The Penetration of Carbon-14 Urea into Cerebrospinal Fluid and Various Areas of the Cat Brain

A Systems Analysis of Cerebral Dehydration

“…The value of K4 was obtained by methods to be discussed below. The responses shown in Figure 12 are very similar to those presented by Schoolar et al (20) and to those measured in our laboratory. These curves were not greatly affected by adjustments in the reflection coefficients and hydraulic conductivities.…”

“…899). Evidence for this pathway is provided by Schooler et al (20) who showed that in response to a pulse input of C 14 urea, the BTW urea concentration rose to a higher value than the CSF and also led the response in the CSF. Bradbury and Davson (30) discuss this pathway in detail and demonstrate that urea transport through the "blood brain barrier" is by simple, non-mediated, reversible diffusion.…”

Mechanisms of Drug Absorption and Excretion Passage of Drugs in and out of the Central Nervous System

“…Control data were presented only for salicylate and therefore comparison was ren dered difficult. The controls presented in Table II are derived from previous publications (61,62,63). Salicylate and phenobarbital showed consistently higher brain:plasma ratios after hypercapnia and lower ratios after hypo capnia.…”

Effect of hypertonic urea on cerebrospinal fluid pressure and brain volume

“…Gilboe, Javid & Frechette (1960) found that less than 1 % of the radioactivity injected as 14C urea could be recovered as C02 within 24 hr. Schoolar, Barlow & Roth (1960) chromatographed tissues from animals injected with radioactive urea and reported that all radioactivity was in a band comparable to a known 14C-urea band. To establish that the radioactivity administered as urea in these experiments remained as urea, samples of c.s.f., brain, and plasma were subjected to paper electrophoresis.…”