Dissimilarities between benzodiazepine-binding sites and adenosine uptake sites in astrocytes and neurons in primary cultures

The question whether the benzodiazepine receptor site in astrocytes or in neurons might be identical to the adenosine uptake site was studied by determining pharmacological profiles, inhibition types, and the effects of benzodiazepine antagonsts in primary cultures of either astrocytes or neurons. Fourteen different benzodiazepines and five different adenosine uptake inhibitors displaced [³H] diazepam and inhibited adenosine uptake in both astrocytes and neurons. However, the rank orders (determined as IC₅₀ values) with which these two parameters were affected were profoundly different, indicating dissimilarities between these two sites. For several of the compounds a difference in inhibition type (competitive vs. noncompetitive) was observed between the benzodiazepine-binding site and the adenosine uptake site in astrocytes and/or neurons, which further corroborated the conclusion of a difference between the benzodiazepine-binding site and the adenosine uptake site. Finally, the neuronal benzodiazepine antagonists RO 15-1788 and CGS-8216 and the astrocytic benzodiazepine antagonist PK 11195, which reverse the action of benzodiazepines, were not able to reverse inhibition of adenosine uptake by diazepam but exerted an inhibitory effect of their own.     

Effect of 5-Aminoisoquinolinone on the Adhesion of Colon Carcinoma

Objective： 5-Aminoisoquinolinone, a water-soluble, potent inhibitor of the activity of poly （adenosine 5＇-diphosphate ribose） polymerase, plays an important role in the tissue injury associated with ischaemia-reperfusion injury and inflammation by inhibiting the activity of poly （adenosine 5＇-diphosphate ribose） polymerase and the expression of cell adhesion molecules such as ICAM-1, P-selectin et al. But how about it in the tumor is not clear. The aim of the present study was to study the effects of 5-Aminoisoquinolinon on the adhesion of colon carcinoma line HT-29 cells to human umbilical vein endothelial cells; and the effects of 5-Aminoisoquinolinon on the expression of ICAM-1, P-selectin and the activity of poly （adenosine 5＇-diphosphate ribose） polymerase in colon carcinoma HT-29 cells. Methods： The adhesion of HT-29 cells to human umbilical vein endothelial cells was detected by adhesive experiment. Immunocytochemically Streptavidin-Peroxidase method was used to investigate the expression of ICAM-1, P-selectin and Poly （adenosine 5＇-diphosphate ribose）（ the product of poly （adenosine 5＇-diphosphate ribose） polymerase activation）. Results： the results of the adhesion assay of HT-29 cells to HUVEC showed that the OD570 value in each 5-AIQ-treated group was significant lower than that in the control group （5-AIQ-untreated） in a dose-dependent manner. The expression of ICAM-1, P-selectin and Poly （adenosine 5＇-diphosphate ribose） was significant lower in 5-Aminoisoquinolinone-treated HT-29 cell group than that in 5-Aminoisoquinolinoneuntreated groups. Conclusion： The data suggest that 5-Aminoisoquinolinone can inhibit the adhesion of HT-29 cells to human umbilical vein endothelial cells. 5-Aminoisoquinolinone also can inhibit poly （adenosine 5＇-diphosphate ribose） polymerase activation and the expressions of ICAM-1 and P-selectin in HT-29 cells. 5-Aminoisoquinolinone probably contributes to the prevention of tumor cell metastasis. Further study is needed.     

去甲肾上腺素缩血管作用对犬冠状血管舒张的限制

在10只麻醉开胸犬的左前降支冠状动脉(LAD)恒流灌注,持续监测灌注压,并于冠脉内注入2.5mg心得宁以阻断心脏的β_1-肾上腺素能受体,观察去甲肾上腺素(NE,α-肾上腺素能刺激)对LAD内给予腺苷所致冠状血管舒张的限制作用。随着LAD内注入的腺苷量增加,冠状动脉阻力(R)咸剂量依赖性降低,分别为对照值的8.7％(2μg/min),20.6％(10μg/min)和28％(50μg/min)。而于LAD内再给予相同齐0量(6μg)的NE,则使不同剂量扩张的冠脉收缩,R成阶梯状增加,分别为对照值的17.4％(腺苷2μg/ml),23.2％(腺苷10μg/min)和34.1％(腺苷50μg/min),表现为隙苷引起的冠状血管扩张愈大,NE能刺激引起的缩血管作用愈强。这表明α-肾上腺素能缩血管作用可限制腺苷引起的冠状血管舒张,因而有助于保持冠状血管张力及其储备力。     

Persistence of Mammary Artery Branches and Blood Supply to the Left Anterior Descending Artery

Background. Partial harvesting of the left internal mammary artery (LIMA) is a widespread technique used during minimally invasive coronary operations performed through a left anterior small thoracotomy. The influence of persisting LIMA branches was investigated to evaluate their effect on the blood flow of the left anterior descending artery.

Methods. Thirty patients, 15 with totally (group A) and 15 with partially (group B) harvested LIMAs, were evaluated. All the patients underwent postoperative angiography, during which a flow map of the LIMA was performed. The average peak velocity and the diastolic-to-systolic peak velocity ratio were recorded. The LIMA graft flow pattern was recorded in the proximal and distal thirds of the artery. Intramammary adenosine (12 to 14 μg) was injected and the average peak velocities before and after injection were calculated.

Results. The average peak velocity was similar in both groups in the proximal and distal thirds of the LIMA (25 ± 7 and 26 ± 5 cm/sec, respectively, in group A versus 27 ± 5 and 25 ± 5 cm/sec, respectively in group B; p = NS). The diastolic-to-systolic peak velocity ratio was similar proximally (0.78 ± 0.3 in group A versus 0.69 ± 0.3 cm/s in group B; p = NS), but not distally (1.72 ± 0.1 in group A versus 0.97 ± 0.3 in group B; p < 0.0005). The LIMA graft flow reserve was similar both proximally and distally (2.6 ± 0.6 and 2.5 ± 0.3 cm/s, respectively, in group A versus 2.6 ± 0.5 and 2.6 ± 0.3 cm/s, respectively, in group B; p = NS).

Conclusions. The persistence of LIMA branches does not influence the blood flow of the left anterior descending artery after acute adenosine-induced myocardial hyperemia. If a left anterior small thoracotomy is used in left anterior descending artery direct revascularization, complete LIMA harvesting is not mandatory and depends on the personal preference of the surgeon.     

钾离子通道的活性状态对蛛网膜下腔注射腺苷抗伤害性作用的影响

目的探讨ATP敏感型钾离子通道的活性状态对鞘内注射腺苷类似物R-phenylisopropyladenosine(R-PIA)抗伤害性作用的影响.方法雄性SD大鼠在苯巴比妥钠麻醉下,蛛网膜下腔留置PE-10导管,测定注药后鼠尾对光热刺激的反应(抗伤害作用).结果蛛网膜下腔注射R-PIA产生剂量依赖性的甩尾时间曲线上移(P＜0.05).蛛网膜下腔注药后10min起效,镇痛时间长达60min.ATP敏感型通道开放剂nicorandil和阻滞剂glibenclamide单独蛛网膜下腔应用无镇痛作用(P＞0.05),但nicorandil明显增强R-PIA的抗伤害性作用,相反glibenclamide明显减弱R-PIA的抗伤害性作用(P＜0.05).结论蛛网膜下腔注射R-PIA可产生明显的剂量依赖性抗伤害作用,此作用受ATP敏感型钾离子通道活性调节.     

A mathematical analysis of kinetic characteristics of oxidative phosphorylation in the animal brain under hypoxic conditions

The kinetic dependence of the rate of oxidative phosphorylation (ADP/t) on the concentration of exogenous ADP has been mathematically analyzed in the brain mitochondria. This relationship has been approximated by a mathematic model under various vital conditions. We propose an analytical approach to calculating the characteristics of oxidative phosphorylation and predicting the kinetics of oxidative ATP synthesis in brain mitochondria of animals subjected to hypoxia.     

Airway hyper-responsiveness to adenosine 5''-monophosphate in preschool-age children with asthma

Airway hyper-responsiveness (AHR) to adenosine 5'-monophosphate (AMP) is closely associated with airway inflammation; however, not all asthmatic patients are responsive to it. This study was planned to investigate the predictive factors of AHR to AMP in asthmatic children aged between 3 and 6 yr. We performed a retrospective analysis of data from 63 asthmatic preschool-age children who were challenged by AMP in our department. All children were characterized by skin-prick tests, serum immunoglobulin E (IgE) levels, peripheral blood eosinophil percentage and bronchial challenge with methacholine (MCH) and AMP. Potential determinants for AHR to AMP were assessed within the group. AHR to AMP was found in 46% of preschool-age children with asthma, while that of MCH was 93.7%. All children responsive to AMP were also responsive to MCH. The geometric mean provocative concentration of MCH and AMP causing a 15% fall in transcutaneous oxygen tension (PC(15)PtcO(2)MCH and AMP) were 0.55 mg/ml (0.004-9.19) and 10.53 mg/ml (0.59-342.89), respectively. AMP-responsive children did not differ from non-responsive ones with respect to demographic factors, geometric mean PC(15)PtcO(2)MCH and atopic status. The median serum IgE level was significantly higher in AMP-responsive group than the non-responsive ones (p = 0.011). The peripheral blood eosinophilia was more frequent among responsive children (p = 0.019), and it was found as the only predictive factor for AMP responsiveness in preschool-age children with asthma in logistic regression model (odds ratio: 5.14; 95% CI: 1.23-21.47; p = 0.025). AMP responsiveness may be predicted by peripheral blood eosinophilia but not with atopy markers in young children with asthma.     

Cytochemical Redistribution of 5'-Nucleotidase in the Developing Cat Visual Cortex

The adenosine-producing ectoenzyme 5'-nucleotidase has recently been shown to undergo a marked redistribution during development of the cat visual cortex and to be involved in the remodelling of ocular dominance columns (Schoen et al., J. Comp. Neurol. , 296 , 379 – 392, 1990). Using an enzyme-cytochemical technique, we now investigate the developmental redistribution of 5'-nucleotidase activity in area 17 of kittens at the ultrastructural level. Between postnatal days 35 and 42, when 5'-nucleotidase is concentrated in layer IV, enzyme reaction product occupies the clefts of asymmetrical synapses within the neuropil. During later development (9th and 13th postnatal weeks), when 5'-nucleotidase spreads over all cortical laminae, the enzyme disappears from its synaptic localization and becomes increasingly associated with astrocytic membranes. The transient appearance of 5'-nucleotidase at synapses parallels the time-course and laminar profile of the synaptic remodelling which takes place during the critical period of visual cortex development. This suggests that synapse-bound 5'-nucleotidase activity plays a role in synaptic malleability, whereas its later association with glial profiles is likely to reflect other functions of the enzyme.     

Characterization of adenosine deaminase (ADA)-negative B-lymphoblastoid cells cocultured with ADA-positive fibroblasts

Abstract: A cell line, BAD05, derived from B lymphocytes of an adenosine deaminase (ADA; EC 3,5,4,4)-deficient patient could not proliferate in a serum-free medium containing 100 μmol/l deoxyadenosine. When BAD05 was cultured with ADA-positive fibroblasts, the proliferation of BAD05 was improved. BAD05 cell density increased when the initially mixed ratio of fibroblasts/BAD05 was 1/10 or higher, but decreased when the ratio was 1/20 or lower. Deoxyadenosine concentrations in the medium and ATP and deoxyATP (dATP) levels in the BAD05 were measured after 4 hours of coculture at initial BAD05 cell densities of 1 × 10⁵and 1 × 10⁶cells/ml. Deoxyadenosine concentrations in the medium decreased as the density of fibroblasts increased. The dATP level decreased as the mixed ratio rose. The ratio of fibroblasts/BAD05 rather than the cell density of fibroblasts had a larger effect on the dATP levels in BAD05. Under our experimental conditions, ADA-negative cells proliferated well when the ratio of ADA-positive cells/ADA-negative cells was over 1/10.