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排序方式: 共有1425条查询结果,搜索用时 15 毫秒
1.
《Bioorganic & medicinal chemistry letters》2014,24(1):382-385
The chiral isomers of the two potent simplified RTX-based vanilloids, compounds 2 and 3, were synthesized employing highly enantioselective PTC alkylation and evaluated as hTRPV1 ligands. The analysis indicated that the R-isomer was the eutomer in binding affinity and functional activity. The agonism of compound 2R was comparable to that of RTX. Docking analysis of the chiral isomers of 3 suggested the basis for its stereospecific activity and the binding mode of 3R. 相似文献
2.
Stimulatory Effect of the D2 Antagonist Sulpiride on Glucose Utilization in Dopaminergic Regions of Rat Brain 总被引:1,自引:0,他引:1
Gilberto Pizzolato Timothy T. Soncrant Denise M. Larson Stanley I. Rapoport 《Journal of neurochemistry》1987,49(2):631-638
Local cerebral glucose utilization (LCGU) was measured, using the quantitative autoradiographic [14C]2-deoxy-D-glucose method, in 56 brain regions of 3-month-old, awake Fischer-344 rats, after intraperitoneal administration of sulpiride (SULP) 100 mg/kg. SULP, an "atypical" neuroleptic, is a selective antagonist of D2 dopamine receptors. LCGU was reduced in a few nondopaminergic regions at 1 h after drug administration. Thereafter, SULP progressively elevated LCGU in many other regions. At 3 h, LCGU was elevated in 23% of the regions examined, most of which are related to the CNS dopaminergic system (caudate-putamen, nucleus accumbens, olfactory tubercle, lateral habenula, median eminence, paraventricular hypothalamic nucleus). Increases of LCGU were observed also in the suprachiasmatic nucleus, lateral geniculate, and inferior olive. These effects of SULP on LCGU differ from the effects of the "typical" neuroleptic haloperidol, which produces widespread decreases in LCGU in the rat brain. Selective actions on different subpopulations of dopamine receptors may explain the different effects of the two neuroleptics on brain metabolism, which correspond to their different clinical and behavioral actions. 相似文献
3.
Body wall organization in enchytraeids 总被引:2,自引:2,他引:0
Roberto Valvassori Magda de Eguileor Giulio Lanzavecchia Giorgio Scari 《Hydrobiologia》1989,180(1):83-89
The muscle organization of the body wall in some species of oligochaetes belonging to the Enchytraeus genus is described. No differences have been detected in their circular muscles, whereas longitudinal muscles show significant differences, allowing an easy identification of the various worm species. In particular, differences are noticeable in the external longitudinal layer. These observations suggest that structural and ultrastructural muscle fiber organizations can be used as a taxonomic tool. 相似文献
4.
J. M. Ramirez K. G. Pearson 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(4):475-483
1. The effect of phentolamine on the response properties of insect mechanoreceptors and on the conduction in their axons was examined using electrophysiological techniques. 2. Phentolamine blocked conduction of action potentials along axons, an effect which exhibited 3 characteristics typical of local anesthetics: the effect was frequency-dependent, reversible and varied for nerves with different diameters. 3. The concentration of phentolamine required to block axonal conduction (1-2 x 10(-3) M) was significantly higher than that required to abolish the response of receptors to mechanical stimulation (3-5 x 10(-4) M). 4. All mechanoreceptors that were examined in Locusta migratoria and Periplaneta americana were inactivated by phentolamine (Table 1). The type I receptors (chordotonal, campaniform and hair sensilla) were inactivated within 5-15 min following phentolamine application. The only type II receptor examined (forewing stretch-receptor) underwent a phase of repetitive discharge before being inactivated. 5. Tolazoline and metoclopramide inactivated, like phentolamine, mechanoreceptors at lower concentrations than necessary to block axonal conduction. However, yohimbine and chlorpromazine inactivated mechanoreceptors and blocked axonal conduction at similar concentrations. 6. These findings suggest that phentolamine affects sense-organ specific ionic processes that are more sensitive to the drug than the ionic processes along the axons. 相似文献
5.
Tatsumi Nagahama Mitsuru Takata 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(1):1-10
1. | Spikes in Aplysia MA1 neurons produced excitatory (EJPs), inhibitory (IJPs), and diphasic inhibitory-excitatory junction potentials in different fibers of the buccal muscles. |
2. | The IJPs following the MA1 spikes were recorded in the muscle fibers innervated by the jaw-closing motoneurons. The depolarization of muscle fibers produced by the motoneurons was largely suppressed by simultaneous MA1 firing, suggesting that the MA1 neurons make a direct connection to a part of the muscle fibers innervated by these motoneurons and inhibit them. |
3. | The excitatory and inhibitory components of the junction potentials produced by MA1 were reversibly blocked by hexamethonium and d-tubocurarine, respectively. In contrast, the EJPs produced by the jaw-closing motoneurons were blocked by an amino acid antagonist, suggesting that the MA1 neurons and the jaw-closing motoneurons use different transmitters in the nerve-muscle junctions. |
4. | The jaw movement produced by the jaw-closing motoneurons was suppressed by simultaneous MA1 firing, and the suppression was released by d-tubocurarine, suggesting that the IJPs produced by MA1 may contribute to the suppression of jaw movement. The firing of MA1 produced the vertical movement of the buccal muscles, which was blocked by hexamethonium, suggesting that the EJPs produced by MA1 may contribute to the vertical movement. |
6.
Masayuki Nishida Hirotaka Nishijima Kazuya Yonezawa Isao Sato Teisuke Anzai Kohichi Okita Hisakazu Yasuda 《European journal of applied physiology and occupational physiology》1992,64(6):528-533
To assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J.cm-2 CSAmax for 1 min and an increment of 1 J.cm-2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of 31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2, P less than 0.05]. The absolute maximal exercise intensity (J.min-1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J.min-1.cm-2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5'-diphosphate to drive adenosine 5'-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J.min-1.cm-2).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
Darryl J. Lee Maria J. Stokes Robert J. Taylor Robert G. Cooper 《European journal of applied physiology and occupational physiology》1992,64(3):199-203
In 31 normal subjects (17 male), aged 19-48 years, and 8 patients with chronic low back pain (4 male), aged 37-55 years, the repeatability of surface recordings of acoustic myography (AMG) and electromyography (EMG) were examined in the lumbar paraspinal muscles. Five isometric test positions were examined. In 21 of the normal subjects, four positions tested were: quiet standing, half extension from prone lying, full extension from prone with and without resistance. In 10 of the normal subjects and the 8 back pain patients, a standardised, unsupported horizontal position with the upper body over the end of a couch was tested. The AMG and EMG signals were full-wave rectified and integrated (iAMG and iEMG). The variability of recordings during repeated 5-s isometric contractions was assessed by analysis of variance (ANOVA) and the coefficient of variation (CV) was calculated from the ANOVA. Both recording techniques produced the most repeatable results during the unsupported, horizontal hold position. In the normal subjects, CV were, iAMG 5.6%, iEMG 4.9%; and in the patients, iAMG 4.4%, iEMG 2.6%. The CV for the other four isometric test positions ranged from 15.3% to 29.4% for iAMG, and 8% to 15.7% for iEMG. These results demonstrated that a controlled test manoeuvre for examining AMG and EMG of the paraspinal muscles was vital for repeatable recordings. The CV for the standardised, horizontal position were lower than for previously published results.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
8.
下丘脑室旁核加压素能神经元参与电针刺激对实验性内脏痛的抑制 总被引:1,自引:0,他引:1
本实验采用内脏痛的实验模型,探讨室旁核中的加压素在针刺抑制内脏痛中的作用。实验结果如下:(1)大鼠在在射酒石酸锑钾(0.1%,10ml/kg,i.p.)后,出现可定量的扭体反应,能作为观察内脏痛的客观指标。(2)电针对内脏痛有抑制效应,即具有镇痛作用。(3)电刺激室旁核,能加强电针对内脏痛的抑制效应,损毁室旁核,则此抑制效应基本消失。(4)脑室注射加压素抗血清(14μl)或加压素拮抗剂[d(CH_2)_5Tyr(Me)-AVP,500ng/5μl]都能明显减弱电针的抑制效应。(5)腹腔注射加压素拮抗剂(10μg/kg),不能翻转电针的抑制效应。上述实验结果表明,下丘脑室旁核的加压素能神经元参与了电针刺激对实验性内脏痛的抑制。 相似文献
9.
G Zhu L H Wu C Mauzy A M Egloff T Mirzadegan F Z Chung 《Journal of cellular biochemistry》1992,50(2):159-164
A conserved aspartic acid residue in the third transmembrane region of many of the G protein-coupled receptors has been shown to play a role in ligand binding. In the case of endothelin receptors, however, a lysine residue replaces this conserved aspartic acid residue. To access the importance of this residue in ligand binding, we have replaced it with an aspartic acid in the rat endothelin type B (ETb) receptor by PCR mediated mutagenesis. The binding characteristics and functional properties of both the wild type and mutant receptors were determined in COS-7 cells transiently expressing the cloned receptor cDNAs. Using 125I-ET-1 as the radioactive peptide ligand in displacement binding studies, the wild type receptor displayed a typical non-isopeptide-selective binding profile with similar IC50 values (0.2-0.6 nM) for all three endothelin peptides (ET-1, ET-2, and ET-3) and sarafotoxin 6c (SRTX 6c). Interestingly, the mutant receptor showed an increase in IC50 values for ET-1 (5 nM), ET-2 (27 nM), and ET-3 (127 nM) but displayed a much larger increase in IC50 value for SRTX 6c (> 10 uM). The lysine mutant receptor still elicited full inositol phosphate (IP) turnover responses in the presence of saturating concentrations of endothelins (10 nM of ET-1, 100 nM of ET-2, or 1 uM of ET-3), indicating that the mutation (K181D) did not affect the coupling of mutant receptor to the appropriate G protein. These results demonstrate that lysine-181 on the receptor is important for binding ET peptides; however, it is required for binding the ETb selective agonist-SRTX 6c. 相似文献
10.
The relative appearance of the parietal muscles in the development of the zooids has been studied in several ctenostomatous and “cheilostomatous” species. A comparison of the different on-togenetical sequences demonstrated that a “cheilostomatous” type of organization of the zooids with a great probability has been achieved in minimum three times independentl and originated from different ctenostomatous sub-grous: the Membranidea from plesiomorgic victorelloids (ancestors of Bulbella with not yet developed peristomial tube), the Inoviceiata (Aetea) from advanced forms of victorelloids with reduced primary parietal muscles (perhaps stcies related to Pottsiella), and Penetrantia from arachnidioid or vesicularioid ancestors (?). Therefore, the classical orders α“Ctenostomata” and “Cheilostomata” represent only “stage groups” but no monohyletic systematical units. Because of the new concept and interpretation I propose a new name for the united group: Cteno-Cheilostomata, supra-ord. nov. 相似文献