INTERACTION OF THYROID-STIMULATING ANTIBODIES WITH THE HUMAN THYROTROPHIN RECEPTOR

1977 ◽  
Vol 75 (3) ◽  
pp. 401-407 ◽  
Author(s):  
B. REES SMITH ◽  
GWYNETH A. PYLE ◽  
V. B. PETERSEN ◽  
R. HALL
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Receptor Site ◽  
Kinetic Studies ◽  
Dependent Manner ◽  
Similar Time ◽  
Thyroid Stimulating Antibodies ◽  
Binding Data ◽  
Rate Limiting ◽  
Dose Dependent

Thyroid-stimulating antibodies (TSAb) were found to inhibit the binding of labelled thyrotrophin (TSH) to thyroid membranes in a dose-dependent manner and this effect was localized in the Fab part of the TSAb molecule. Analysis of the binding data suggested that TSAb and TSH bound to the same receptor site. Production of cyclic AMP by the thyroid membranes was stimulated by TSAb and TSAb–Fab with a similar time course to that observed with TSH. Kinetic studies indicated that the binding of TSAb to the thyroid membranes was not rate-limiting in the process of stimulation of cyclic AMP production.

scholarly journals Calcium metabolism in rat hepatocytes

1978 ◽  
Vol 170 (3) ◽  
pp. 615-625 ◽  
Author(s):  
S Foden ◽  
P J Randle
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Rat Hepatocytes ◽  
Ionophore A23187 ◽  
Total Calcium ◽  
Free Medium ◽  
Adrenergic Agonists ◽  
Calcium Efflux ◽  
Similar Time ◽  
Carbonyl Cyanide

1. The total calcium concentration in rat hepatocytes was 7.9 microgram-atoms/g dry wt.; 77% of this was mitochondrial. Approx. 20% of cell calcium exchanged with 45Ca within 2 min. Thereafter incorporation proceeded at a low rate to reach 28% of total calcium after 60 min. Incorporation into mitochondria showed a similar time course and accounted for 20% of mitochondrial total calcium after 60 min. 2. The alpha-adrenergic agonists phenylephrine and adrenaline + propranolol stimulated incorporation of 45Ca into hepatocytes. Phenylephrine was shown to increase total calcium in hepatocytes. Phenylephrine inhibited efflux fo 45Ca from hepatocytes perifused with calcium-free medium. 3. Glucagon, dibutryl cyclic AMP and beta-adrenergic agonists adrenaline and 3-isobutyl-1-methyl-xanthine stimulated calcium efflux from hepatocytes perifused with calcium-free medium. The effect of glucagon was blocked by insulin. Insulin itself had no effect on calcium efflux and it did not affect the response to dibutyryl cyclic AMP. 4. Incorporation of 45Ca into mitochondria in hepatocytes was stimulated by phenylephrine and inhibited by glucagon and by carbonyl cyanide p-trifluoromethoxyphenylhydrazone. The effect of glucagon was blocked by insulin. 5. Ionophore A23187 stimulated hepatocyte uptake of 45Ca, uptake of 45Ca into mitochondria in hepatocytes and efflux of 45Ca into a calcium-free medium.

Mutant analysis suggests that cyclic GMP mediates the cyclic AMP-induced Ca2+ uptake in Dictyostelium

1991 ◽  
Vol 99 (1) ◽  
pp. 187-191
Author(s):  
S. Menz ◽  
J. Bumann ◽  
E. Jaworski ◽  
D. Malchow
Keyword(s):  
Cyclic Amp ◽  
Mutant Strain ◽  
Cyclic Gmp ◽  
Parental Strain ◽  
Dependent Manner ◽  
Heavy Chains ◽  
Signal Relay ◽  
Sensitive Electrode ◽  
Dose Dependent ◽  
Cyclic Amp Synthesis

Previous work has shown that streamer F (stmF) mutants of Dictyostelium discoideum exhibit prolonged chemotactic elongation in aggregation fields. The mutants carry an altered structural gene for cyclic GMP phosphodiesterase resulting in low activities of this enzyme. Chemotactic stimulation by cyclic AMP causes a rapid transient increase in the cyclic GMP concentration followed by association of myosin heavy chains with the cytoskeleton. Both events persist several times longer in stmF mutants than in the parental strain, indicating that the change in association of myosin with the cytoskeleton is transmitted directly or indirectly by cyclic GMP. We measured the cyclic AMP-induced Ca2+ uptake with a Ca(2+)-sensitive electrode and found that Ca2+ uptake was prolonged in stmF mutants but not in the parental strain. The G alpha 2 mutant strain HC33 (fgdA), devoid of InsP3 release and receptor/guanylate cyclase coupling, lacked Ca2+ uptake. However, the latter response and cyclic GMP formation were normal in the signal-relay mutant strain agip 53 where cyclic AMP-stimulated cyclic AMP synthesis is absent. LiCl, which inhibits InsP3 formation in Dictyostelium, blocked Ca2+ uptake in a dose-dependent manner. The data indicate that the receptor-mediated Ca2+ uptake depends on the InsP3 pathway and is regulated by cyclic GMP. The rate of Ca2+ uptake was correlated in time with the association of myosin with the cytoskeleton, suggesting that Ca2+ uptake is involved in the motility response of the cells.

Intracerebroventricular injection of prostaglandin E2 increases splenic sympathetic nerve activity in rats

1995 ◽  
Vol 269 (3) ◽  
pp. R662-R668 ◽  
Author(s):  
T. Ando ◽  
T. Ichijo ◽  
T. Katafuchi ◽  
T. Hori
Keyword(s):  
Prostaglandin E2 ◽  
Sympathetic Nerve ◽  
Time Course ◽  
Sympathetic Nerve Activity ◽  
Dependent Manner ◽  
Central Administration ◽  
Nerve Activity ◽  
High Doses ◽  
Alpha Chloralose ◽  
Dose Dependent

The effects of central administration of prostaglandin E2 (PGE2) and its selective agonists on splenic sympathetic nerve activity (SNA) were investigated in urethan- and alpha-chloralose-anesthetized rats. An intra-third-cerebroventricular (13V) injection of PGE2 (0.1-10 nmol/kg) increased splenic SNA in a dose-dependent manner. An I3V injection of an EP1 agonist, 17-phenyl-omega-trinor PGE2 (1-30 nmol/kg), also resulted in a dose-dependent increase in splenic SNA, with a time course similar to that of PGE2-induced responses. In contrast, EP2 agonists, butaprost (10-100 nmol/kg I3V) and 11-deoxy-PGE1 (10-100 nmol/kg I3V), had no effect on splenic SNA. An I3V injection of M & B-28767 (an EP3/EP1 agonist, EP3 >> EP1) increased splenic SNA only at high doses (10-100 nmol/kg). Pretreatment with an EP1 antagonist, SC-19220 (200 and 500 nmol/kg), completely blocked the responses of splenic SNA to PGE2 (0.1 nmol/kg) and M & B-28767 (10 nmol/kg), respectively. These findings indicate that brain PGE2 increases splenic SNA through its action on EP1 receptors.

Time- and dose-dependent differential upregulation of three genes by 17β-estradiol in endothelial cells

2002 ◽  
Vol 92 (3) ◽  
pp. 1064-1073 ◽  
Author(s):  
Amparo C. Villablanca ◽  
Kristine A. Lewis ◽  
John C. Rutledge
Keyword(s):  
Endothelial Cells ◽  
Vascular Function ◽  
Time Course ◽  
Plasminogen Activator Inhibitor ◽  
Hormone Treatment ◽  
Plasminogen Activator Inhibitor 1 ◽  
Similar Time ◽  
Differential Display Analysis ◽  
17Β Estradiol ◽  
Dose Dependent

The purpose of this study was to identify genetic targets in the vasculature for estrogen by profiling genes expressed in female human aortic endothelial cells exposed to various doses of 17β-estradiol at differing concentrations and for differing periods of time. Our approach employed a RT-PCR-based cloning strategy of DNA differential display analysis, with differential expression verified by semiquantitative PCR performed with gene-specific primers. A significant increase in mRNA expression in response to 17β-estradiol was observed for the following three genes: aldose reductase (3.4-fold), caspase homologue-α protein (4.2-fold), and plasminogen activator inhibitor-1 intron e (2.3-fold). For all three upregulated genes, estradiol-induced upregulation occurred with a similar time course and temporally clustered to the first 24 h after hormone treatment. In addition, the effect of estradiol dose on gene expression was consistent and occurred at physiological concentrations. Our results describe previously uncharacterized estradiol-sensitive time- and dose-dependent regulation of genes with potential importance to vascular function in human endothelial cells.

scholarly journals Endogenous H2S is required for hypoxic sensing by carotid body glomus cells

2012 ◽  
Vol 303 (9) ◽  
pp. C916-C923 ◽  
Author(s):  
Vladislav V. Makarenko ◽  
Jayasri Nanduri ◽  
Gayatri Raghuraman ◽  
Aaron P. Fox ◽  
Moataz M. Gadalla ◽  
...  
Keyword(s):  
Carotid Body ◽  
Time Course ◽  
Channel Blocker ◽  
Primary Site ◽  
Dependent Manner ◽  
Free Medium ◽  
Adult Rats ◽  
Glomus Cells ◽  
Dose Dependent ◽  
Carotid Body Glomus Cells

H2S generated by the enzyme cystathionine-γ-lyase (CSE) has been implicated in O2 sensing by the carotid body. The objectives of the present study were to determine whether glomus cells, the primary site of hypoxic sensing in the carotid body, generate H2S in an O2-sensitive manner and whether endogenous H2S is required for O2 sensing by glomus cells. Experiments were performed on glomus cells harvested from anesthetized adult rats as well as age and sex-matched CSE+/+ and CSE−/− mice. Physiological levels of hypoxia (Po2 ∼30 mmHg) increased H2S levels in glomus cells, and dl-propargylglycine (PAG), a CSE inhibitor, prevented this response in a dose-dependent manner. Catecholamine (CA) secretion from glomus cells was monitored by carbon-fiber amperometry. Hypoxia increased CA secretion from rat and mouse glomus cells, and this response was markedly attenuated by PAG and in cells from CSE−/− mice. CA secretion evoked by 40 mM KCl, however, was unaffected by PAG or CSE deletion. Exogenous application of a H2S donor (50 μM NaHS) increased cytosolic Ca2+ concentration ([Ca2+]i) in glomus cells, with a time course and magnitude that are similar to that produced by hypoxia. [Ca2+]i responses to NaHS and hypoxia were markedly attenuated in the presence of Ca2+-free medium or cadmium chloride, a pan voltage-gated Ca2+ channel blocker, or nifedipine, an L-type Ca2+ channel inhibitor, suggesting that both hypoxia and H2S share common Ca2+-activating mechanisms. These results demonstrate that H2S generated by CSE is a physiologic mediator of the glomus cell's response to hypoxia.

Mode of Action of the Hypertrehalosaemic Peptides from the American Cockroach

1985 ◽  
Vol 40 (9-10) ◽  
pp. 670-676 ◽  
Author(s):  
Gerd Gäde
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Mode Of Action ◽  
Glycogen Phosphorylase ◽  
Fat Body ◽  
American Cockroach ◽  
Dependent Manner ◽  
Low Concentrations ◽  
First Time ◽  
Dose Dependent

Abstract Although crude extracts of cockroach (Periplaneta amencana) corpora cardiaca have been shown previously to affect the activity of adenylate cyclase and phosphorylase, we demonstrate in the present study for the first time that low concentrations (0.5 to 5 pmol) of the synthetic myoactive peptides. M I and M II, also affect these systems; these myoactive peptides are identical to the hypertrehalosaemic hormones I and II, and cause an increase in the concentration of the second messenger cyclic AMP in the fat body.In addition, both octapeptides activate fat body glycogen phosphorylase and promote breakdown of fat body glycogen. Both peptides increase the levels to haemolymph carbohydrate in a dose-dependent manner.

Effects of pinacidil on coronary Ca2+-myosin phosphorylation in cold potassium cardioplegia model

2000 ◽  
Vol 279 (3) ◽  
pp. H882-H888 ◽  
Author(s):  
Naruto Matsuda ◽  
Kathleen G. Morgan ◽  
Frank W. Sellke
Keyword(s):  
Time Course ◽  
Dependent Manner ◽  
Coronary Smooth Muscle ◽  
Intracellular Ca ◽  
No Signaling ◽  
Synthase Inhibitor ◽  
Mlc Phosphorylation ◽  
Dose Dependent ◽  
Cardioplegic Solutions

The effects of the potassium (K+) channel opener pinacidil (Pin) on the coronary smooth muscle Ca2+-myosin light chain (MLC) phosphorylation pathway under hypothermic K+cardioplegia were determined by use of an in vitro microvessel model. Rat coronary arterioles (100–260 μm in diameter) were subjected to 60 min of simulated hypothermic (20°C) K+cardioplegic solutions (K+= 25 mM). We first characterized the time course of changes in intracellular Ca2+concentration, MLC phosphorylation, and diameter and observed that the K+cardioplegia-related vasoconstriction was associated with an activation of the Ca2+-MLC phosphorylation pathway. Supplementation with Pin effectively suppressed the Ca2+accumulation and MLC phosphorylation in a dose-dependent manner and subsequently maintained a small decrease in vasomotor tone. The ATP-sensitive K+(KATP)-channel blocker glibenclamide, but not the nitric oxide (NO) synthase inhibitor Nω-nitro-l-arginine methyl ester, significantly inhibited the effect of Pin. K+cardioplegia augments the coronary Ca2+-MLC pathway and results in vasoconstriction. Pin effectively prevents the activation of this pathway and maintains adequate vasorelaxation during K+cardioplegia through a KATP-channel mechanism not coupled with the endothelium-derived NO signaling cascade.

Effect of cocaine and methylecgonidine on intracellular Ca2+ and myocardial contraction in cardiac myocytes

1997 ◽  
Vol 273 (2) ◽  
pp. H893-H901 ◽  
Author(s):  
L. Huang ◽  
J. H. Woolf ◽  
Y. Ishiguro ◽  
J. P. Morgan
Keyword(s):  
Structural Damage ◽  
Time Course ◽  
Crack Cocaine ◽  
Pyrolysis Product ◽  
Myocardial Contraction ◽  
Dependent Manner ◽  
Response Curves ◽  
Inotropic Effects ◽  
Cell Shortening ◽  
Dose Dependent

We evaluated the cardiac effects of the principle pyrolysis product of crack cocaine smoking, methylecgonidine (MEG), in comparison with cocaine. Peak cell shortening and intracellular Ca2+, as detected by the Ca2+ indicator indo 1, were recorded in enzymatically isolated ferret myocytes. Both cocaine and MEG decreased peak cell shortening and peak intracellular Ca2+ concentration ([Ca2+]i) in a dose-dependent manner (10(-8)-10(-4) M). MEG shifted the peak [Ca2+]i-to-peak shortening relationship downward and was more potent than cocaine. Atropine (10(-6) M) upwardly shifted the dose-response curves of MEG, cocaine, and carbachol but not of procaine. The negative inotropic effects of MEG were inhibited by methoctramine, a selective M2 receptor blocker but not by M1 (pirenzepine) or M3 (4-diphenylacetoxy-N-methylpiperidine methiodide) blocking agents. In contrast to cocaine, the effects of large doses of MEG were irreversible over the time course of our experiments, raising the possibility of structural damage. We conclude that MEG acts primarily on M2 cholinergic receptors in the heart to produce acute cardiac intoxication and, in contrast to cocaine, may decrease the myofilament Ca2+ responseness and cause structural damage to myocytes by a direct toxic effect.

Biochemical parameters regulating forward motility initiation in vitro in goat immature epididymal spermatozoa

1998 ◽  
Vol 10 (4) ◽  
pp. 299 ◽  
Author(s):  
Bijay S. Jaiswal ◽  
Gopal C. Majumder
Keyword(s):  
Cyclic Amp ◽  
Sperm Motility ◽  
Biochemical Parameters ◽  
Vital Role ◽  
Dependent Manner ◽  
Alkaline Ph ◽  
Heat Stable ◽  
Heat Stable Protein ◽  
Dose Dependent

An investigation was carried out to analyse the biochemical parameters influencing forward motility (FM) initiation in vitro in the goat caput-epididymal immature spermatozoa. Forward motility was induced in approximately 55% of caput-sperm upon incubation in an alkaline (pH 8.0) modified Ringer’s solution containing theophylline (30 mM) (an inhibitor of cyclic AMP phosphodiesterase), dialysed epi-didymal plasma (EP) and bicarbonate. Both EP and bicarbonate induced sperm motility in a dose-dependent manner, and at saturating doses EP (0.6 mg protein mL–1) and bicarbonate (25 mM) induced FM in approx-imately 38% and 44% of the cells, respectively. The motility-promoting efficacy of EP was attributed to a heat-stable protein termed ‘forward motility protein’ (FMP). Bicarbonate served as an initiator as well as a stabilizer of FM and its action was not dependent on FMP. FMP can induce FM in the caput-sperm, but it is not essential for sperm motility initiation. Alteration of the medium pH from 6.60 to 8.00 caused a marked increase in the EP or bicarbonate-dependent sperm FM initiation, as well as intrasperm pH. At the physio-logical pH, bicarbonate served as a much more potent motility activator than FMP, although both the motility promoters showed maximal efficacy at alkaline pH (~7.8). EP as well as bicarbonate elevated the intrasperm cyclic AMP level. Unlike EP, bicarbonate is capable of increasing intrasperm pH. The intrasperm pH increased from 6.54 0.02 to 6.77 0.03 during sperm transit from caput to cauda. The data are con-sistent with the view that FMP activates sperm forward motility by enhancing the intrasperm cyclic AMP level and that extracellular bicarbonate and pH play a vital role in the initiation of sperm FM during the epi-didymal transit.

scholarly journals Calcium rather than cyclic AMP is an intracellular messenger of parathyroid hormone action on glycogen metabolism in isolated rat hepatocytes

1989 ◽  
Vol 258 (3) ◽  
pp. 889-894 ◽  
Author(s):  
T Mine ◽  
I Kojima ◽  
E Ogata
Keyword(s):  
Parathyroid Hormone ◽  
Cyclic Amp ◽  
Glucose Production ◽  
Rat Hepatocytes ◽  
Free Calcium ◽  
Dependent Manner ◽  
Isolated Rat Hepatocytes ◽  
Glucose Output ◽  
Dose Dependent ◽  
Isolated Rat

The synthetic 1-34 fragment of human parathyroid hormone (1-34hPTH) stimulated glucose production in isolated rat hepatocytes. The effect of 1-34hPTH was dose-dependent and 10(10) M-1-34 hPTH elicited the maximum glucose output, which was approx. 80% of that by glucagon. Although 1-34hPTH induced a small increase in cyclic AMP production at concentrations higher than 10(-9) M, 10(-10) M-1-34hPTH induced the maximum glucose output without significant elevation of cyclic AMP. This is in contrast to the action of forskolin, which increased glucose output to the same extent as 10(-10) M-1-34hPTH by causing a 2-fold elevation of cyclic AMP. In addition to increasing cyclic AMP, 1-34hPTH caused an increase in cytoplasmic free calcium concentration ([Ca2+]c). When the effect of 1-34hPTH on [Ca2+]c was studied in aequorin-loaded cells, low concentrations of 1-34hPTH increased [Ca2+]c: the 1-34hPTH effect on [Ca2+]c was detected at as low as 10(-12) M and increased in a dose-dependent manner. 1-34hPTH increased [Ca2+]c even in the presence of 1 microM extracellular calcium, suggesting that PTH mobilizes calcium from an intracellular pool. In line with these observations, 1-34hPTH increased the production of inositol trisphosphate. These results suggest that: (1) PTH activates both cyclic AMP and calcium messenger systems and (2) PTH stimulates glycogenolysis mainly via the calcium messenger system.

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