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1. Exchange of (3)H(2)O with H(2)O takes place rapidly in incubated rat brain slices but at a lower rate in slices from infant brain than from adult brain. The temperature coefficient (Q(10)) of the exchange process, between 37 and 4 degrees C, is 1.76 with infant brain and 1.26 with adult brain. The exchange process is unaffected by the presence of ouabain or 2,4-dinitrophenol. 2. An approximately linear relationship exists between water uptake and the concentration of ATP in the incubated slices in the presence of various concentrations of glucose. Little or no change occurs in water uptake and ATP concentration in the presence of a glucose concentration exceeding 3mm. A linear relationship also exists between the water uptake and ATP concentration in the presence of 10mm-glucose and various concentrations of sodium l-glutamate but the line is parallel to that found with changed glucose concentrations and shifted in the direction of increased water uptake. A similar parallel relationship exists between water uptake and ATP concentration in the presence of 2,4-dinitrophenol, but the amount of water uptake is significantly smaller in the presence of 2,4-dinitrophenol than in its absence. 3. Copper chloride (0.3mm) or mercuric chloride (0.3mm) both increase water uptake and diminish the ATP concentration in slices. Sodium malonate (2mm) or sodium d-glutamate (10mm) has similar effects. 4. Substances, or conditions, affecting water uptake in incubated brain slices may be divided roughly into two classes in accordance with their effects on adenosine triphosphatase and membrane permeability, but there may be considerable lack of specificity.  相似文献   

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After incubation of rat brain homogenates with S-adenosyl-L-homocysteine (10 microM), norepinephrine uptake was modified according to the norepinephrine concentration. For low-range concentrations, uptake was lowered, whereas for high-range concentrations, uptake was increased.  相似文献   

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Effect of atropine on the uptake of labeled carbachol by rat brain slices   总被引:1,自引:0,他引:1  
R Creese  D B Taylor 《Life sciences》1965,4(16):1545-1547
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A crude preparation of neurotransmitter storage vesicles was obtained by differential centrifugation and the ability to take up 3H-dopamine was evaluated invitro. The uptake was highly dependent on temperature, had an absolute requirement for ATP and Mg2+ and was inhibited totally by reserpine. The uptake displayed saturation kinetics, with a Km of 0.26 μM at 20°. 3H-dopamine uptake was inhibited competitively by norepinephrine, with a Ki of 0.69 μM. Vesicles derived from a primarily dopaminergic region (corpus striatum) exhibited the same ratio of uptakes of 3H-dopamine/3H-norepinephrine as did those from a primarily noradrenergic region (cerebral cortex). These results indicate that viable rat brain storage vesicles can be readily prepared and used for evaluation of pharmacologic effects on 3H-dopamine uptake, and that dopaminergic and noradrenergic storage vesicles exhibit identical uptake properties.  相似文献   

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Previous studies suggest that developing rat brain is susceptible to reduced thiamine intake. In order to assess the metabolic basis for this susceptibility, activities of three thiamine-dependent enzymes (pyruvate dehydrogenase complex, -ketoglutarate dehydrogenase and transketolase) were measured in homogenates of brain tissue from the offspring of thiamine-deficient mothers. Control groups of animals were pair-fed to equal food consumption with the thiamine-deficient animals. The study revealed region-selective delays in the establishment of adult activities of thiamine-dependent enzymes as a result of maternal thiamine deficiency. Pyruvate dehydrogenase complex activities in cerebral cortex were significantly reduced (by 20% P < 0.05); -ketoglutarate dehydrogenase activities were also reduced in cerebral cortex (by 30% P < 0.05). In the case of transketolase, enzyme activities were significantly reduced in cerebral cortex, cerebellum and brainstem. Following thiamine replenishment, defective enzyme activities were restored to normal in all cases. However, since thiamine-dependent enzymes are important for the establishment of adult patterns of cerebral energy metabolism and also in myelin synthesis, maternal thiamine deficiency resulting in reductions of thiamine-dependent enzymes at a vulnerable period in brain development could have serious metabolic consequences leading to permanent neurological sequellae in the offspring.  相似文献   

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A study of the fluid uptake of rat kidney slices in vitro   总被引:5,自引:3,他引:5       下载免费PDF全文
Rat renal cortical and medullary tissues show a marked elevation of relative water content when immersed in "physiological solutions" containing sodium and chloride ions, or in equally concentrated solutions of monosaccharides. In contrast to this, no increase in relative water content occurs in isosmotic solutions of three disaccharides studied. It appears to be unlikely that the fluid uptake is a result of intracellular hypertonicity existing either physiologically or pathologically. A more satisfactory alternative hypothesis is that ingress of water accompanies entrance of solutes (ions, monosaccharide molecules) into the tissue cells.  相似文献   

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