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Limited Blood‐Brain Barrier Transport of Polyamines
Author(s) -
Shin W.W.,
Fong W.F.,
Pang S.F.,
Wong Patrick C.L.
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb08724.x
Subject(s) - putrescine , spermine , spermidine , chemistry , polyamine , blood–brain barrier , arginine , biophysics , medicine , biochemistry , endocrinology , biology , central nervous system , enzyme , amino acid
Transport of polyamines across the blood‐brain barrier of adult rats was examined by measuring the amount of radioactivity that reached the forebrain 5 s after a “bolus’ intracarotid injection. The values were expressed by the brain uptake index (BUI), which is the percentage of material transported in relation to freely diffusible water in a single passage through the brain. Transport was restricted as indicated by the respective BUI values, presented as means ± SD (number of animals): putrescine, 5.3 ± 0.8 (11); spermidine, 6.1 ± 1.3 (7); and spermine, 5.8 ± 0.5 (4). A kinetic study of the transport of [ 14 C]putrescine showed that transport due to passive diffusion accounted for the majority of the observed influx (66% at 1 m M putrescine). However, a small saturable component exists with a K m value of 4–5 m M and a V max of 30 nmol ± min −1 ± g −1 . This K m value is considerably higher than the circulating levels of the polyamine in the normal mature animal, and thus is unlikely to be of physiological significance. Competition studies indicated that putrescine does not interact with carriers for adenosine, arginine, choline, or leucine.