engleski

Effect of body activity and active transport on concentration gradients of 5-hydroxyidoleacetic acid in the cerebrospinal fluid

Abstract Effect of body activity and active transport on concentration gradients of 5-hydroxyindoleacetic acid in the cerebrospinal fluid Background and purpose: 5-hydroxyindoleacetic acid (5-HIAA) shows different concentrations in various compatrments of cerebrospinal fluid (CSF), which cannot be annulled by the blockade of active transport of 5-HIAA by probenecid in imobile, anesthetized dogs. The question arises whether these concentration gradients of 5-HIAA can be canceled in free moving dogs by enhanced mixing of CSF. Material and methods: Five hours after application of probenecid in free moving dogs samples of CSF for analysis of 5-HIAA were taken during short thiopenton anestesia. In control group of free moving dogs the CSF was sampled in the same way. Results: In control dogs the concentration of 5-HIAA in CSF of cisterna magna was significantly lower than in ventricular and cortical CSF but higher than in lumbar CSF, while in probenecid treated dogs these 5-HIAA gradients disapeared. Conclusion: Active transport sustains gradients of 5-HIAA in CSF while body activity by enhancement of mixing of CSF has the opposite tendency, i.e. cancellation of these gradients. This speaks against the classical hypothesis of CSF circulation and absorption and removal of metabolites across arachnoid villi, and supports our view that substances are removed across cerebral capillaries.

5-hydroxyindoleacetic acid; cerebrospinal fluid (CSF); gradients; active transport; mixing of CSF; body activity

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