Blood—Brain Barrier Transport of Butanol and Water Relative to N-Isopropyl-p-Iodoamphetamine as the Internal Reference
- 1 June 1985
- journal article
- research article
- Published by SAGE Publications in Journal of Cerebral Blood Flow & Metabolism
- Vol. 5 (2), 275-281
- https://doi.org/10.1038/jcbfm.1985.35
Abstract
The literature regarding the blood–brain barrier (BBB) transport of butanol is conflicting as studies report both incomplete and complete extraction of butanol by the brain. In this work the BBB transport of both [14C]butanol and [3H]water was studied using the carotid injection technique in conscious and in ketamine- or pentobarbital-anesthetized rats employing N-isopropyl- p-[125I]iodoamphetamine ([125I]IMP) as the internal reference and as a fluid microsphere. The three isotopes (3H, 125I, 14C) were conveniently counted simultaneously in a liquid scintillation spectrometer. IMP is essentially completely sequestered by the brain for at least 1 min in conscious rats and for 2 min in anesthetized animals. Butanol extraction by rat forebrain is not flow limited but ranges between 77 ± 1 and 87 ± 1% for the three conditions. The incomplete extraction of butanol by the forebrain is due to diffusion restriction of butanol clearance in some regions (frontal cortex, colliculi) but not in others (caudate, hippocampus, olfactory bulb). The permeability-surface area product/cerebral blood flow ratio of butanol and water in rat forebrain remains relatively constant, 1.7 ± 0.2 and 1.0 ± 0.1, respectively, despite a twofold increase in cerebral blood flow in conscious relative to pentobarbital-anesthetized rats. The absence of an inverse relationship between flow and butanol or water extraction is consistent with capillary recruitment being the principal mechanism underlying changes in cerebral blood flow in anesthesia. The diffusion restriction of BBB transport of butanol in some regions, but not in others, necessitates a careful regional analysis of BBB permeability to butanol prior to usage of this compound as a cerebral blood flow marker.Keywords
This publication has 18 references indexed in Scilit:
- Quantitative regional determination of morphometric indices of the total and perfused capillary network in the rat brain.Circulation Research, 1982
- Evaluation of [123I]Isopropyliodoamphetamine as a Tracer for Local Cerebral Blood Flow Using Direct Autoradiographic ComparisonJournal of Cerebral Blood Flow & Metabolism, 1982
- Comparison of radio-labeled butanol and iodoantipyrine as cerebral blood flow markersBrain Research, 1981
- Cerebral extraction of N-13 ammonia: its dependence on cerebral blood flow and capillary permeability -- surface area product.Stroke, 1981
- Rapid simultaneous determination of regional blood flow and blood‐brain glucose transfer in brain of rat1Acta Physiologica Scandinavica, 1980
- Regional blood‐brain barrier transport of the steroid hormonesJournal of Neurochemistry, 1979
- Blood-brain barrier permeability of 11C-labeled alcohols and 15O-labeled waterAmerican Journal of Physiology-Legacy Content, 1976
- Analysis of brain uptake and loss or radiotracers after intracarotid injectionAmerican Journal of Physiology-Legacy Content, 1975
- Measurement of brain uptake of radiolabeled substances using a tritiated water internal standardBrain Research, 1970
- The Permeability of Capillaries in Various Organs as Determined by Use of the ‘Indicator Diffusion’ MethodActa Physiologica Scandinavica, 1963