Possible role of dopamine-beta-hydroxylase in the regulation of norepinephrine biosynthesis in rat brain.

In Experiment 1, the dose-response effects of three dopamine-beta-hydroxylase (DBH) inhibitors (diethyldithiocarbamate, FLA-63 and U-14, 624) on the endogenous levels of norepinephrine and dopamine in pons-medulla of rat brain were determined. In Experiment 2, the effect of low doses of diethylithiocarbamate (2.5 to 120 mg/kg) on the level of norepinephrine-3H produced from dopamine-H3 was determined. The data obtained by extrapolation of the curves in both experiments provided an estimation of the in vivo level of DBH activity and suggested that it was not present in excess. Finally, in Experiment 3, the three DBH inhibitors reduced self-stimulation (a behavior dependent upon catecholamines) in a dose-related manner and intraventricular injections of 1-norepinephrine reinstated normal rates of self-stimulation. The results from the three experiments are consistent with the idea that DBH is involved in the regulation of norepinephrine biosynthesis. The relationship of this finding to our earlier report of a deficit of DBH in post-mortem brains of schizophrenics is discussed.     

The relaxing effect of aluminum and lanthanum on rat and human gastric smooth muscle in vitro

M. HAVA and A. HURWITZ, The relaxing effect of aluminum and lanthanum on rat and human gastric smooth muscle in vitro, European J. Pharmacol. 22 (1973) 156–161.Aluminum and lanthanum relaxed and partly blocked the acetylcholine-evoked contractions of rat and human stomach smooth muscle strips. In the perfused isolated rat stomach, intraluminal administration of 3 ml of 5 mM AlCl₃ or LaCl₃ caused a reversible reduction of contractions evoked by serosal administration of acctylcholine in the organ bath after a 90-min delay. The concentration of aluminum in solution in rat stomachs after administration of aluminum hydroxide in vivo was 0.015 M. This concentration was 30 times that which blocked contraction of isolated muscie strips and 3 times the concentration effective in perfused rat stomachs in vitro.     

The effect of adrenergic agonists and cyclic AMP on the Na+/K+ ATPase activity of brown adipose tissue.

The Na+/K+ ATPase activity of membrane fractions prepared from brown adipose tissue of cold-acclimated rats could be stimulated by addition of any one of the following: norepinephrine, isoproterenol, cyclic AMP or phenylephrine. These results are consistent with the proposal that in the intact brown adipocyte, the norepinephrine-induced stimulation of the Na+/K+ membrane pump is associated with alpha- as well as beta-adrenergic pathways and is, in part, mediated via cyclic AMP.     

Chronic dopa treatment: effect on the concentration of norepinephrine in the hearts and brains of rats

Chronic L-dopa treatment in rats had no significant effect on brain norepinephrine levels after 21 days of oral treatment. In contrast, cardiac norepinephrine was found to be markedly reduced. While dopamine was found to accumulate in heart at earlier times, twelve hours after L-dopa dopamine concentrations were insufficient to compensate for the observed norepinephrine depletion.     

不同给药方式对P2X_1受体介导大鼠肠系膜动脉收缩反应的影响

目的研究不同方式给予α,β-MeATP对肠系膜动脉P2X1受体介导血管收缩反应的影响。方法制备大鼠离体肠系膜动脉环标本,采用非累积给药法和单浓度给药法两种方式给予α,β-MeATP,记录药物诱发的等长收缩反应。结果两种给药方式给予α,β-MeATP(10-7-10-4mol·L-1)均可使大鼠离体肠系膜动脉产生浓度依赖性收缩反应。以KCl最大收缩反应或以标本湿重标化α,β-MeATP诱发的收缩反应时,α,β-MeATP单浓度给药的收缩反应均大于非累积给药(P<0.01)。以标本湿重标化时,10-4mol·L-1浓度α,β-MeATP诱发的收缩反应分别是(0.73±0.10)g·mg-1(单浓度组)和(0.38±0.05)g·mg-1(非累积组);以KCl最大收缩反应标化时,分别是(53.17±6.0)%(单浓度组)和(36.78±5.71)%(非累积组)。在α,β-MeATP非累积给药组120mmol·L-1KCl诱发的动脉收缩反应小于单浓度给药组和NA对照组(P<0.01)。结论在大鼠肠系膜动脉,非累积给予α,β-MeATP降低P2X1受体介导的收缩反应以及高钾诱发的收缩反应,该给药方式可能导致错误的实验结论 。     

肺成纤维细胞在肺纤维化进程中的作用

肺纤维化(pulmonary fibrosis,PF)是一种严重的肺间质疾病,主要病理特点是早期的弥漫性肺泡炎,后期大量成纤维细胞病理性增殖转型及细胞外基质(extracellular matrix,ECM)进行性异常积聚并取代正常的肺组织结构。其发病原因很多,如病原微生物、粉尘、药物、化学制剂等多种因素均可诱导产生肺纤维化,但发病机制尚不清楚。在其发生过程中,肺成纤维细胞(fibroblast,FB)起着重要的促进作用,主要通过自身的异常增殖与转型,大量分泌细胞外基质直接触发PF和作用于上皮细胞及一些炎症细胞间接参与PF进程。该文通过整理成纤维细胞在PF中的作用,进一步了解肺纤维化的发病机制。     

Involvement of central alpha-adrenoceptors in the hypotensive and bradycardic effects of (--)-delta 9-trans-tetrahydrocannabinol.

I.v. administration of (--)-delta9-trans-tetrahydrocannabinol (delta 9-THC) to chloralose-anesthetized cats produced a decrease in blood pressure and heart rate. Studies conducted to investigate the mechanism of these changes revealed that the hypotensive and bradycardic effects of delta 9-THC (0.1 mg/kg, i.v.) could be significantly antagonized following intraventricular (i.v.t.) perfusion with alpha-adrenergic receptor blocking agent phentolamine, while a larger dose of delta 9-THC (0.25 mg/kg, i.v.) still produced significant hypotension and bradycardia. I.v.t. perfusion of phentolamine (100 mug/min for 30 min) caused a fall in blood pressure and heart rate which were reversible and produced blockade of central alpha-adrenergic receptors. These results provide evidence for the involvement of central alpha-adrenergic receptors in the hypotensive and bradycardic actions of delta 9-THC and indicate that other receptor mechanisms may also be involved in mediating these responses observed following administration of delta 9-THC.     

Effects of vasoactive agents on oxygen uptake in portal venous smooth muscle

The studies concerned the effects of epinephrine, norepinephrine, phenylephrine, acetylcholine and K⁺ ions, in doses inducing maximal contraction on oxygen consumption of isolated rat portal veins. All the agonists tested stimulated the rate of O₂ uptake, whereas high K⁺ did not. After specific blockade of α-adrenoceptors, the effects of epinephrine and norepinephrine on O₂ consumption were not affected, whilst those of phenylephrine were abolished, and β-adrenoceptor blockade suppressed the metabolic effect of epinephrine and norpinephrine. Acetylcholine was the agonist that most elevated O₂ consumption; atropine blocked both contractile and metabolic effects of this drug. It appears that there is a clear dissociation between contractile and metabolic actions of some pharmacological agents, and a question is posed concerning phenylephrine and acetylcholine effects. Results with K⁺ suggest that different metabolic pathways might be involved in the activation and maintenance of drug-induced contraction in smooth muscle.     

The protective effect of phentolamine against cardiac arrhythmias in the rat

Norepinephrine was given by continous infusion at a rate of 80 μg/kg/min for 2 min. Norepinephrine caused the appearance of cardiac arrhythmias, primarily ventricular extrasystoles. The prior administration of phentolamine, even in a dose which did not antagonize the pressor effect of norepinephrine, prevented extrasystole production by norepinephrine. Tolazoline and yohimbine, in doses which did not affect the vasopressor action of norepinephrine, also suppressed extrasystole production. It is concluded that the antiarrhythmic effect of phentolamine, does not require antagonism of α-adrenoceptors of the type found in the vasculature, but may involve effects on a different type of a α-adrenoceptors in the heart.     

The use of the slowly degradable analog, alpha, beta-methylene ATP, to produce desensitisation of the P2-purinoceptor: effect on non-adrenergic, non-cholinergic responses of the guinea-pig urinary bladder

alpha, beta-Methylene ATP has advantages over ATP in producing desensitisation of the P2-purinoceptor since it is degraded more slowly than ATP and does not initiate synthesis of prostaglandins. Following desensitisation of the excitatory P2-purinoceptors in the guinea-pig urinary bladder, the excitatory responses to non-adrenergic, non-cholinergic nerve stimulation were abolished, while those to acetylcholine and histamine were little affected. This result is consistent with the purinergic nerve hypothesis.     

The effect of three H2 receptor antagonists on the disposition of cyclosporin a in the in situ perfused rat liver model

The in situ, perfused rat liver model was used to investigate the effect of three H₂ receptor antagonists on the disposition of cyclosporin A (CyA) and the major human metabolite, AM1. Perfusion experiments, using standard techniques, were carried out on four groups (one control and three H₂-receptor antagonist-treated groups) of male Sprague-Dawley rats (300–350 g). All animals received CyA, 2.5 mg; the three treated groups received cimetidine (8 mg), ranitidine (3 mg), or famotidine (0.4 mg). Perfusated and bile samples were collected and assayed for CyA, AM1, and the H₂ receptor antagonists by HPLC. Results indicated that CyA perfusate concentrations in the controls and cimetidine and ranitidine-treated groups were not significantly different, although levels in the famotidine group were significantly higher at all times (p<0.05), except 30 min, compared to the controls. However, examination of the AM1 perfusate and bile data and the apparent metabolic clearance data indicated that CyA metabolism was still occurring, despite the presence of the H₂ receptor antagonist. It is suggested that the absence of a interaction may be attributed to a lack of specificity of the H₂ receptor antagonists for CYP3A, the isoenzyme responsible for CyA metabolism.     

The role of neurotransmitters in stress-induced antinociception (SIA)

The role of the neurotransmitters, norepinephrine, dopamine and serotonin in stress-induced antinociception (SIA) was examined by altering neurochemical tone with appropriate pharmacological tools. Quipazine (15.0 mg/kg, IP) a serotonin agonist, increased the peak and duration of antinociception following stress and BC-105 (3.0 mg/kg, IP), a serotonin antagonist, blocked the increase of tail-flick latency following stress. Clonidine (0.1 mg/kg, SC) an alpha 2 agonist, markedly decreased SIA whereas phenoxybenzamine (2.5 mg/kg, IP), an alpha 1 antagonist, increased the peak and duration of SIA. When dopaminergic tone was increased with apomorphine (0.05 mg/kg, SC) the increase of tail-flick latency after stress was markedly attenuated whereas blockage of dopamine receptors with haloperidol (2.5 mg/kg, IP) increased the peak and duration of SIA. Alterations of serotonergic, but not noradrenergic or dopaminergic, tone had similar effects on increased latency in tail-flick test produced by brain stimulation produced analgesia (SPA), morphine and SIA. These data support the hypothesis that alterations in tail-flick latency involves a serotonergic system.     

Metabolism of 14C-2',3'-dideoxyinosine by the in situ perfused rat liver preparation

The metabolism and biliary excretion of 14C-dideoxyinosine (14C-ddI) has been investigated using the in situ perfused rat liver (PRL) preparation. After 2 h of perfusion through the liver, approximately 70-75 per cent of the total 14C-radiolabel was recovered in the perfusion medium, less than 1 per cent was excreted in bile and 15-18 per cent was retained in the liver. Hepatic clearance of ddI was 1.5 +/- 0.1 ml min-1 and half-life for the elimination of ddI from the medium was 22.9 +/- 2.0 min (n = 3). Hepatic extraction was estimated to be 7.5 per cent. HPLC analysis of the effluent perfusate indicated that ddI was metabolized to hypoxanthine, xanthine, uric acid, and to a polar metabolite which was tentatively identified as allantoin. Approximately 60-65 per cent of the ddI dose was converted to allantoin after 2 h of perfusion. Of the other three metabolites, uric acid levels increased to 20-30 per cent of the dose after 45 min and declined to about 5 per cent of the dose by the end of the perfusion period. Levels of hypoxanthine and xanthine were low and both compounds were not detected in the perfusate after 45 min post-infusion. In bile, the major peak, which accounted for about 50 per cent of the 14C-radiolabel co-eluted with the putative metabolite, allantoin (0.4 per cent of the dose). Uric acid (0.06 per cent of the dose) was the only other metabolite detected in bile. These results suggest that biliary excretion is a minor pathway for the elimination of ddI. Furthermore, ddI is rapidly cleared and metabolized by the liver to hypoxanthine, xanthine, uric acid, and to allantoin.     

罗格列酮对重症急性胰腺炎合并肺损伤的防治作用

目的 研究抵抗素在过氧化物酶增殖物激活受体(PPAR-γ)激动剂(罗格列酮)对大鼠重症急性胰腺炎(SAP)及其合并肺损伤防治中的作用及其作用机制.方法 用ELISA法检测大鼠血清淀粉酶(AMY)、抵抗素、肿瘤坏死因子(TNF-α)、白细胞介素-1β(IL-1β)和C.反应蛋白(CRP)的水平变化,检测肺组织髓过氧化物酶(MPO)、肺湿/干重比值、胰腺/体质量比值、胰腺和肺组织病理变化;免疫组化检测胰腺组织中抵抗素的表达;实时定量PCR法检测胰腺组织中抵抗素mRNA的水平.结果 罗格列酮预防组和治疗组大鼠血清AMY、抵抗素、TNF-α、IL-1B和CRP水平较SAP组均明显下降(均P＜0.01),预防组和治疗组与对照组相比均有明显升高(均P＜0.01),预防组和治疗组之间相比较有所变化,但两者之间无统计学意义;罗格列酮预防和治疗组胰腺/体质量比、胰腺病理评分、肺组织MPO含量和肺的病理评分较SAP组均明显降低(均P＜0.01);对照组、SAP组、预防组和治疗组大鼠的胰腺组织抵抗素mRNA相对表达量(RQ值)较SAP组明显降低(均P＜0.01),而与对照组相比较均明显升高(P＜0.01),但预防组与治疗组之间差异无统计学意义.结论 罗格列酮对SAP及合并肺损伤有明显的预防和治疗作用.     

Slit2-N inhibits PDGF-induced migration in rat airway smooth muscle cells: WASP and Arp2/3 involved

Background

Slit2 has been reported to be implicated in many kinds of cell migration. However little is known about the effect of Slit2 on airway smooth muscle cell migration. This study was to detect the expression of Slit2 in rat airway smooth muscle (RASM) cells stimulated by platelet-derived growth factor (PDGF) and characterized the effect of Slit2-N on PDGF-induced migration of RASM cells in vitro.

Methods

mRNAs of Slit-Robo in RASM cells were examined by RT-PCR, and the effect of exogenous Slit2-N at different doses on PDGF-induced migration of RASM cells were examined by transwell and scrape-wound assays. Actin filaments (F-actin) were stained with rhodamine-conjugated phalloidin and the levels of protein expression were detected by western blot.

Results

RASM cells were identified to express Slit2, Slit3, Robo1, Robo2 and Robo4 in vitro. Slit2-N caused a time- and dose-dependent inhibition of cell proliferation, while had no significantly effect on cell apoptosis. Slit2-N pretreatment attenuated the elongated morphologic characteristics, reduced lamellipodia formation, inhibited actin rearrangement and cell migration induced by PDGF. PDGF-induced increase of WASP and Arp2/3 proteins were dramatically inhibited by 100 ng/ml Slit2-N.

Conclusion

Slit2-N inhibits RASM cells migration at least partly through attenuating the expressions of WASP and Arp2/3, inhibiting actin rearrangement in vitro. The results contribute to provide new insights into the pathogenesis of airway remodeling in asthma and may be helpful for development of effective treatments.     

The role of intraspinal adenosine A1 receptors in sympathetic regulation

Using a splanchnic nerve-spinal cord preparation in vitro, we have previously demonstrated that tonic sympathetic activity is generated from the thoracic spinal cord. Here, we sought to determine if adenosine receptors play a role in modulating this spinally generated sympathetic activity. Various adenosine analogs were applied. N6-Cyclopentyladenosine (CPA, adenosine A1 receptor agonist) and 5'-N-ethylcarboxamidoadenosine (NECA, adenosine A1/A2 receptor agonist) reduced, while N6-[2-(4-aminophenyl)ethyl]adenosine (APNEA, non-selective adenosine A3 receptor agonist) did not alter sympathetic activity. The inhibitory effect of CPA or NECA on sympathetic activity was reversed by 8-cyclopentyltheophylline (CPT, adenosine A1 receptor antagonist) or abolished by CPT pretreatment. In the presence of 3,7-dimethyl-1-propargylxanthine (DMPX, adenosine A2 receptor antagonist), sympathetic activity was still reduced by CPA or NECA. Sympathetic activities were not changed by applications of the more selective adenosine A2 or A3 receptor agonists or antagonists, including 4-[2-[[6-amino-9-(N-ethyl-beta-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid (CGS21680), 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM241385), 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Chloro-IB-MECA), and 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS1191). These findings exclude a possible involvement of A2 or A3 receptors in sympathetic regulation at the spinal levels. Interestingly, CPT alone did not affect sympathetic activity, suggesting that adenosine A1 receptors are endogenously quiescent under our experimental conditions. We conclude that intraspinal adenosine A1 receptors may down-regulate sympathetic outflow and serve as a part of the scheme for neuroprotection.     

依那普利对肾性与自发性高血压大鼠左心室Eno1及GSTM2表达的影响

目的观察依那普利对肾性与自发性高血压大鼠左心室α-烯醇化酶(α-enolase,Eno1)及谷胱甘肽-s-转移酶,μ2(glutathione-s-transferase,μ2,GSTM2)表达的影响。方法实验共分5组:(1)对照组;(2)两肾两夹高血压大鼠组;(3)两肾两夹高血压大鼠+依那普利组;(4)自发性高血压大鼠组;(5)自发性高血压大鼠+依那普利组。检测各组大鼠血压及左室重量指数,行超声心动图检查,并运用Western blot检测各组大鼠左心室Eno1、GSTM2及β-肌球蛋白重链(β-myosin heavy chain,β-MHC)的表达情况。结果两肾两夹及自发性高血压大鼠血压与左室重量指数均明显高于对照组,依那普利治疗后,其左心室肥厚均得到明显逆转。与两肾两夹组相比,Eno1在自发性高血压大鼠中的表达明显上调;与对照组相比,GSTM2在自发性高血压大鼠中的表达明显下调,而两肾两夹组无变化,经依那普利治疗后,二者的表达变化均未得到明显逆转;β-MHC在两种模型中的表达均上调,而依那普利治疗后,β-MHC在二者中的表达均明显下调。结论依那普利能明显逆转β-MHC在两种模型中的差异表达,但不能逆转Eno1和GSTM2在二者中的差异表达。     

β-受体阻断剂对异丙肾上腺素提高心肌耗氧量作用的影响

The blockade effect of β-receptor blockers bupranolol and ACC9089 on the increase of heart muscle oxygen consumption by isoprenaline was studied according to Castellucci's method with Warburg's apparatus on thin slices of swine heart muscle instead of the rabbit heart muscle. The results showed that Bupranolol was about 2.5 times more stronger than practolol and about 2 times more stronger than ACC-9089 to block the increase of effects of isoprenaline for swine heart muscle oxygen consumptions on equal molar concentration levels. The results showed also that only the secondary higher concentration of 4 different concentrations of ACC-9089 could block the β-receptor to decrease the heart muscle oxygen consumption in comparison with the control. It was suggested that the highest molar cone. (1.72×10^-3M) of ACC-9089 would probably show an intrinsic sympathomimetic effect which could overlay its blockade effect to β-receptors. That the β-receptor blockers would act as the competitions with isoprenaline to the β-receptors according to their similarity of the side chain chemical structures has been discussed.     

The development of erythropoietic agents in oncology

The erythropoietic agents have achieved a remarkable degree of success as products for the treatment of anaemia associated with cancer chemotherapy. Three agents, epoetin-α, epoetin-β and darbepoetin-α, share this global market and have demonstrated similar efficacy and share similar shortcomings, primarily a lower magnitude of cost/benefit than is the case for the dialysis patient. The continued success of these agents will depend on their ability to address the issue of resistance to therapy in the cancer setting, with the most promising and practical initiatives including cotherapy with parenteral iron, and earlier initiation of therapy. Recently, safety issues have arisen with respect to these agents in the cancer setting, particularly focused on possible promotion of tumour progression. A large body of data suggests that these agents are safe when used in accordance with the package inserts. The data bearing upon these issues will be reviewed and three new agents entering clinical development will be described.