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THE ORIGIN OF THE ACETYLCHOLINE RELEASED FROM THE SURFACE OF THE CORTEX   总被引:4,自引:2,他引:2  
—The specific radioactivity of acetylcholine liberated from the surface of the rabbit occipital cortex has been compared with that of the underlying cortical synaptosomal and vesicular acetylcholine at varying times after the administration of [N-Me-3H]choline. Choline was administered by diffusion from solutions placed in cups formed by Perspex cylinders applied to the surface of the cortex. Acetylcholine was collected by diffusion into these cups. The specific radioactivity of the acetylcholine declined progressively. The effect of stimulation of afferent cholinergic pathways was to cause a fall in the specific radioactivity of the released acetylcholine. However this was always higher than that of the synaptosomal or vesicular acetylcholine as represented by fractions P2 and D of the authors’fractionation scheme. It is concluded that acetylcholine released from the cortex must come from a store or stores more recently synthesized than the endogenous acetylcholine of these subcellular fractions.  相似文献   

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太湖贡湖湾食物网特征研究   总被引:1,自引:0,他引:1  
应用稳定性同位素技术(13C和15N)研究了太湖贡湖湾食物网特征, 结果显示由于食物来源变化多样性影响, 导致贡湖的食物网结构和营养级关系变化较为复杂, 贡湖主要生物类群13C、15N值表现出较大的种间差异。消费者13C值从摇蚊幼虫的-32.3到锯齿米虾的-22.1, 其值大小与营养级的关系没有规律性。消费者平均15N值从褶纹冠蚌的10.3到位于顶端间下鳙的19.0, 随营养级位置而升高。群落中所有种类的15N、13C值之间没有相关性(r=0.1835, P0.05), 表明该食物网是非线性食物网。研究结果验证了杂食性生物有机体普遍存在于富营养化的贡湖水域生态系统中, 且13C结果表明, 浮游植物、固着藻类以及沉水植物为贡湖食物网中大多数生物有机体的主要碳源。贡湖食物链长度为4.44营养级。  相似文献   

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Tumors of the adrenal glands produce hormones which cause a variety of symptoms and signs including high blood pressure, excessive growth of hair on the body and precocious sexual development. By recently developed tests, it has been possible to differentiate high blood pressure due to these tumors from hypertension due to other causes. Removal of these tumors will often alleviate changes caused by them. Localization of the tumor and appraisal of the condition of the contralateral gland should be carried out preoperatively if possible. In this, several kinds of roentgen studies are helpful. Infusions of drugs during operation can be used to control the blood pressure which otherwise would vary widely. During a ten-year period (1942 to 1951) there were observed at the Los Angeles County General Hospital 100 proved cases of non-secreting and secreting primary neoplasms of the adrenal glands. In addition, there were three cases of Cushing's syndrome due to bilateral adrenal cortical hyperplasia, and ten probable cases (four, pheochromocytomas; five, Cushing's syndrome; one, adrenogenital syndrome) in which operation was not done.  相似文献   

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