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91.
Zusammenfassung 200 g schwere Ratten erhielten Lösungen von14C-Coffein entweder nüchtern oder nach vorheriger Verabreichung von Kohlenhydrat, Eiweiß und Fett. Die Nahrungszufuhr bedingte folgende Änderungen der Coffeinverteilung im Organismus gegenüber den nüchternen Tieren: die Coffeinresorption war deutlich verzögert, so daß die14C-Aktivitätswerte im Serum und Carcass nur langsam anstiegen. Im weiteren Verlauf des Versuches erreichte der Abfall der14C-Aktivität in Serum und Carcass und ihre Ausscheidung im Harn ein geringeres Ausmaß.Die Coffeinverteilung im Organismus zeigte außerdem bestimmte Änderungen bei Ratten, die im Anschluß an eine 14tägige Gewöhnunsperiode14C-Coffeinhaltigen Kaffee-Infus erhielten. Im Vergleich zu den nicht an Kaffee gewöhnten Ratten war hierbei die Coffeinresorption deutlich beschleunigt. Die14C-Aktivitätswerte im Serum stiegen anfangs schneller und höher an, zeigten anschließend aber einen rascheren Abfall. Auf Grund dieser Effekte war die14C-Ausscheidung durch die Niere erheblich beschleunigt und vermehrt.
Summary Rats weighing 200 g obtained14C-caffeine solution either after starvation or after feeding carbohydrate, proteine or fat. The following differences in caffeine distribution in the fed rats compared with the starved ones were confirmed: caffeine absorption was clearly decreased, resulting in slow increase in14C-activity in the serum and the carcass. During the course of the experiment it was observed that the decline of14C-activity in serum and carcass was delayed and its excretion in the urine was decreased. Additionally caffeine distribution in the rat body showed certain changes which were accompanied by caffeine habituation in the animals after administration of14C-caffeine contained in coffee infusion for 14 days. In the coffee habituated animals the caffeine absorption was noticeably accelerated.14C-activity in serum increased initially quicker but finally showed a quicker decline. Governed by these effects the14C-excretion via kidney was increased and its rate was accelerated.
  相似文献   
92.
Cerebellar damage impairs automaticity of a recently practiced movement   总被引:7,自引:0,他引:7  
It has been suggested that the cerebellum plays a critical role in learning to make movements more "automatic" (i.e., requiring less attention to the details of a movement). We hypothesized that cerebellar damage compromises learning of movement automaticity, resulting in increased attentional demands for movement control. The purpose of our study was to determine whether cerebellar damage disrupts the ability to make a practiced movement more automatic. We developed a dual task paradigm using two tasks that did not have overlapping sensory or motor requirements for execution. Our motor task required subjects to maintain an upright posture while performing a figure-8 movement using their arm. This motor task was chosen to simulate requirements of everyday movements (e.g., standing while reaching for objects), but it was novel enough to require practice for improvement. Our secondary task was an auditory vigilance task where subjects listened to letter sequences and were asked to identify the number of times a target letter was heard. We tested controls and people with cerebellar damage as they practiced the movement task alone and then performed it with the auditory task. We recorded 3D position data from the arm, trunk, and leg during the movement task. Errors were recorded for both the movement and the letter tasks. Our results show that cerebellar subjects can improve the movement to a very limited extent with practice. Unlike controls, the motor performance of cerebellar subjects deteriorates to prepractice levels when attention is focused away from the movement during dual task trials. Control subjects' insensitivity to dual task interference after practice was due to learned movement automaticity and was not a reflection of better dual task performance generally. Overall, our findings suggest that the cerebellum may be important for shifting movement performance from an attentionally demanding (unpracticed) state to a more automatic (practiced) state.  相似文献   
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94.
Localization of corticotropin-releasing activity in the rat hypothalamus   总被引:1,自引:0,他引:1  
Hypothalamic nuclei were removed from frozen sections of rat brain and examined for their corticotropin-releasing activity. The highest concentration was measured in the median eminence. In addition there was significantly more activity detected in the nuclei paraventricularis, supraopticus, suprachiasmaticus and arcuatus than in the other nuclei.  相似文献   
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97.
ATP activates K+ channels by increasing intracellular calcium activity in Madin Darby canine kidney (MDCK) cells. The present study has been performed to test for the involvement of G-proteins and of protein kinase C in the intracellular transmission of these effects. To this end, the effect of ATP on intracellular calcium and K+ channel activity has been studied in cells pretreated with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) and/or pertussis toxin. The ATP-induced increase of intracellular calcium is not significantly affected by pretreatment with pertussis toxin, is significantly blunted by pretreatment with TPA and is abolished by pretreatment with both pertussis toxin and the phorbol ester. The ATP activation of K+ channels is similarly blunted by pretreatment with TPA, but is not abolished by pretreatment with both the phorbol ester and pertussis toxin. Furthermore, the ATP-induced hyperpolarization is not abolished in cells pretreated with both pertussis toxin and TPA. In those cells, ATP may activate K+ channels by calcium-independent mechanisms or lead to localized increases of intracellular calcium sufficient to activate the K+ channels but escaping detection with fura-2 fluorescence.  相似文献   
98.
根据Wiederhielm的阻抗平衡压力检测原理,设计了一个改进的伺服零微血管测压系统。利用该系统检测了蟾蜍及蛙肠系膜内微小动脉的压力、获得了各管径级的压力和脉压的参数,并观察了药物的作用,探讨了微动脉内压力的波动特性以及应激情况下压力的骤变式与脉动式的交替,为微循环研究提供一些有价值的现象。  相似文献   
99.
目的:研究并比较结核分枝杆菌免疫保护性抗原DNA(Ag85A和ESAT-6)疫苗联合免疫,BCG免疫以及联合DNA疫苗初免-BCG加强免疫等不同的免疫策略,诱导免疫应答效果观察.方法:健康雌性BALB/c小鼠24只,随机分成PBS 阴性对照组,DNA初免-BCG异源加强组,DNA(Ag85A和ESAT-6)初免DNA同源加强组和BCG阳性对照组,共进行3次免疫,初免2次,最后1次加强,间隔2周1次.PBS组3次均注射PBS 溶液;DNA/BCG组以质粒DNA免疫2次,最后1次以BCG加强免疫;DNA/DNA组3次均以质粒DNA进行免疫;BCG组则注射PBS溶液2次后以BCG免疫.末次免疫后4、6、8周分别分离血清测定总IgG水平,同时分离小鼠脾细胞,体外经TB-PPD刺激后进行淋巴细胞增殖实验(XTT法)并测定脾细胞培养上清中IFN-γ和IL-4水平.结果:DNA/BCG、DNA/DNA、BCG组体外经TB-PPD刺激后均检测到特异性IgG抗体产生,3组平均效价为1:120、1:160、1:80,DNA/DNA组的抗体效价高于另外2组;小鼠脾细胞体外经TB-PPD刺激后,均能产生特异性淋巴细胞增殖并诱生较强的IFN-γ反应,其中DNA/BCG组IFN-γ的分泌水平高于DNA/DNA组和BCG组(P<0.05).结论:联合DNA疫苗初免-BCG加强的免疫策略能在小鼠体内诱导较强的特异性细胞免疫反应,产生高水平的IFN-γ.  相似文献   
100.
NGF在成年猴脑的分布   总被引:1,自引:1,他引:1  
为了解NGF在成年猴脑的分布,采用免疫组化SP法对成年猴脑多个冠状位切片进行免疫组化反应。结果证明,NGF阳性反应神经元主要分布于大脑皮质Ⅲ、V层,小脑Purkinje细胞,海马,齿状回,纹状体,脑干网状结构等处。此外,在黑质、舌下神经核、迷走神经背核、前庭神经核、三叉神经核、疑核、下橄榄核也出现NGF阳性反应。在大脑和脑干还观察到NGF阳性胶质细胞。本实验结果表明,在成年猴脑的多个脑区有NGF表达,提示NGF可能涉及猴脑某些神经元及胶质细胞的生理过程。  相似文献   
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