Appearance:White to light grey powder
Storage:Store at 8℃-20℃, protect from moisture and light.
Chemical Properties of L-Triiodothyronine:
|Solubility||1、Very slightly soluble in water||pass|
|2、slighty soluble in alcohol||pass|
|3、practically insoluble in most other organic solvents||pass|
|4、disolves in diluted aqueous sodium hydroxide solutions||Pass|
|Identificaton||a) Heat about 50 mg with a few drops of sulfuric acid in
a porcelain crucible: violet vapors of iodine are evolved.
|b)The retention time of the major peak is confirm to
|Loss on Drying||Not more than 4.0%||0.41%|
C=1 in 1M HCl
|+18 ~ +22o||＋20.8o|
|Assay||Not less than 95.0%||99.72%|
|Levothyroxine sodium||Not more than 5.0%||0.09%|
L-triiodothyronine (T3) has previously been shown to substance fast-phase, depolarization-induced 45Ca uptake and [3H-gamma-aminobutyric acid release by rat brain synaptosomes at low nanomolar concentrations comparable to those reported for whole brain. Neverthless, the physiologic importance of these nonnuclear-mediated effects of T3 has remained uncertain, a part because specific mechanisms and the presence of T3 at pesumptive sites of action have not been demonstrated. Isotopic studies showing that L-tetraiodothyronine thyroxine, T4) and T3 are concentrated in synaptosomes, and that T4 is deiodinated to T3 suggested that endogenous levels of T3 in nerve terminals are probably much higher than in other compartments of the brain. In the present study we confirmed that endogenous levels of T3 in nerve terminals are at least eightfold higher, and may be as much as 60-fold higher, than in whole brain. More importantly, we showed that both 125I-labeled T3 and endogenous T3, but not 125I-T4 or endogenous T4, are released from depolarized synaptosomes, primarily by a Ca2+-dependent process. This demonstrates a mechanism for raising the level of T3 within the synapse, where the hormone may interact with pre- and postsynaptic binding (or uptake) sites, and suggests that the peripheral hormone T3 may be a neurotransmitter.Because T3 has a short half-life, divided doses are preferable to a single dose, except where total daily dosing is small. For example, with a dosing of 12.5 mcg.day this would best be taken as a single dose in the morning, but with 50 mcg/day, dividing the daily amount into three or four doses would be better than taking the entire amount at one time.