Two polyurethanases PueA and PueB are major extracellular lipases partly secreted by the mediation of their cognate ABC exporter AprDEF in Pseudomonas protegens Pf-5.

Two polyurethanases PueA and PueB from Pseudomonas protegens Pf-5 have been reported to have hydrolytic activity against synthetic p-nitrophenyl palmitate of lipase substrate, and PueA may play a more effective role in this activity. However, it is still unknown whether PueA and PueB play similar parts in the lipase activity against natural acylglycerols and achieve the extracellular secretion via their cognate ABC exporter AprDEF. In this study, we investigated these questions through the construction of four markerless deletion mutants in Pf5139 (Δupp derivative of Pf-5), two heterologous co-expression strains and their three control strains in lipase-free Escherichia coli BL21(DE3), and detected their lipase activities by the tributyrin plate assay and the liquid culture assay. The results showed that PueA and PueB, classified as subfamily I.3 lipases, are major extracellular lipases involved in the uptake of oil in Pf-5, and PueA plays a leading role in extracellular lipase activity. In addition, the extracellular secretion of PueA and PueB can be partly mediated via AprDEF in Pf-5 and BL21(DE3). Finally, PueA and PueB are also able to achieve the extracellular secretion without the assistance of AprDEF in Pf-5 and BL21(DE3).

[Interpretations of guideline for the management of diabetes mellitus in the elderly in China (2021 edition)].

Elderly diabetic patients in China accounts for one fourth of the total number of elderly diabetic patients in the world, ranking the first worldwide. In 2021, National Center of Gerontology, Chinese Society of Geriatrics and Diabetes Professional Committee of Chinese Aging Well Association issued China's first guideline on elderly diabetic patients--Guideline for the management of diabetes mellitus in the elderly in China (2021 edition). The present article interprets parts of the important recommendations of the guideline, aiming to facilitate its implementation in clinical practice effectively and improve the clinical prognosis of elderly diabetic patients in our country.

Determination of size distributions of non-spherical pores or particles from single x-ray phase contrast images.

Although x-ray tomography is commonly used to characterize the three-dimensional structure of materials, sometimes this is impractical due either to limited time for data collection (such as in rapidly-evolving systems) or the need to limit the radiation exposure of the sample. In such situations, it is desirable to extract as much information as possible from a more limited data set. In this paper, we describe how to extract the size distribution of non-spherical pores (or, equivalently, particles) from single x-ray phase contrast imaging (XPCI). Because the pores overlap in projection, interpreting the images and extracting quantitative information about the size distribution is non-trivial. In this paper we extend a previously-developed Fourier-based framework for interpreting the speckle pattern of XPCI images from materials with spherical pores to the more challenging case of non-spherical pores. We develop an analytical expression for the XPCI image from a distribution of randomly-oriented ellipsoidal pores, and show that we can use this expression to extract quantitative information about the size distribution from single images. We discuss three approaches to evaluating this expression, corresponding to different assumptions about the nature of the size distribution, and validate our results with simulated XPCI images and experimental data from Berea sandstone.

[Study on the effects of total flavonoids from litchi nucleus on nuclear translocation of nuclear factor-kappa B and related protein expression in rat hepatic stellate cell].

Objective: The effect of total flavonoids of litchi (TFL) on nuclear translocation of nuclear factor-kappa B (NF- kappa B) in rat hepatic stellate cell line (HSC-T6) induced by transforming growth factor - beta 1 (TGF- beta 1) in vitro was studied to explore the mechanism of action of anti-hepatic fibrosis drugs. Methods: HSC-T6 was cultured in vitro, induced by TGFß1 for 24 h, and then treated with TFL at 125, 250 and 500 µg/ml for 48 h. The effect of TFL on NF-κB nuclear translocation in HSC-T6 was observed by confocal laser microscopy. The effects of TFL on the expression of TLR4, p-IκB ɑ, p-NF-κB p65, NF-κB and Collagen I protein were detected by western blot. The expressions of TLR4 and p-NF-κB p65 were detected by immunofluorescence. Data were presented as mean±SEM. Homogeneity test of variance was performed and then followed by one-way analysis of variance (ANOVA). The multiple comparisons between groups were performed by LSD test. P < 0.05 was considered statistically significant. Results: Confocal laser scanning microscopy showed TFL inhibited the nuclear translocation of NF-κB in activated HSC-T6 in a concentration-dependent manner and TFL down regulated the protein expression levels of TLR4, p-IκB ɑ, p-NF-κB p65, NF-κB and collagen I protein in HSC-T6 in a concentration-dependent manner. Conclusion: The mechanism of TFL against hepatic fibrosis may be related to the inhibition of nuclear translocation of NF-κb in the activated HSC-T6 and the expression of TLR4, P-iκbɑ, P-nf-κb p65, NF-κb and collagen I protein in HSC-T6.

Cloning and expression analysis of glucose transporter 4 mRNA in the cold hardiness frog, Rana dybowskii.

BACKGROUND: The Rana dybowskii distribute in northeast region of China which have seasonally cold climates. During winter they survival freezing by biosynthesizing carbohydrate cryoprotectants such as high concentrations glucose into blood and all tissues. The essential role of glucose transporter 4 is a high-affinity glucose transporter, which can increase glucose uptake in cells when it stimulated by insulin. OBJECTIVE: In this study, we analysis the full-length GLUT4 mRNA detect the gene levels of GLUT4 in R. dybowskii main tissues by qPCR during low temperature. RESULTS: We found in heart, fat body, skeletal muscle and skin four tissues all express GLUT4, and the levels of GLUT4 decreased on initial cold exposure stage, 8~12 hours, followed 24 hours it recovered. CONCLUSION: This study we firstly indentified and characterized GLUT4 in amphibious, and provide a novel insight into the role of GLUT4 in cryoprotectant synthesis and cell protection in cold hardiness amphibians.

Molecular variation of Sporisorium scitamineum in Mainland China revealed by internal transcribed spacers.

Sugarcane smut caused by the fungus Sporisorium scitamineum is a worldwide disease and also one of the most prevalent diseases in sugarcane production in mainland China. To study molecular variation in S. scitamineum, 23 S. scitamineum isolates from the 6 primary sugar-cane production areas in mainland, China (Guangxi, Yunnan, Guangdong, Hainan, Fujian, and Jiangxi Provinces), were assessed using internal transcribed spacer (ITS) methods. The results of ITS sequence analysis showed that the organisms can be defined at the genus level, including Ustilago and Sporisorium, and can also differentiate between closely related species. This method was not suitable for phylogenetic relationship analysis of different S. scitamineum isolates and could not provide support regarding their race ascription at the molecular level. The results of the present study will be useful for studies examining the molecular diversity of S. scitamineum and for establishing a genetic foundation for their pathogenicity differentiation and new race detection. In addition, our results can provide useful information for the pathogen selection principle in sugarcane smut resistance breeding and variety distribution.

Identification of smut-responsive genes in sugarcane using cDNA-SRAP.

Sugarcane smut, caused by the fungus Sporisorium scitamineum, is one of the main diseases that affect sugarcane worldwide. In the present study, the cDNA-SRAP technique was used to identify genes that are likely to be involved in the response of sugarcane to S. scitamineum infection. In total, 21 bands with significant differential expression during cDNA-SRAP analysis were cloned and sequenced. Real-time qPCR confirmation demonstrated that expression of 19 of these 21 differential bands was consistent with the expression observed during cDNA-SRAP analysis, with a deduced false positive rate of 9.5%. Sequence alignment indicated that 18 of 19 differentially expressed genes showed homologies from 19% to 100% to certain genes in GenBank, including the following genes: topoisomerase (EU048780), ethylene insensitive (EU048778), and tetraspanin (EU048770). A real-time qPCR assay showed that during 0-72 h after pathogen infection, expression of the topoisomerase and the ethylene insensitive genes was upregulated, whereas expression of the tetraspanin gene was downregulated, identical to the expression patterns observed under salicylic acid treatment. Therefore, all three genes are thought to play a role during S. scitamineum challenge, but with different functions. To our knowledge, this is the first report on the application of cDNA-SRAP in differential gene expression analysis of sugarcane during a sugarcane-S. scitamineum interaction. The results obtained also contribute to a better understanding of the molecular mechanisms associated with sugarcane-S. scitamineum interactions.

Source Areas for the Early Immigration of Sogatella furcifera (Homoptera: Delphacidae) at Xiushan in the Middle Reach of Yangtze River of China.

The spatiotemporal distribution of source areas for the early immigration of the white-backed planthopper, Sogatella furcifera (Horvάth), at Xiushan in the middle reach of Yangtze River of China, was analyzed with HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) and ArcGIS 10.0. The analysis was based on light trap data collected during April-July in 2000-2012. The synoptic meteorology backgrounds during the immigration periods were analyzed by GrADS (Grid Analysis and Display System). The light trap catches of S. furcifera varied monthly and annually. S. furcifera started immigration in Xiushan in early April to early May, whereas the main immigration period was in July. The distribution of the source areas varied monthly, and the core was moved from the south to the north gradually. The main source areas of S. furcifera in May were in southwestern Guangxi and northern Vietnam. The source areas of S. furcifera in June were located in southwestern Guangxi and western Hunan. Additionally, some of the pests were from southeastern Yunnan. The source areas in July were in northwestern Guangxi, southwestern Guizhou, eastern Yunnan, and the transitional parts of Guangxi, Guizhou, and Yunnan. The sum frequencies of southwest and south winds on the 850 hPa isobaric surface of Xiushan of May-July in heavy occurrence years were more than the light occurrence years. The key meteorological factors were suggested to be vertical perturbation, precipitation, and wind shear during S. furcifera immigration periods.

In situ Raman scattering study on a controllable plasmon-driven surface catalysis reaction on Ag nanoparticle arrays.

Control of the plasmon-driven chemical reaction for the transformation of 4-nitrobenzenethiol to p,p'-dimercaptoazobenzene by Ag nanoparticle arrays was studied. The Ag nanoparticle arrays were fabricated by means of nanosphere lithography. By changing the PS particle size, the localized surface plasmon resonance (LSPR) peaks of the Ag nanoparticle arrays can be tailored from 460 to 560 nm. The controlled reaction process was monitored by in situ surface-enhanced Raman scattering. The reaction can be dramatically influenced by varying the duration of laser exposure, Ag nanoparticle size, laser power and laser excitation wavelength. The maximum reaction speed was achieved when the LSPR wavelength of the Ag nanoparticle arrays matched the laser excitation wavelength. The experimental results reveal that the strong LSPR can effectively drive the transfer of the 'hot' electrons that decay from the plasmon to the reactants. The experimental results were confirmed by theoretical calculations.

Antibacterial silver-containing silica glass prepared by ion implantation.

Recently, there is much interest in nanocomposites consisting of metal nanoparticles dispersed in dielectric matrix. Silver is the first candidate used in antibacterial research. In the present study, sliver-containing silica glass is prepared by ion implantation. The bactericidal properties of Ag-implanted samples are investigated using E. coli. The implanted samples are characterized by optical absorption spectroscopy, atomic force microscopy and transmission electron microscopy. The size and position of the silver nanoparticles formed by ion implantation can be optimized by adjusting the implanted process parameters. All the implanted samples show antibacterial properties. But the samples with silver nanoparticle-enriched surfaces possess excellent antibacterial properties in comparison with other implanted samples. This indicates that ion implantation is a potential method for synthesizing antibacterial biomaterials.

ELF1 activated long non-coding RNA CASC2 inhibits cisplatin resistance of non-small cell lung cancer via the miR-18a/IRF-2 signaling pathway.

OBJECTIVE: Chemoresistance is the leading cause of recurrence in non-small cell lung cancer (NSCLC). The long non-coding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2) inhibits the tumorigenesis of various cancers. However, the regulatory function of CASC2 on the chemoresistance of NSCLC remains unclear. PATIENTS AND METHODS: The levels of CASC2 and miR-18a in cisplatin (DDP)-resistant NSCLC tissues and cell lines were evaluated by quantitative Polymerase Chain Reaction (qPCR). The role of low CASC2 levels on overall survival in patients with NSCLC was tested using the log-rank test. The Chi-squared test was used to assess the relation between CASC2 expression and clinicopathological features of NSCLC patients. Cell Counting Kit-8 (CCK-8) assays tested the cell proliferation of cisplatin-resistant NSCLC cells (H226/DDP and A549/DDP). The underlying regulatory mechanism between CASC2 and miR-18a or miR-18a and interferon regulatory factor 2 (IRF-2) was predicted by bioinformatics and verified by a Dual-Luciferase reporter assay, RNA transfection, qPCR, and Western blotting. Chromatin immunoprecipitation (ChIP) assay was done to exam the relation between E74 like factor 1 (ELF1) and CASC2 gene. Mice xenografts were applied to exam the function of CASC2 on chemosensitivity of cisplatin of NSCLC cells in vivo. RESULTS: Low CASC2 expression is more likely to present in patients with advanced TNM stage (IV), cisplatin-resistance, and poor overall survival. The expression of CASC2 sharply decreased in cisplatin-resistant NSCLC tissues and cell lines (H226/DDP and A549/DDP). CASC2 overexpression strongly inhibited proliferation, migration, and invasion of cisplatin-resistant NSCLC cells (H226/DDP and A549/DDP) in vitro and inhibited tumor growth in vivo. Besides, CASC2 repressed miR-18a function by binding to the complementary sites of miR-18a as competing endogenous RNAs (ceRNAs). MiR-18a released by the declining expression of CASC2 reduced the protein concentration of IRF-2 in NSCLC cells. Furthermore, the transcription factor ELF1 was found to be promotor of CASC2 and increased its levels in cisplatin-resistant NSCLC cells. CONCLUSIONS: IRF-2 expression mediated by the ELF1/CASC2/miR-18a axis is markedly associated with the proliferation, migration, and invasion of cisplatin-resistant NSCLC, resulting in inferior survival. These findings suggest that this regulatory axis may serve as a novel therapeutic target in NSCLC.

Glucose, metformin, and AICAR regulate the expression of G protein-coupled receptor members in INS-1 beta cell.

Glucagon-like peptide-1 receptor (GLP-1R), glucose-dependent insulinotropic polypeptide receptor (GIPR), and G protein-coupled receptor 40 (GPR40) are members of G protein-coupled receptors (GPCR) family. They are abundantly expressed in islet beta cells, and mediate effects of incretins and fatty acids in beta cells. Glucose and 5-AMP-activated protein kinase (AMPK) are known to be involved in the regulation of beta cell function. Metformin and the potential therapeutic drug for type 2 diabetes, 5-amino-4-imidazolecarboxamide riboside (AICAR), are both known activators of AMPK. Here we studied the effects of glucose, metformin, and AICAR on the expression of GPCR in INS-1 beta cell. INS-1 beta cells were supplemented with different concentrations of glucose, metformin, or AICAR. The expressions of GLP-1R, GIPR, GPR40, and a nuclear transcription factor - peroxisome-proliferator activated receptor alpha (PPARalpha) - were analyzed by real-time RT-PCR and immunoblotting. The time-course of the mRNA degradation of these receptors was also monitored by applying actinomycin D to cells. We demonstrated that the expressions of GLP-1R, GIPR, and PPARalpha were downregulated when INS-1beta cells were treated with glucose, while their expressions were upregulated when treated with metformin or AICAR. Glucose, metformin, or AICAR treatment had no obvious effect on the expression of GPR40. These results indicate that glucose, metformin, and AICAR regulated the expressions of incretin receptors and PPARalpha, but not GPR40 in beta cells. Whether AMPK is a key regulator of these factors mediated receptor regulation remains to be investigated further.

Investigation of the anti-fungal activity of coptisine on Candida albicans growth by microcalorimetry combined with principal component analysis.

AIMS: This study investigated the anti-fungal activity of coptisine on Candida albicans growth. METHODS AND RESULTS: The metabolic power-time curves of Candida albicans growth at 37 degrees C affected by coptisine were measured by microcalorimetry using an LKB-2277 Bioactivity Monitor with stop-flow mode. Then, the diameter of inhibitory zones in the agar layer was observed using agar cup method, and the minimal inhibitory concentration (MIC) of coptisine on Candida albicans growth was determined by serial dilution method. From the principal component analysis on nine quantitative parameters obtained from the power-time curves, we could easily evaluate the anti-fungal activity of coptisine by analysing the change of values of the main two parameters, growth rate constant k and maximum power output in the log phase P(m, log). The results showed that coptisine had strong anti-fungal activity: at a low concentration (45 microg ml(-1)) began to inhibit the growth of Candida albicans and at a high concentration (500 microg ml(-1)) completely inhibited Candida albicans growth. Coptisine gave big inhibitory zones with diameters between 11 and 43 mm within test range, and the MIC of it was 1000 microg ml(-1). CONCLUSIONS: Coptisine had strong anti-fungal activity on Candida albicans growth. The method of microcalorimetry applied for the assay of anti-fungal activity of coptisine was quantitative, sensitive and simple. SIGNIFICANCE AND IMPACT OF THE STUDY: This work will provide useful information for the development of chemical biology policy in the use of anti-microbials in food and drug production.

Effect of emodin on Candida albicans growth investigated by microcalorimetry combined with chemometric analysis.

Using the 3114/3115 thermal activity monitor (TAM) air isothermal microcalorimeter, ampoule mode, the heat output of Candida albicans growth at 37 degrees C was measured, and the effect of emodin on C. albicans growth was evaluated by microcalorimetry coupled with chemometric methods. The similarities between the heat flow power (HFP)-time curves of C. albicans growth affected by different concentrations of emodin were calculated by similarity analysis (SA). In the correspondence analysis (CA) diagram of eight quantitative parameters taken from the HFP-time curves, it could be deduced that emodin had definite dose-effect relationship as the distance between different concentrations of it increased along with the dosage and the effect. From the principal component analysis (PCA) on eight quantitative parameters, the action of emodin on C. albicans growth could be easily evaluated by analyzing the change of values of the main two parameters, growth rate constant k (2) and maximum power output P(2)(m). The coherent results of SA, CA, and PCA showed that emodin at different concentrations had different effects on C. albicans growth metabolism: A low concentration (0-10 microg ml(-1)) poorly inhibited the growth of C. albicans, and a high concentration (15-35 microg ml(-1)) could notably inhibit growth of this fungus. This work provided a useful idea of the combination of microcalorimetry and chemometric analysis for investigating the effect of drug and other compounds on microbes.

Randomised clinical trial: Tong-Xie-Yao-Fang granules versus placebo for patients with diarrhoea-predominant irritable bowel syndrome.

BACKGROUND: Tong-Xie-Yao-Fang (TXYF) is a Chinese herbal formula for treating chronic diarrhoea accompanied by abdominal pain. The results were inconsistent in previous trials examining its effect. AIM: To study the efficacy of TXYF granules for treating diarrhoea-predominant irritable bowel syndrome (IBS-D). METHODS: We performed a double-blind, placebo-controlled randomised trial and enrolled 160 participants with IBS-D. The participants had VAS scores ≥3 cm in IBS-D global symptoms and ≥2 days in a week with abdominal pain and loose stools (Bristol score 5, 6 or 7). They were randomly assigned to received TXYF or placebo during a treatment period of 4 weeks, and they were followed up for 8 weeks after treatment. The primary outcome was adequate relief of IBS-D global symptoms for at least 2 of 4 weeks during weeks 1-4. Secondary outcomes included mean weekly VAS scores of IBS-D major symptoms, mean weekly stool frequency, mean weekly Bristol score, and adverse events. RESULTS: 155 of 160 patients completed the trial. We found a significantly higher rate of adequate relief of global symptoms in TXFY group during weeks 1 to 4 (57.5% vs 37.5%, χ2 = 5.6391, P = 0.017); logistic regression analysis showed a similar result (OR 2.2, 95% CI 1.2-4.4, P = 0.016). Most of the secondary outcomes showed superiority of TXYF over placebo in weekly assessment from week 3 to week 7. The adverse event rate was low in both groups (3.8% vs 3.8%, P = 1.000). CONCLUSION: During a 4 week trial, TXFY granules were superior to placebo in controlling symptoms of IBS-D.

Role of Na(+)/H(+) exchanger during ischemia and preconditioning in the isolated rat heart.

The role of the Na(+)/H(+) exchanger in ischemia, reperfusion, and preconditioning was investigated in isolated perfused rat hearts. Contractile function, [Na(+)](i), and pH(i) were measured; ischemic damage was assessed by the recovery of developed pressure (DP) on reperfusion. After 30 minutes of ischemia, DP recovered to only 14+/-4% of preischemic control. In contrast, after preconditioning (3x5-minute periods of ischemia) followed by 30 minutes of ischemia, DP recovered to 75+/-4%. Hearts treated with the Na(+)/H(+) exchange inhibitor 5-(N-methyl-N-isobutyl)amiloride (MIA) also showed an enhanced recovery after ischemia (DP 62+/-9%). Treatment with a low concentration of tetrodotoxin (TTX, 100 nmol/L), which blocks the persistent component of the Na(+) current, had a small beneficial effect on recovery (DP 37+/-8%). Thirty minutes of ischemia caused a small [Na(+)](i) rise (3.2+/-0.9 mmol/L); reperfusion resulted in a further [Na(+)](i) increase (+11.9+/-2.5 mmol/L), which partially recovered over 30 minutes. Preconditioning did not change the [Na(+)](i) rise during ischemia but abolished the large [Na(+)](i) rise on reperfusion, and [Na(+)](i) instead fell (-3.6+/-1.3 mmol/L). In the presence of MIA, the [Na(+)](i) rise was unchanged from ischemia only; on reperfusion, [Na(+)](i) fell (-3.7+/-0.9 mmol/L), similar to the preconditioned hearts. TTX abolished the [Na(+)](i) rise during ischemia (+0.3+/-0.7 mmol/L), and the increase on reperfusion was similar to ischemia only. We conclude that the rise of [Na(+)](i) during ischemia is caused by Na(+) entry through persistent Na(+) channels. The rise of [Na(+)](i) on reperfusion is caused by activation of the Na(+)/H(+) exchanger and is blocked by MIA and by preconditioning. It is known that the Na(+)/H(+) exchanger is inhibited during ischemia; the present result suggests that this inhibition is prolonged into the early part of reperfusion by preconditioning. To test this hypothesis, we measured the time course of pH(i) recovery after ischemia and preconditioning. Preconditioning slowed the rate of pH(i) recovery after ischemia, providing further support for the hypothesis that preconditioning inhibits the Na(+)/H(+) exchanger during early reperfusion. This inhibition of the Na(+)/H(+) exchanger during reperfusion prevents Na(+) entry, and therefore Ca(2+) loading, and is part of the protective pathway involved in preconditioning.

Activity of the Na(+)/H(+) exchanger is critical to reperfusion damage and preconditioning in the isolated rat heart.

OBJECTIVE: Removal of protons from the heart during ischemia and/or reperfusion by the cardiac Na(+)/H(+) exchanger (NHE1) leads to Na(+) entry; this causes Ca(2+) influx and is thought to contribute to ischemic and/or reperfusion damage. The extent to which Na(+) enters during ischemia as opposed to reperfusion is disputed and has important implications for the therapeutic use of NHE1 inhibitors as protection against ischemic damage. Preconditioning has recently been proposed to inhibit NHE1 during reperfusion. The objective of the present study was to determine the activity of NHE1 during ischemia, reperfusion and following preconditioning. METHODS: The experiments were on isolated perfused rat hearts in which left ventricular developed pressure (LVDP) and intracellular sodium and pH were measured. RESULTS: LVDP following 30 min of ischemia recovered to 14+/-3% of pre-ischemic level. Application of the NHE1 inhibitor HOE 642 during ischemia and reperfusion improved recovery of LVDP to 77+/-9%. When HOE was applied at the moment of reperfusion the recovery of LVDP was reduced to 54+/-6%. To overcome possible delays in the delivery of HOE, the drug was applied at 28 min of ischemia; under these conditions recovery of LVDP (71+/-7%) was not significantly different to HOE throughout ischemia and reperfusion. HOE had no effect on the recovery of preconditioned hearts. NHE1 activity was assessed by the [Na(+)](i) and pH(i) changes in response to brief exposure to Na(+) lactate (NaL). In control hearts, activity of NHE1 caused a pH(i) recovery of 0. 034+/-0.007 pH units and was associated with a [Na(+)](i) rise of 7. 5+/-0.5 mmol/l. After 5-min reperfusion following ischemia, NaL application caused a pH(i) recovery (0.046+/-0.007) and a larger [Na(+)](i) rise (15.8+/-0.6 mmol/l). After 5-min reperfusion of preconditioned hearts, NaL application caused a smaller recovery pH recovery (0.013+/-0.002) and a smaller [Na(+)](i) rise (4.2+/-0.5 mmol/l). CONCLUSIONS: These findings suggest that NHE1 is activated in early reperfusion after ischemia but inhibited during early reperfusion in preconditioned hearts. Overall our results point to a critical period of activity of NHE1 in early reperfusion which is inhibited by preconditioning.

Alpha 2-adrenoceptor agonists enhance vasoconstrictor responses to alpha 1-adrenoceptor agonists in the rat tail artery by increasing the influx of Ca2+.

1. The alpha 2-adrenoceptor agonists TL99 (2-(N N-dimethyl)amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene) and UK14304 (5-bromo-6-[2-imidazoline-2-yl-aminol]-quinoxaline), in concentrations that are less than 1% of those producing vasoconstriction, enhance vasoconstrictor responses to noradrenaline and phenylephrine in isolated perfused preparations of the rat tail artery. 2. The enhancing effect was abolished when Ca2+ was absent and by the calcium channel blocking drug diltiazem. 3. alpha 2-Adrenoceptor agonists had no effect on the component of the responses to noradrenaline and phenylephrine that is attributable to mobilization of intracellular Ca2+, but enhanced the component attributable to influx of extracellular Ca2+. 4. These results suggest that the enhancing effect of alpha 2-adrenoceptor agonists on responses of the rat tail artery to alpha 1-adrenoceptor agonists involves an increase in Ca2+-influx into smooth muscle cells through Ca2+ channels that are opened when alpha 2-adrenoceptors are activated.

Alpha 2-adrenoceptor agonists enhance responses to certain other vasoconstrictor agonists in the rat tail artery.

1. The effects of the alpha2-adrenoceptor agonists clonidine, rilmenidine, TL99 and UK14304 on the vasoconstrictor response to sympathetic nerve stimulation and on the concentration-response curves to noradrenaline and phenylephrine were compared in two isolated, perfused vascular tissues: the rat tail artery (which has both postjunctional alpha 1- and alpha 2-adrenoceptors), and the rabbit ear artery (in which only alpha 1-adrenoceptors are present postjunctionally). 2. In the rabbit ear artery, the first observable effect of alpha 2-adrenoceptor agonists was inhibition of vasoconstrictor responses to sympathetic nerve stimulation. This occurred with concentrations of the alpha 2-adrenoceptor agonists which were far below those producing vasoconstriction. Responses to noradrenaline were not affected. 3. In contrast, in the rat isolated perfused tail artery, alpha 2-adrenoceptor agonists, in concentrations that produced no other observable effects, enhanced the vasoconstrictor responses to sympathetic nerve stimulation and to noradrenaline. Much higher concentrations of alpha 2-adrenoceptor agonists produced vasoconstriction in most preparations and only then reduced the response to sympathetic nerve stimulation. The enhancing effect of alpha 2-adrenoceptor agonists was blocked by idazoxan, but not by prazosin. 4. Vasoconstrictor responses in the rat tail artery to the relatively selective alpha 1-adrenoceptor agonist phenylephrine were enhanced by alpha 2-adrenoceptor agonists. The enhancement of the response to phenylephrine was greater than that to the mixed alpha 1- and alpha 2-adrenoceptor agonist noradrenaline. 5. Vasoconstrictor responses in the rat tail artery to vasopressin, ATP and KCl, like those to alpha 1-adrenoceptor agonists, were enhanced by alpha 2-adrenoceptor agonists.2+owever, vasoconstrictor responses to

Characterization of the tachykinin NK2 receptor subtype in the rabbit pulmonary artery.

Contractile responses to neurokinin A (NKA), neuropeptide gamma(NP gamma), and the NK2 receptor-selective analogs [Lys5,MeLeu9,Nle10]NKA(4-10) and MDL 28,564 were determined in the endothelium-denuded rabbit pulmonary artery. Responses to NKA, NP gamma, and [Lys5,MeLeu9,Nle10]NKA(4-10) were antagonized by the NK2 receptor antagonist MDL 29,913, with pA2 values of 6.67, 6.46, and 7.32, respectively. Autoradiographic studies failed to demonstrate any specific binding sites for [125I]-iodohistidyl NKA (INKA) over the pulmonary artery. These data suggest the presence in rabbit pulmonary artery of an unusual "nonclassical" NK2 receptor subtype, which appears to lack affinity for INKA.