fármacos , Sementes/efeitos dos fármacos , Cloreto de Sódio/toxicidade , Adaptação Fisiológica , Agricultura , Germinação/fisiologia , Plantas Daninhas/classificação , Plantas Daninhas/fisiologia , Sementes/classificação , Sementes/fisiologia , Cloreto de Sódio/química , Especificidade da Espécie , Estresse Fisiológico , Água/química
16.
J Environ Biol ; 32(6): 821-9, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22471222

RESUMO

Plant stature of a rice crop is an important selection criterion. As plant height is a quantitative trait it is influenced by environmental conditions. A field experiment was conducted with 40 rice genotypes to assess the fluctuation and stability of plant height in a series of 16 environmental situations. The effects of genotype (G), environment (E) and all the components of GxE interaction were highly significant. Among the genotypes, Jamai sohagi was extremely sensitive (bi = 1.37) to environmental changes, and indicating lowest adaptability over the environments. Plant height of seven genotypes viz. Basmati PNR346, Benaful, BRRIdhan28, BRRIdhan38, BRRIdhan39, Gandho kasturi and Neimat, having the bi values between 0.59 and 0.72, showed high stability against environmental changes. The otherseven genotypes viz. Badshabhog, Basmati Tapl-90, Kamini soru, Khazar, Laljira, Sarwati and Ukni madhu expressed only nonlinear sensitivity (S2di = 90-181)) and thus unpredictable fluctuation. Twenty one genotypes indicated their average stability (bi = 0.91-1.15) over the environments.


Assuntos
Genótipo , Oryza/crescimento & desenvolvimento , Oryza/genética , Bangladesh , Meio Ambiente , Característica Quantitativa Herdável
17.
J Egypt Public Health Assoc ; 71(5-6): 439-63, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-17214190

RESUMO

A case control study was conducted in Kafr El-Sheikh Governorate, Egypt, a rural community, to assess the relation of parasites and diarrhoea among children <5 years. A sample of 196 cases with diarrhoea and 83 non-diarrhoeic controls were included in the study. A questionnaire was completed for every child and weight and height were recorded. A stool sample was obtained and examined for parasites present. The results revealed that 70.3% of cases had parasites compared to 59% of controls. The most common parasites found were Entamoeba histolytica, cryptosporidium, and Giardia lamblia consecutively. In both groups the percent positive parasitic infection increased with age. The different socioeconomic and sanitary indicators studied were similar among both groups and could not explain the diarrhoea present except for the significantly higher presence of piped water inside houses of controls. Study of malnutrition revealed that a significantly higher percentage were stunted (15.6%) among cases than among controls (6.5%) and 13.8% were wasted among cases compared to only 2% among controls. Undernourished cases were 14.8% compared to 4.3% of controls.


Assuntos
Diarreia/epidemiologia , Diarreia/parasitologia , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Saúde da População Rural/estatística & dados numéricos , Distribuição por Idade , Estudos de Casos e Controles , Transtornos da Nutrição Infantil/epidemiologia , Transtornos da Nutrição Infantil/parasitologia , Pré-Escolar , Diarreia/complicações , Escolaridade , Egito/epidemiologia , Fezes/parasitologia , Feminino , Humanos , Lactente , Enteropatias Parasitárias/complicações , Masculino , Estado Nutricional , Pais/educação , Vigilância da População , Fatores de Risco , Fatores Socioeconômicos , Inquéritos e Questionários , Banheiros/estatística & dados numéricos , Abastecimento de Água/estatística & dados numéricos
18.
J Physiol ; 482 ( Pt 2): 401-7, 1995 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-7714831

RESUMO

1. A large proportion of sympathetic preganglionic neurones contain nitric oxide synthase. The purpose of this study was to determine the effects of facilitation and inhibition of nitric oxide synthesis within the lower thoracic spinal cord (which contains the majority of renal preganglionic neurones) on renal sympathetic nerve activity (rSNA). 2. In anaesthetized rabbits, rSNA was recorded before and after intrathecal injection (50 microliters of 0.5 M solution) of either L-arginine, a precursor of nitric oxide, or N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, into the lower thoracic spinal cord. Spinal cord sections were also stained for the presence of NADPH diaphorase, a marker of nitric oxide synthesizing neurones. 3. A high density of NADPH diaphorase-containing neurones was found within the intermediolateral cell column of the lower thoracic spinal cord. 4. Intrathecal injection of L-arginine and L-NAME resulted in a large increase (113 +/- 25%) and decrease (43 +/- 8%), respectively, in rSNA. In contrast, injection of the inactive isomers D-arginine and D-NAME had no significant effect on rSNA. 5. The results indicate that endogenous nitric oxide in the lower thoracic spinal cord (1) has a potent excitatory action on renal sympathetic preganglionic neurones, and (2) helps to maintain the tonic activity of renal sympathetic nerves under resting conditions.


Assuntos
Fibras Adrenérgicas/fisiologia , Fibras Autônomas Pré-Ganglionares/fisiologia , Rim/inervação , Óxido Nítrico/fisiologia , Animais , Arginina/análogos & derivados , Arginina/farmacologia , Feminino , Masculino , NADPH Desidrogenase/análise , NG-Nitroarginina Metil Éster , Coelhos , Medula Espinal/química , Medula Espinal/metabolismo
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