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Woodbury
Uptakes of iodide and chloride by primary cultures of mouse astrocytes and neurons.Chow SY, White HS, Yen-Chow YC, Woodbury DM. Neurochem Res. 1989 Oct;14(10):963-9. [abstract only]
"Primary cultures of both mouse astrocytes and neurons accumulate more 125I- than 36Cl- from the medium. The average cell/medium ratio of 125I- of astrocytes (1.01) is greater than that of neurons (0.74), whereas the ratio of 36Cl- of neurons (0.47) is greater than that of astrocytes (0.25). The equilibrium potentials of both 125I- and 36Cl- calculated from the cell/medium ratios in astrocytes and neurons are significantly lower than their corresponding resting transmembrane potentials which suggest that both iodide and chloride are actively transported into both cell types. With respect to different transport inhibitors, thiocyanate is more effective in inhibiting 125I- uptake whereas furosemide is more effective in inhibiting 36Cl- uptake. Radioiodide uptake by mouse astrocytes was directly proportional to the [Na+]o but was not significantly affected by changes of [Cl-]o or [HCO3-]o, except that it is low in bicarbonate-free medium. Radiochloride uptake by astrocytes was inversely related to [Cl-]o and [HCO3-]o and was not affected [Na+]o, except that it was low in sodium-free medium. Radioiodide uptake by neurons was directly related to [Na+]o between 60 and 140 mM and inversely related to [HCO3-]o between 10 and 40 mM, but it was not affected by [Cl-]o. Radiochloride uptake by neurons was directly related to [Cl-]o and to [Na+]o between 60 and 140 mM and was not affected by [HCO3-]o. However, in sodium-free medium both 125I- and 36Cl- uptakes into neurons were higher than those in [Na+]o between 5 and 60 mM. These results indicate that uptake of 125I- and 36Cl- into astrocytes and neurons are different in their ion dependence and that they are under separate regulation."
Radioiodide uptake in brain, CSF, thyroid, and salivary glands of audiogenic seizure mice.Engstrom FL, Chow SY, Kemp JW, Woodbury DM. Epilepsia. 1984 Aug;25(4):518-25. [abstract only]
"DBA/2J (DBA) mice are susceptible to audiogenic seizures (ASs) in an age-dependent manner. Anion transport as measured by radioiodide uptake was determined in thyroid gland, salivary gland, skeletal muscle, cerebral cortex, cerebellum, brainstem, and CSF from these mice at various ages. Anion transport was also determined in C57BL/6J(C57) mice, an AS-resistant strain. In thyroid, DBA mice had an enhanced ability to concentrate iodide at 21 days of age when they have maximal AS susceptibility, as compared with the same-aged C57 mice. This difference in thyroid function was less marked at 40 days of age, when DBA mice are less AS susceptible, and was absent at 110 days of age, when DBA mice are AS resistant. In brain, differences in iodide uptake were also noted between these two strains of mice at 21 days of age. DBA mice had an increased concentration of iodide in CSF, an indication that they have a defect in the transport of iodide out of the CSF across the choroid plexus. In addition, DBA mice had a lower ratio of cerebral cortex to CSF iodide, which suggests that DBA mice have a defect in the transport of this anion into cerebral cortical cells from brain interstitial fluid. These differences in iodide transport in brain decreased with age as the AS susceptibility of DBA mice decreased.
"These results suggest a relation between anion transport in thyroid gland, cerebral cortex, and choroid plexus and AS susceptibility in DBA mice at 21 days of age."
Factors affecting distribution of iodide in brain and cerebrospinal fluid.Reed DJ, Woodbury DM, Jacobs L, Squires R. Am J Physiol. 1965 Oct;209(4):757-64. [citation only]
"The effects of acetazolamide, sodium perchlorate, ouabain, and of iodide loading on the processes controlling I131 and inulin-C14 distribution in the brain and CSF were studied in nephrectomized rats. It was observed that the first three drugs increased the concentration of both iodide and inulin in the brain and CSF after intracisternal administration of the tracers. It was concluded that acetazolamide reduced the rate of formation and flow of CSF, that perchlorate primarily decreased active iodide transport, and that ouabain slightly reduced CSF formation and flow. Iodide loading increased the CSF/plasma iodide ratio, expressed as percent (CSF iodide space), from 1.97 to 42.17, and the comparable values for brain were 2.02 and 11.76, respectively.
"The results suggest that the primary factors in the control of iodide distribution in the CNS are the following: 1) an active iodide transport system between CSF and blood, 2) limited permeability to iodide of the structures between blood and CSF and between blood and brain, and 3) relatively free diffusion of iodide between brain and CSF."
Kinetics of movement of iodide, sucrose, inulin and radio-iodinated serum albumin in the central nervous system and cerebrospinal fluid of the rat.Reed DJ, Woodbury DM J Physiol. 1963 Dec;169:816-50.
"The nature of the blood-brain, blood-CSF, and CSF brain interfaces (‘blood-brain barrier’) was investigated by comparing the kinetics of movement and the tissue distribution of four isotopically labeled tracers in the rat… 131-I-iodide, 14-C-sucrose, 14-C-inulin, and radio-iodinated serum albumin (RISA)….”
"Iodide was found to distribute rapidly (about 5 min) in all tissues studied after either route of administration…. The movement of iodide between CFS and plasma after administration by either route was extremely rapid compared to that of the other tracers studied….”
"Following IV administration of RISA, all the brain radioactivity could be accounted for by the residual blood and free iodide….”
"Some evidence has been presented to suggest that iodide is actively removed from the CSF. Possible mechanisms which might accomplish this have been discussed: these include a specific iodide pump and bulk flow of fluid from the blood into the CSF, from the CSF into the brain tissue, and from the brain back into the blood.”
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