Neurochemical research
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Neurochemical research · Jul 1989
Triiodothyronine bound to red blood cells is not available for transport through the blood-brain barrier.
Many steroid and thyroid hormones and some drugs are bound by circulating red cells. Red cell-bound ligand may not be physiologically inert, as recent studies show that red cell-bound drug is available for uptake by brain. ⋯ The fraction of circulating T3 available for uptake in vivo in the presence of 0, 2, 5, 10, 22, or 44% red cells was essentially identical to the fraction of [125I]T3 unbound in vitro. Therefore, [125I]T3 bound to red cells obtained from normal volunteers is not available for uptake by brain in vivo.