Thyrotropin causes a time- and concentration-dependent increase in cytosolic Ca2+ in FRTL-5 rat thyroid cells as measured by Quin2 fluorescence; the half-maximal response occurs in response to 1 X 10(-7) M thyrotropin. The effect of added thyrotropin is the same whether cells have been previously and chronically exposed to thyrotropin or whether they have been thyrotropin "starved" for several ...

Biologically active preparations of 125I-thyrotropin, [3H]thyrotropin, and the [3H]exophthalmogenic factor derived from thyrotropin by partial pepsin digestion have been used to study the binding properties of the thyrotropin receptor on guinea pig retro-orbital tissue plasma membranes. In regard to the optimal conditions of binding, pH, buffer, salt concentrations, and temperature, these prope...

OBJECTIVE The aim of the study was to evaluate the influence of human anti-mouse antibodies on the measurement of thyrotropin. INVESTIGATIONS Samples from 11 patients with measureable human anti-mouse antibody titres (19 micrograms/l-3880 micrograms/l) after radioimmuno-scintigraphy were analysed with 6 different thyrotropin immuno-radiometric assay kits (IRMA). Each sample was analysed in th...

Biologically active preparations of ‘*%thyrotropin, [3H]thyrotropin, and the [3H]exophthalmogenic factor derived from thyrotropin by partial pepsin digestion have been used to study the binding properties of the thyrotropin receptor on guinea pig retro-orbital tissue plasma membranes. In regard to the optimal conditions of binding, pH, buffer, salt concentrations, and temperature, these propert...

background: thyroid autoimmunity may be linked to infertility, in both thyrotropin (tsh)-dependent and tsh-independent fashion. the aim of the present study was to assess this presumed reciprocal relationship of thyroid autoimmunity and pregnancy. methods: tsh and antithyroid peroxidase autoantibodies (anti-tpo) were evaluated retrospectively over an eight-year period in 444 greek women who had...

Phosphatidylinositol, phosphatidylserine, and phosphatidylethanolamine interact with 125I-thyrotropin and inhibit its binding to thyroid plasma membranes; phosphatidylcholine is not similarly effective. The interaction has been monitored by column chromatography on Sephadex G-100 which shows, for example, that 125I-labeled thyrotropin forms an adduct with phosphatidylinositol but not with phosp...

Biologically active bovine 125I-thyrotropin preparations have been prepared, characterized, and used to evaluate the optimal conditions for thyrotropin binding to bovine thyroid plasma membranes in vitro. Binding of 125I-TSH has a pH optimum around 6.0 and is sensitive to the choice and concentration of buffer. Binding is inhibited by salts, especially those containing magnesium and calcium ion...

The present studies demonstrate that iodine depletion increases the sensitivity of the thyroid to the goitrogenic effects of thyrotropin. Iodine depletion was induced by feeding rats a low iodine diet containing propylthiouracil for 10-14 days before hypophysectomy. Accumulation of iodine in the thyroid after hypophysectomy was prevented by continuing the antithyroid drugs in the diet. Doses of...

rats. Adding propylthiouracil or perchlorate to the diet during treatment with thyrotropin did not reduce or augment the goitrogenic response to thyrotropin in iodine-depleted rats. Increasing the level of circulating iodide also did not reduce the goitrogenic response to thyrotropin. The increased sensitivity of the iodine-depleted thyroid gland may provide an explanation for the development o...

We evaluated a double-antibody radioimmunoassay kit for thyrotropin that includes calibrators prepared in a matrix of human serum and involves overnight nonequilibrium. Results were compared with those from two reference assays for thyrotropin. The range of within-assay CVs for the kit for thyrotropin values between 0.9 and 2.4 milli-int. units/L was 2.2 to 5.3%, that for between-assay CVs was ...