Cerebrospinal fluid production rate

Curran, R.E., et al.. Cerebrospinal fluid production rates determined by simultaneous albumin and inulin perfusion. Experimental Neurology, 1970. 29, 546-553. 

The choroid plexus are bags composed of epithelial cells that project into the ventricles and contain a capillary plexus (lohanson, 1988). The capillaries do not have barrier function and so produce an ultrafiltrate, w hich fills the bag. The epithelial cells have tight junctions and so prevent the ultrafiltrate fi om entering the ventricular space. Unlike the capillaries, the epithelial cells of the choroid plexus have a high rate of vesicular turnover, w hich is responsible for the production of the cerebrospinal fluid (CSF). How ever, the CSF is not an ultra-filfi ate, but a secreted substance. The choroid plexus also has many selective transport systems, some of w hich are specific to it or are enriched in comparison to the vascular BBB. 

An especially important case is that of the brain. We may, as a rough model of the human body, consider two reservoirs of fluid, the blood and lymph, with volume Fj, and cerebrospinal fluid, the extracellular fluid of the brain and spinal column, with volume Fj. We assume that a vital substance is destroyed in each of these reservoirs at a characteristic rate, corresponding to the rate constants k- and k, that it diffuses across the blood-brain barrier at a rate determined by the product of the permeability and area of the barrier and the difference of the concentrations in the two... 

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