CNS, CSF, and extradural fluid uptake of various hydrophilic materials in the dogfish

Abstract

The distribution of 10 radioactively labeled materials from blood to CSF, extradural fluid (EDF), telencephalon (cerebrum), medulla, and spinal cord was studied in the dogfish shark. Plasma volumes, blood flows, and blood-to-tissue or fluid-transfer half-times (t1/2) were calculated from these distribution data. Blood-EDF exchange occurred at slow but similar rates for all tracers. Urea uptake by the CSF was very rapid compared to that of the other compounds and may be facilitated by a special mechanism. The tissue plasma spaces of all three CNS regions were small (1.1-1.5%). The calculated rates of tissue blood flow (in ml/g-min) were 0.11 for telencephalon and medulla and 0.055 for spinal cord. Choroid plexus blood flow was estimated to be 2.3 ml/g-min, a surprisingly high rate. Transport between blood and tissue was most rapid for water ethylene glycol and slowest for inulin. The tissue t1/2's of urea indicated that a significant portion of this compound's net uptake by periventricaul brain tissue occurred via the CSF.

Unbound Brain-to-Plasma Partition Coefficient, Kp,uu,brain—a Game Changing Parameter for CNS Drug Discovery and Development

“…clarifications (25,124,(144)(145)(146)(147)(148)(149). Kalvass et al (133) discussed that the matter comes down to whether CSF represents the brain interstitium for moderate-to-high permeable compounds without major efflux much better than for compounds with extensive efflux.…”

Measuring diffusion parameters in the brain: comparing the real‐time iontophoretic method and diffusion‐weighted magnetic resonance

“…There are also methods that do not measure the ECS diffusion parameters directly, but which determine a parameter that can be correlated to extracellular volume fraction or tortuosity. These include monitoring the distribution of radioactively labelled material in the tissue (Fenstermacher & Patlak 1977), conductivity measurements (Okada et al. 1994), methods based on light scattering in the tissue (Sykova et al.…”

“…parameter that can be correlated to extracellular volume fraction or tortuosity. These include monitoring the distribution of radioactively labelled material in the tissue (Fenstermacher & Patlak 1977), conductivity measurements (Okada et al 1994), methods based on light scattering in the tissue (Sykova et al 2003) and measurements of the ADC of water using diffusionweighted magnetic resonance (MR) , Sykova 2005a). This last method is the most important because it is non-invasive, provides good spatial resolution and the scanners that can be used for these measurements are widely available.…”

Do the melanophore dispersing hormones pass the cerebrospinal fluid-blood barrier of the killifish, Fundulus heteroclitus?

“…We thank Dr. ItO (Cserr, Fenstermacher, & Rall, 1972;Fenstermacher & Patlack, 1977;Fenstermacher, Patlack, & Blasberg, 1974) and some studies have been made on cyclostomes (Murray, 1975;Murray, Jones, Cserr, & Ball, 1975). In the rat, Greenberg, Whalley, Jourdikian, Mendelson, Walter, Nikolics, Coy, Schally, and Kastin (1976) have shown that labeled peptides injected into the carotid artery penetrate the bloodbrain barrier.…”