L-Thyroxine sodium salt pentahydrate (Levothyroxine; T4) is a synthetic hormone for the research of hypothyroidism. DIO enzymes convert biologically active thyroid hormone (Triiodothyronine,T3) from L-Thyroxine (T4)^[1].

Deiodinases (DIOs), which catalyse the conversion of thyroxine (pro-hormone) to the active thyroid hormone, are associated with thyroid stimulating hormone (TSH) levels. DIO1 and DIO2 catalyze activation of thyroid hormone secretion in contrast to DIO3 playing role inactivation of the secretion. Activities of DIO1 and DIO2 play pivotal role in the negative feedback regulation of pituitary TSH secretion^[1]. L-Thyroxine (T4) and Triiodothyronine (T3) hormones are known to modulate the expression of ionic channels, pumps and regulatory contractile proteins. Moreover, thyroid hormones have been shown to influence calcium homeostasis and flux responsible for excitation and contractility, with L-Thyroxine and Triiodothyronine modulating its pharmacological control and secretion. In rats fed 12 weeks with the iodine-free diet, a significant decrease in the levels of both Triiodothyronine and L-Thyroxine is observed when compared to the control group fed with standard diet (p<0.001). In the group treated with low doses of L-Thyroxine, an increase in L-Thyroxine levels is observed (p=0.02) while Triiodothyronine levels remain virtually similar to the control group (p=0.19). Rats treated with high doses of L-Thyroxine display a significant increase in both Triiodothyronine and L-Thyroxine circulating concentrations compared to the non-treated hypothyroid group (p<0.001 and p=0.004, respectively) and a significant increase in L-Thyroxine levels when compared to the control values (p=0.03)^[2].

888.93

Solid

C₁₅H₂₀I₄NNaO₉

6106-07-6

L-甲状腺素钠五水合物；左旋甲状腺素钠五水合物

Room temperature in continental US; may vary elsewhere.

4°C, sealed storage, away from moisture

*In solvent : -80°C, 6 months; -20°C, 1 month (sealed storage, away from moisture)

DMSO : ≥ 28 mg/mL(31.50 mM)

H₂O :< 0.1 mg/mL(insoluble)

*"≥" means soluble, but saturation unknown.

请根据产品在不同溶剂中的溶解度选择合适的溶剂配制储备液；一旦配成溶液，请分装保存，避免反复冻融造成的产品失效。
储备液的保存方式和期限：-80℃, 6 months; -20℃, 1 month (sealed storage, away from moisture)。-80℃ 储存时，请在 6 个月内使用，-20℃ 储存时，请在 1 个月内使用。

请根据您的实验动物和给药方式选择适当的溶解方案。以下溶解方案都请先按照In Vitro方式配制澄清的储备液，再依次添加助溶剂：

——为保证实验结果的可靠性，澄清的储备液可以根据储存条件，适当保存；体内实验的工作液，建议您现用现配，当天使用； 以下溶剂前显示的百
分比是指该溶剂在您配制终溶液中的体积占比；如在配制过程中出现沉淀、析出现象，可以通过加热和/或超声的方式助溶

• 1.

  请依序添加每种溶剂： 10% DMSO    40%PEG300   5%Tween-80   45% saline

  Solubility: ≥ 2.5 mg/mL (2.81 mM); Clear solution

  此方案可获得 ≥ 2.5 mg/mL (2.81 mM，饱和度未知) 的澄清溶液。

  以 1 mL 工作液为例，取 100 μL 25.0 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀；向上述体系中加入50 μL Tween-80，混合均匀；然后继续加入 450 μL生理盐水定容至 1 mL。

  将 0.9 g 氯化钠，完全溶解于 100 mL ddH2O 中，得到澄清透明的生理盐水溶液
• 2.

  请依序添加每种溶剂： 10% DMSO    90% (20%SBE-β-CDin saline)

  Solubility: 2.5 mg/mL (2.81 mM); Suspended solution; Need ultrasonic

  此方案可获得 2.5 mg/mL (2.81 mM) 的均匀悬浊液，悬浊液可用于口服和腹腔注射。

  以 1 mL 工作液为例，取 100 μL 25.0 mg/mL 的澄清 DMSO 储备液加到 900 μL20% 的 SBE-β-CD 生理盐水水溶液中，混合均匀。

  将 2 g 磺丁基醚 β-环糊精加入 5 mL 生理盐水中，再用生理盐水定容至 10 mL，完全溶解，澄清透明