Hyperpolarization of thyroid cells in vitro by thyrotropin and cyclic AMP

1976 ◽  
Vol 231 (1) ◽  
pp. 52-55 ◽  
Author(s):  
R Batt ◽  
JM McKenzie
Keyword(s):  
Cyclic Amp ◽  
Short Term ◽  
Thyroid Cells ◽  
Low Concentrations ◽  
Thyroid Glands ◽  
The Relationship ◽  
Effect Of Feeding ◽  
Mouse Thyroid

With the use of microelectrodes, membrane potential (MP) was measured in mouse thyroid glands in vitro. A basal resting MP of about -39 mV was confirmed. The initial effect of feeding a low-iodine diet (6-12 days) was hyperpolarization, up to -47 m V; chronic low-iodine diet led to depolarization. Low concentrations of thyrotropin (less than 3 mU/ml superfusate) caused hyperpolarization and high ones (greater than 10 mU/ml) led to depolarization. Cyclic AMP (10(-3) M), dibutyryl cyclic AMP (1.2 X 10(-4) M or 1.2 X 10(-3) M) and theophylline (10(-2) or 10(-3) M) caused similar hyperpolarization: D- and DL-propranolol (5 X 10(-5) -5 X 10(-4) M) produced depolarization and inhibited hyperpolarization by thyrotropin. Conclusions are that hyperpolarization is a consequence of short-term increased secretion of thyrotropin in vivo or of low (near physiological) concentrations in vitro; these effects are probably mediated by cyclic AMP. The relationship to and mechanism of depolarization resulting from chronic enhanced endogenous secretion or high in vitro concentrations of thyrotropin are unknown.

IN-VITRO STUDIES OF NORMAL HUMAN THYROID CELLS: RESPONSES TO THYROTROPHIN AND DIBUTYRYL CYCLIC AMP

1977 ◽  
Vol 72 (1) ◽  
pp. 87-96 ◽  
Author(s):  
S. P. BIDEY ◽  
P. MARSDEN ◽  
J. ANDERSON ◽  
C. G. McKERRON ◽  
H. BERRY
Keyword(s):  
Cyclic Amp ◽  
Thyroid Tissue ◽  
Three Dimensional ◽  
Human Thyroid ◽  
Dibutyryl Cyclic Amp ◽  
Iodide Uptake ◽  
Thyroid Cells ◽  
Normal Human

SUMMARY Follicular cells isolated from normal human thyroid tissue have been cultured for up to 140 h with bovine thyrotrophin (TSH) or dibutyryl cyclic AMP (DBcAMP). Both compounds induced marked reorganization of the cells into three-dimensional follicular structures, whilst non-supplemented cells assumed a monolayer form. Cultures treated initially with TSH or DBcAMP showed a greater iodide uptake capacity, in comparison with unsupplemented cultures, in which iodide uptake was markedly diminished after 24 h. The release of tri-iodothyronine (T3) and thyroxine (T4) into the medium was determined by radioimmunoassay. Both TSH- and DBcAMP-treated cells showed a significant increase in iodothyronine output compared with unsupplemented control cells. In contrast to the 'classical' TSH-induced depression of the T4:T3 ratio in vivo, an increase in the ratio was observed for both TSH- and DBcAMP-supplemented cells in vitro. The ratio was also significantly greater after TSH than after DBcAMP, and possible implications of this finding are discussed.

A COMPARISON OF THE IN-VITRO ACTIONS OF THYROID-STIMULATING HORMONE AND CYCLIC 3′,5′-ADENOSINE MONOPHOSPHATE ON THE MOUSE THYROID GLAND

1969 ◽  
Vol 43 (3) ◽  
pp. 477-485 ◽  
Author(s):  
JANICE M. ENSOR ◽  
D. S. MUNRO
Keyword(s):  
Cyclic Amp ◽  
Culture Medium ◽  
Adenosine Monophosphate ◽  
Thyroid Stimulating Hormone ◽  
Vitro Assay ◽  
Thyroid Glands ◽  
Influence Of Tsh ◽  
Mouse Thyroid ◽  
Stimulating Hormone

SUMMARY In the in-vitro assay of Brown & Munro (1967) thyroid-stimulating hormone (TSH) increased the release of radioactive iodine from mouse thyroid glands labelled with 131i during life. Paper chromatography showed that TSH increased the 131I-labelling of thyroxine and tri-iodothyronine both in the culture medium and in hydrolysates of the thyroids. Cyclic 3′,5′-adenosine monophosphate (cyclic AMP) also increased 131I release in this assay and increased the 131I-labelling of thyronines in the culture medium. The effects on thyroid hydrolysates were less striking. Theophylline potentiated the influence of TSH and cyclic AMP in the assay and, by itself, increased 131I release and the labelling of iodothyronines in the thyroid without altering the distribution of 131I in the culture medium. The implications of these results are discussed.

PITUITARY GROWTH HORMONE AND THE GLUCOSE UTILIZATION OF RAT DIAPHRAGM

1955 ◽  
Vol 12 (1) ◽  
pp. 50-56 ◽  
Author(s):  
J. H. OTTAWAY ◽  
R. D. BULBROOK
Keyword(s):  
Growth Hormone ◽  
Glucose Uptake ◽  
Glucose Utilization ◽  
Rat Diaphragm ◽  
Pituitary Growth Hormone ◽  
Low Concentrations ◽  
High Concentrations ◽  
The Relationship

SUMMARY Growth hormone has been reported to cause either a depression or a stimulation of the glucose uptake of isolated rat diaphragm. The present paper describes further work on the two effects. 1. Anaerobic conditions during the preparation of the diaphragm for incubation affect the glucose uptake and alter the response of the muscle to growth hormone. By controlling the oxygen tension in the diaphragm immediately after excision, variation of the glucose uptake and the effect of the hormone is reduced. 2. Solutions of growth hormone were found to be extremely labile, but, by rigidly standardizing the method of preparing solutions, consistent results were obtained. 3. The relationship between the concentration of growth hormone and its effect on the glucose uptake of isolated diaphragm was investigated separately for muscle saturated with oxygen and with nitrogen. With oxygenated muscle at high concentrations the hormone stimulates, and at low concentrations depresses, the rate of glucose uptake. 4. The mode of action of growth hormone in vitro and in vivo is discussed.

Effects of thyrotrophin stimulation for two hours on mouse thyroid cyclic AMP levels in vivo and in vitro

Life Sciences ◽  
1982 ◽  
Vol 31 (23) ◽  
pp. 2583-2586 ◽  
Author(s):  
Bo Ahrén ◽  
Åsa Gustafson ◽  
Pavo Hedner
Keyword(s):  
Cyclic Amp ◽  
Mouse Thyroid

scholarly journals In Vitro and In Vivo Study of the Short-Term Vasomotor Response during Epileptic Seizures

2020 ◽  
Vol 10 (12) ◽  
pp. 942
Author(s):  
Anna Volnova ◽  
Vassiliy Tsytsarev ◽  
Maria Ptukha ◽  
Mikhail Inyushin
Keyword(s):  
Epileptic Seizures ◽  
Brain Disorders ◽  
Seizure Onset ◽  
Short Term ◽  
In Vivo Experiments ◽  
Different Types ◽  
Vasomotor Activity ◽  
The Relationship

Epilepsy remains one of the most common brain disorders, and the different types of epilepsy encompass a wide variety of physiological manifestations. Clinical and preclinical findings indicate that cerebral blood flow is usually focally increased at seizure onset, shortly after the beginning of ictal events. Nevertheless, many questions remain about the relationship between vasomotor changes in the epileptic foci and the epileptic behavior of neurons and astrocytes. To study this relationship, we performed a series of in vitro and in vivo experiments using the 4-aminopyridine model of epileptic seizures. It was found that in vitro pathological synchronization of neurons and the depolarization of astrocytes is accompanied by rapid short-term vasoconstriction, while in vivo vasodilation during the seizure prevails. We suggest that vasomotor activity during epileptic seizures is a correlate of the complex, self-sustained response that includes neuronal and astrocytic oscillations, and that underlies the clinical presentation of epilepsy.

THE BIOSYNTHESIS OF THYROXINE: INCORPORATION OF [U-14C]TYROSINE INTO THYROGLOBULIN BY MOUSE THYROID GLANDS IN VIVO AND IN VITRO

1973 ◽  
Vol 56 (2) ◽  
pp. 173-185 ◽  
Author(s):  
W. H. WAIN
Keyword(s):  
Amino Acids ◽  
Thyroid Lobe ◽  
In Vitro System ◽  
Electrophoretic Separations ◽  
Thyroid Glands ◽  
Mouse Thyroid

SUMMARY The incorporation in vivo of [U-14C]tyrosine into 19S thyroglobulin by mice was achieved to a level of 2·85 c.p.m./μg. This level of incorporation was insufficient to permit the isolation of 14C-labelled iodinated tyrosines or residues. Isolated mouse thyroid lobes were used as an in-vitro system for the synthesis of 19S thyroglobulin. The lobes continued to incorporate 131I into 19S thyroglobulin for at least 48 h and this incorporation of iodine was specifically inhibited by propylthiouracil. The isolated mouse thyroid lobe in-vitro system was used to incorporate 14C-labelled amino acids into 19S thyroglobulin. [U-14C]Tyrosine was incorporated to a level of 1150 c.p.m./μg. Electrophoretic separations of enzymic hydrolysates of [14C]tyrosine-labelled 19S thyroglobulin showed the presence of [14C]tyrosine, [14C]monoiodotyrosine, [14C]di-iodotyrosine and [14C]thyroxine. The presence of [14C]tyrosine, [14C]monoiodotyrosine and [14C]thyroxine was demonstrated by chromatography of the eluates from the electrophoretic separations. The results provide evidence for the utilization of tyrosyl residues within the thyroglobulin molecule for iodination and subsequent coupling to form thyroxine.

scholarly journals Regulation of urea and citrulline synthesis under physiological conditions

1993 ◽  
Vol 292 (1) ◽  
pp. 241-247 ◽  
Author(s):  
G Beliveau Carey ◽  
C W Cheung ◽  
N S Cohen ◽  
S Brusilow ◽  
L Raijman
Keyword(s):  
Urea Synthesis ◽  
Substrate Availability ◽  
Carbamoyl Phosphate ◽  
Short Term ◽  
Two Factors ◽  
Moment Control ◽  
Citrulline Synthesis ◽  
The Relationship

Information on the regulation of urea synthesis in vivo was obtained by examining the relationship between ureagenesis in vivo, citrulline synthesis in vitro, and two factors currently hypothesized to exert short-term regulation of this pathway: the liver mitochondrial content of N-acetylglutamate (NAG) and substrate availability. Rats meal-fed for 4 h every day (4-20 schedule) or for 8 h every other day (8-40 schedule) were used. (1) The citrulline-synthesizing capacity of mitochondria from livers of rats on the 8-40 schedule exceeded the corresponding velocity of urea synthesis in vivo at all time points studied. (2) Mitochondrial NAG in these livers increased from 127 +/- 32 pmol/mg of protein at 0 h to 486 +/- 205 pmol/mg at 3 h after the start of a meal, and decreased thereafter, but the correlation between NAG content and the velocity of citrulline synthesis was not simple, suggesting that NAG is not the only determinant of the state of activation of carbamoyl phosphate synthase I. (3) In rats on the 4-20 schedule killed 1 h after the start of the meal, the liver content of ornithine, citrulline, arginine, glutamate, alanine and urea increased 2.1-12-fold with respect to the values at 0 h; glutamine decreased by 39%. (4) The combined findings indicate that in vivo, moment-to-moment control of the velocity of urea synthesis is exerted by substrate availability. (5) Digestion limits the supply of substrate to the liver, and prevents its ureagenic capacity from being overwhelmed following a protein-containing meal.

A NEW IN VITRO ASSAY FOR THYROIDSTIMULATING HORMONE

1967 ◽  
Vol 38 (4) ◽  
pp. 439-449 ◽  
Author(s):  
JILL BROWN ◽  
D. S. MUNRO
Keyword(s):  
Radioactive Iodine ◽  
Thyroid Stimulating Hormone ◽  
Vitro Assay ◽  
Line Parallel ◽  
Thyroid Glands ◽  
Long Acting ◽  
Response Line ◽  
Mouse Thyroid

SUMMARY A new in vitro assay for thyroid-stimulating hormone (TSH) is described. The parameter of TSH action is the discharge of radioactive iodine from mouse thyroid glands labelled with 131I in vivo. The assay is sensitive to human TSH and gave consistent results during 1 yr. without seasonal variation. A potent preparation of long-acting thyroid stimulator gave a dose-response line parallel with human TSH. Fresh human serum was toxic to the assay preparation so that circulating TSH levels cannot be measured.

RELEASE OF CYCLIC AMP FROM THYROID CELLS IN VITRO

1978 ◽  
Vol 89 (4) ◽  
pp. 693-700 ◽  
Author(s):  
Bo Ahrén ◽  
Åsa Gustafson ◽  
Pavo Hedner ◽  
Hans Nilsson
Keyword(s):  
Cyclic Amp ◽  
Control Level ◽  
Camp Level ◽  
Cell Content ◽  
Thyroid Cells ◽  
Tissue Protein ◽  
Camp Levels ◽  
Mouse Thyroid ◽  
Quantitative Importance

ABSTRACT Half lobes of mouse thyroid gland were incubated in vitro with TSH. They released cyclic AMP (cAMP) into the medium in amounts depending on the concentration of TSH. The release of cAMP was greatest during the first hour of incubation, then it occurred at a lower rate. With an incubation time of 45 min the medium cAMP levels ranged from 43.0 ± 11.9 pmole per mg tissue protein for controls to 296.5 ± 29.2 pmole per mg tissue protein with 5 mU of TSH in the medium. The tissue cAMP level reached a maximum after 15–30 min of incubation with TSH, then it gradually decreased towards control level during 4 h of incubation. With 25 min of incubation the tissue cAMP level was 28.5 ± 8.8 pmole per mg tissue protein for controls compared to 194.3 ± 27.0 pmole per mg tissue protein with 5 mU TSH in the incubation medium. The release of thyroxine was of the same order during the later part of the 4 h incubation period compared to the first one. The results illustrate the quantitative importance of cAMP release, and the fact that in the later part of the incubaion period the cell content of cAMP was low while the release of thyroxine remained high.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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