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. 2015 May 27;6:107. doi: 10.3389/fphar.2015.00107

Figure 1.

Figure 1

BBDR-HPT axis model schematics for the near-term mother and fetus including the iodide PBPK submodel and thyroid hormone submodels for T4 and T3. Following an oral intake dose, solid arrows with closed arrow heads Inline graphic connecting the individual compartments in the anion PBPK submodel and the T4 volume of distribution represent the blood flows. Thicker arrows with closed arrow heads Inline graphic and thinner open arrows Inline graphic within the compartments denote the NIS mediated active uptake and bidirectional passive diffusion of anions across the thyroidal and placental sub-compartments, respectively. The dashed and dotted lines show the link between the PBPK submodels and the T4 and T3 submodels in both the mother and fetus. Dashed lines leaving the thyroid tissue of the iodide PBPK submodel in both maternal and fetal compartments into the hormone volume of distribution denote hormone production. Dotted lines leaving the hormone volume of distribution denote the recirculation of inorganic iodide released due to hormone metabolism into the PBPK submodel for iodide. The connector symbols from the maternal Inline graphic and fetal Inline graphic volume of distribution for T4 and T3 with solid closed arrows Inline graphic represents the metabolism of T4 to T3. The dotted open arrows Inline graphic in the PBPK submodels and the thyroid hormone submodels represent the urinary (*) and combined urinary and fecal (#) elimination of iodide and thyroid hormones, respectively. PBPK submodel for perchlorate is similar to that of the iodide submodel excluding the organification in the thyroid and the subsequent links to the hormone volume of distributions. Perchlorate and iodide PBPK submodels are connected based on the mode of action of perchlorate and iodide to competitively inhibit each other at the sodium iodide symporter. Figure is taken with permission, is view only and permission must be obtained for any onward reuse (Lumen et al., 2013).