Brain tissues dimensions

Several factors must be considered when interpreting data from in vivo measurements. The dimensions of the synapse are submicrometer, and, thus, it is unlikely neurotransmitters can be measured directly as synaptic transmission is being carried out with electrodes of micrometer dimensions. Rather, it is likely that measurements that are in vivo will be of those neurotransmitter molecules that have spilled out of the synaptic region. Furthermore, since synapses are often found in close proximity to one another, measurements may well involve secretion from several synapses. Neurotransmitters are actively metabolized by brain tissues, so the probe that is employed must be able to distinguish metabolites from the authentic neurotransmitter as well as other compounds that are found in brain tissue. In addition, the amounts of neurotransmitter in the brain are of quite low levels, as seen from the push-pull and dialysis measurements. Therefore, a technique capable of micromolar concentration measurements is required. 

Fresh mouse heart and liver tissues were pre-cut into thin slices using carbon steel surgical blades with at least one dimension at less than 2 mm. Fresh mouse brain was used directly without pre-cutting. All tissue or thin tissue slices were snap frozen in liquid N2 immediately and stored in -80°C prior to usage see Note 3). 

For a typical mouse brain section of dimensions 16 p,m thickness with a surface of lOx 5 mm, the tissue volume... 

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