Effects T3 of Triiodothyronine
T3 increases the basal metabolic rate and thus increases the body’s oxygen and energy consumption. The basal metabolic rate is the minimal caloric requirement needed to sustain life in a resting individual. T3 acts on the majority of tissues within the body, with a few exceptions including the spleen and testis. It increases the production of the Na+/K+ -ATPase and in general increases the turnover of different endogenous macromolecules by increasing their synthesis and degradation.
Protein
T3 stimulates the production of RNA Polymerase I and II and therefore increases the rate of protein synthesis. It also increases the rate of protein degradation and in excess the rate of protein degradation exceeds the rate of protein synthesis. In such situations the body may go into negative ion balance.
Glucose
T3 potentiates the effects of the β-adrenergic receptors on the metabolism of glucose. It therefore increases the rate of glycogen breakdown and glucose synthesis in gluconeogenesis. It also potentiates the effects of insulin, which have opposing effects.
Lipids
T3 stimulates the breakdown of cholesterol and increases the number of LDL receptors, therefore increasing the rate of lipolysis.
T3 also affects the cardiovascular system. It increases the cardiac output by increasing the heart rate and force of contraction. This results in increased systolic blood pressure and decreased diastolic blood pressure. The latter two effects act to produce the typical bounding pulse seen in hyperthyroidism.
T3 also has profound effect upon the developing embryo and infants. It affects the lungs and influences the postnatal growth of the central nervous system. It stimulates the production of myelin, neurotransmitters and axon growth. It is also important in the linear growth of bones.
Tags: Antiseptics, Iodinated tyrosine derivatives, Iodine, Iodine compounds, Medical hygiene, Organoiodides
This entry was posted
on Thursday, June 18th, 2009 at 5:00 am and is filed under Uncategorized.
You can follow any responses to this entry through the RSS 2.0 feed.
You can leave a response, or trackback from your own site.
Reverse triiodothyronine (reverse T3, or rT3) is a molecule which is an isomer of triiodothyronine (T3). It is derived from thyroxine (T4) through the use of deiodinase.rT3, unlike T3, does not stimulate thyroid hormone receptors. However, rT3 nonetheless binds to these receptors, thereby blocking the action of T3. Under stress conditions, the adrenal glands produce excess amounts of cortisol. Cortisol inhibits the conversion of T4 to T3, thus shunting T4 conversion from T3 towards rT3. Consequently, there is a widespread shutdown in T3 binding across the body. This condition is termed Reverse T3 Dominance. It results in reduced body temperature,
The T3 (and T4) bind to nuclear receptors, thyroid receptors. However, T3 (and T4) are not very lipophilic and as a result, are unable to pass through the phospholipid bilayers. They therefore have specific transport proteins on the cell membranes of the effector organs which allow the T3 and T4 to pass into the cells. The thyroid receptors bind to response elements in gene promoters and thus enabling them to activate or inhibit transcription. The sensitivity of a tissue to T3 is modulated through the thyroid receptors.
Thyroid hormones (T4 and T3) are produced by the follicular cells of the thyroid gland and are regulated by TSH made by the thyrotrophs of the anterior pituitary gland. Because the effects of T4 in vivo are mediated via T3 (T4 is converted to T3 in target tissues; T3 is 3- to 5- fold more active than T4).
Thyroxine (3,5,3',5'-tetraiodothyronine) is produced by follicular cells of the thyroid gland. It is produced as the precursor thyroglobulin (this is not the same as TBG), which is cleaved by enzymes to produce active T4.
Thyroxine is produced by attaching iodine atoms to the ring
Triiodothyronine, C15H12I3NO4, also known as T3, is a thyroid hormone.
Thyroid-stimulating hormone (TSH) activates the production of thyroxine (T4) and T3. This process is under regulation. In the thyroid, T4 is converted to T3. TSH is inhibited mainly by T3. The thyroid gland releases greater amounts of T4 than T3, so plasma concentrations of T4 are 40-fold higher than those of T3. Most of the circulating T3 is formed peripherally by deiodination of T4 (85%), a process that involves the removal of iodine from carbon 5 on the outer ring of T4. Thus, T4 acts as prohormone for T3.
This thyroid hormone
A doctor may add a medication with a different mode of action to bolster the effect of an antidepressant in cases of treatment resistance.[145] Medication with lithium salts has been used to augment antidepressant therapy in those who have failed to respond to antidepressants alone.[146] Furthermore, lithium dramatically decreases the suicide risk in recurrent depression.[147] Addition of a thyroid hormone, triiodothyronine may work as well as lithium, even in patients with normal thyroid function.[148] Addition of atypical antipsychotics when the patient has not responded to an antidepressant is also known to increase the effectiveness of antidepressant drugs, albeit offset by
Liothyronine sodium is the L-isomer of triiodothyronine (T3), a form of thyroid hormone used to treat hypothyroidism and myxedema coma. It is marketed under the brand name Cytomel (or Tertroxin in Australia).
T3 is metabolically active hormone that is produced from T4. T4 is deiodinated by two deiodinases to produce the active triiodothyronine:
1. Type I present within the liver and accounts for 80% of the deiodination of T4
2. Type II present within the pituitary.
T4 is synthesised in the thyroid gland follicular cells as follows.
1. The Na+/I- symporter transports two sodium ions across the basement membrane of the follicular cells along with an iodine ion. This is secondary active transporter that utilises the concentration gradient of Na+ to move I- against its concentration gradient.
2. I- is moved across the apical membranae into the
The thyroid hormones, thyroxine (T4) and triiodothyronine (T3), are tyrosine-based hormones produced by the thyroid gland. An important component in the synthesis of thyroid hormones is iodine. The major form of thyroid hormone in the blood is thyroxine (T4), which has a longer half life than T3. The ratio of T4 to T3 released in the blood is roughly 20 to 1. Thyroxine is converted to the active T3 (three to four times more potent than T4) within cells by deiodinases (5'-iodinase). These are further processed by decarboxylation and deiodination to produce iodothyronamine (T1a) and thyronamine (T0a).
Radiation therapy is in itself painless. Many low-dose palliative treatments (for example, radiotherapy to bony metastases) cause minimal or no side effects, although short-term pain flare up can be experienced in the days following treatment due to oedema compressing nerves in the treated area. Treatment to higher doses causes varying side effects during treatment (acute side effects), in the months or years following treatment (long-term side effects), or after re-treatment (cumulative side effects). The nature, severity, and longevity of side effects depends on the organs that receive the radiation, the treatment itself (type of radiation, dose, fractionation, concurrent chemotherapy), and
Side effects of prazepam are less profound than with other benzodiazepines.[7] Excessive drowsiness and with longer term use drug dependence are the most common side effects of prazepam.[8][9] Side effects such as fatigue or "feeling spacey" can also occur but less commonly than with other benzodiazepines. Other side effects include feebleness, clumsiness, lethargic, clouded thinking and mentally slowness.[10][11][12]
Leave a Reply