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261.
A novel method for the measurement of the rate of CO2 exchangecaused by solubilization and bicarbonate formation in leavesis presented. The method is based on the measurement of changesin O2 concentration, caused by the uptake or evolution of CO2from the gas flow as a result of solubilization in or desolubilizationfrom leaf tissue, by means of a zirconium-oxide O2 analyser.The advantages of the new method are a fast response and a lackof interference by the CO2 contained in the leaf chamber andleaf intercellular spaces. The method can be used for the investigationof the kinetics of CO2 transport from leaf intercellular spacesto chloroplasts and the role of carbonic anhydrase in this transportand the investigation of mechanistic and ecological aspectsof buffering, proton translocation and other processes controllingpH in chloroplasts of intact leaves. Key words: Leaf, carbon dioxide, pH. 相似文献
262.
We assume that between lateral geniculate and visual cortical cells there exist labile synapses that modify themselves in a new fashion called threshold passive modification and in addition, non-labile synapses that contain permanent information. In the theory which results there is an increase in the specificity of response of a cortical cell when it is exposed to stimuli due to normal patterned visual experience. Non-patterned input, such as might be expected when an animal is dark-reared or raised with eyelids sutured, results in a loss of specificity, with details depending on whether noise to labile and non-labile junctions is correlated. Specificity can sometimes be regained, however, with a return of input due to patterned vision. We propose that this provides a possible explanation of experimental results obtained by Imbert and Buisseret (1975); Blakemore and Van Sluyters (1975); Buisseret and Imbert (1976); and Frégnac and Imbert (1977, 1978).This work was supported in part by a grant from the Ittleson Foundation, Inc. 相似文献
263.
Taurine and synaptic transmission 总被引:1,自引:0,他引:1
264.
Comparison of Two Superfusion Systems for Study of Neurotransmitter Release from Rat Cerebral Cortex Slices 总被引:3,自引:2,他引:1
Depolarization-induced release of [3H]gamma-aminobutyric acid (GABA) and [3H]noradrenaline (NA) from rat cerebral cortex slices was studied in two superfusion systems: one with stationary and the other one with continuously shaken slice compartments. Calcium-dependent depolarization-induced release of GABA and NA could be demonstrated only with shaken slices. GABA, but not NA, could also be released by high K+ media and veratridine from stationary slices. Synaptic transmitter releasing mechanisms are apparently damaged in stationary slices, possibly due to impaired energy metabolism. 相似文献