Quantification of efflux into the blood and brain of intraventricularly perfused [3H]thymidine in the anaesthetized rabbit

Abstract

SUMMARYStudies using choroid plexuses incubated in vitro have led to the conclusion that pyrimidine deoxyribonucleosides, such as thymidine, enter the brain predominantly through the blood-cerebrospinal fluid (CSF) barrier across the choroid plexuses. In order to examine this hypothesis, ventriculocisternal perfusions were carried out to determine the magnitude of the passage of [3H]thymidine from the CSF into the brain and blood. These experiments demonstrated that approximately 50 % of the [3H]thymidine was eliminated from the CSF perfusate, some 41 6 + 5 6 % passing into the blood and only 7.6 + 0 6 % to the brain. Efflux into both the blood and brain was saturable, with a Km of 17 8 /tM and a Vmax of 047 nm min-1, and partially nitrobenzylthioinosine (NBMPR) sensitive. However, a non-saturable component did exist (Kd,tl min-'). Overall, the rapid removal of [3H]thymidine from the CSF and its low uptake from the CSF into the brain suggests that the choroid plexuses would be an inefficient pathway for the entry of this pyrimidine deoxyribonucleoside into the brain.

Cerebrospinal fluid may mediate CNS ischemic injury

“…Although depletion of the CSF does not eliminate ISF, it limits the extent to which the ISF can be replenished from the CSF and limits occurrence of edema. It is estimated that the total volume of CSF is about 2.3 ml or 0.67 ml/kg for an adult rabbit, and the CSF production rate is reportedly to be between 7.8–8.8 μl/minute [16-18]. We were only able to remove 0.8–1.2 ml CSF.…”

Postnatal Phencyclidine Administration Selectively Reduces Adult Cortical Parvalbumin-Containing Interneurons

“…or i.v. administration BrdU is transported across the bloodbrain barrier by the thymidine nucleoside transporter (Lynch et al, 1977) and is metabolized rapidly through dehalogenation with a half-life of approximately 10 min (Kriss et al, 1963) and may also be eliminated through the cerebrospinal fluid (Thomas née Williams and Segal, 1996;Thomas et al, 1997;Spector and Berlinger, 1982). The S phase of a cell cycle is about 6-7 h and a cell cycle has been estimated at 12-14 h (Hayes and Nowakowski, 2002) as the S phase commonly comprises a third to half of the cell cycle (Alexiades and Cepko, 1996;Bhide, 1996;Takahashi et al, 1995).…”

Metabolic mechanisms of development and compensation of osmotic stress in the brain

“…Экстравазация альбумина после повреждения гематоэнцефалического барьера повышает коллоидное осмотическое (син. онкотическое) давление в интерстициальной жидкости, что вытягивает воду из капилляров и приводит к вазогенному отеку [8,9].…”