scholarly journals Salmon calcitonin-induced stimulation of 1α,25-dihydroxycholecalciferol synthesis in rats involving a mechanism independent of adenosine 3′:5′-cyclic monophosphate

1979 ◽  
Vol 184 (2) ◽  
pp. 269-275 ◽  
Author(s):  
N Horiuchi ◽  
H Takahashi ◽  
T Matsumoto ◽  
N Takahashi ◽  
E Shimazawa ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Salmon Calcitonin ◽  
Rat Kidney ◽  
Plasma Concentrations ◽  
Maximal Effect ◽  
Balance Study ◽  
System A ◽  
Dose Dependent Increase ◽  
Dose Dependent

The effect of natural salmon calcitonin on accumulation in plasma of 1 alpha,25-dihydroxy-[3H]cholecalciferol from 25-hydroxy[3H]cholecalciferol in vivo was investigated in vitamin D-deficient thyroparathyroidectomized rats into which graded doses of the hormone were continuously infused by use of a balance study system. A dose-dependent increase in plasma concentrations of 1 alpha,25-dihydroxy[3H]cholecalciferol was observed with calcitonin infusion for 6–30h at a rate greater than 20 M.R.C. m-units/h. Infusion of parathyrin or cyclic AMP produced a similar stimulation [Horiuchi, Suda, Takahashi, Shimazawa & Ogata (1977) Endocrinoly 101, 969–974], but the maximal effect of calcitonin was additive to that of either parathyrin or cyclic AMP. Furthermore concurrent infusion of theophylline (0.5 mumol/h) did not potentiate the effect of submaximal doses (3 and 20 M.R.C. m-units/h) of calcitonin. Plasma concentrations of calcium showed a decrease with calcitonin infusion for 30h, but those of Pi remained unchanged. These results strongly suggest that the rat kidney is endowed with a calcitonin-sensitive 1 alpha-hydroxylase system that is separate from the parathyrin/cyclic AMP system and is independent of changes in plasma Pi.

Leukotriene D4 induces MMP-1, which functions as an IGFBP protease in human airway smooth muscle cells

1996 ◽  
Vol 271 (6) ◽  
pp. L1014-L1022 ◽  
Author(s):  
R. Rajah ◽  
S. E. Nunn ◽  
D. J. Herrick ◽  
M. M. Grunstein ◽  
P. Cohen
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Airway Smooth Muscle Cells ◽  
Igf Binding Proteins ◽  
Leukotriene D4 ◽  
Igf Binding ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Insulin Like Growth Factors

We have previously demonstrated that the asthma-associated proinflammatory eicosanoid leukotriene D4 (LTD4) is comitogenic with insulin-like growth factors (IGF) in airway smooth muscle (ASM) cells. This synergistic effect of LTD4 and IGF on ASM cell growth involves proteolysis of ASM-produced inhibitory IGF-binding proteins (IGFBP). In this report, we analyzed the conditioned media (CM) from LTD4-treated human ASM cells (ASM-LTD4-CM) by Western ligand blotting and demonstrated a marked LTD4-induced reduction in the levels of the intact IGFBP (predominantly IGFBP-2) secreted by these cells. The IGFBP-2 in the ASM-LTD4-CM was identified as lower-molecular-weight fragments by Western immunoblotting. Incubation with 125I-labeled IGFBP demonstrated that an IGFBP protease was induced in the ASM cells in response to LTD4 treatment. Immunodepletion of ASM-LTD4-CM with anti-matrix metalloproteinase (MMP)-1 antibodies demonstrated a dose-dependent reduction of IGFBP proteolysis. Tissue inhibitor of MMP-1 and Batimastat (synthetic) inhibited proteolysis of IGFBP. Immunoblotting the ASM-LTD4-CM with anti-MMP-1 demonstrated a dose-dependent increase in MMP-1 protein. Similar results were also obtained by immunocytochemistry. Collectively, these observations demonstrate that MMP-1 is an IGFBP protease induced by leukotrienes that plays a significant role in modulating IGF action in ASM cells. A similar mechanism may be applicable in vivo in the airways of patients with asthma.

Modulating a modulator: biogenic amines at subthreshold levels potentiate peptide-mediated cardioexcitation of the heart of the tobacco hawkmoth Manduca sexta.

1994 ◽  
Vol 197 (1) ◽  
pp. 377-391 ◽  
Author(s):  
K R Prier ◽  
O H Beckman ◽  
N J Tublitz
Keyword(s):  
Cyclic Amp ◽  
Manduca Sexta ◽  
Biogenic Amine ◽  
Molecular Mechanisms ◽  
Adult Heart ◽  
The Central Nervous System ◽  
Messenger System ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Dependent Mechanism

The central nervous system of the moth Manduca sexta contains a group of myoregulatory neuropeptides, the CAPs (Cardioacceleratory Peptides), which cause a physiologically important, dose-dependent increase in heart rate during wing inflation and flight in adult moths. We report here that the response of the adult heart to a subset of the CAPs, the CAP2S, is potentiated nearly twofold in the chronic presence of subthreshold levels of the biogenic amine octopamine or near-threshold levels of the biogenic amine serotonin. Subthreshold levels of the CAP2S fail to alter the response of the heart to octopamine. We have begun to investigate the molecular mechanisms underlying this potentiation. Previous work on the adult heart has shown that the CAP2s act through an inositol-1,4,5-trisphosphate second-messenger system. Here, we demonstrate that the cardioexcitatory effects of the two amines, in contrast to those of the CAP2S, are both mediated by cyclic AMP. Application to the heart of either 10(-5) moll-1 octopamine or 10(-6)moll-1 serotonin elicits a threefold increase in intracellular cyclic AMP levels. The CAP2S have no effect on cyclic AMP levels in the heart. These results illustrate a mechanism by which the effectiveness of a neurohormone can be increased with minimal cost to the animal. In Manduca sexta, subthreshold levels of octopamine are found in the haemolymph during wing inflation and flight. Thus, it is possible that octopamine up-regulates the effects of CAP2 via a cyclic-AMP-dependent mechanism during these activities.

Direct effects of endothelin in the rat kidney

1990 ◽  
Vol 258 (2) ◽  
pp. F397-F402 ◽  
Author(s):  
T. Katoh ◽  
H. Chang ◽  
S. Uchida ◽  
T. Okuda ◽  
K. Kurokawa
Keyword(s):  
Renal Artery ◽  
Rat Kidney ◽  
Renal Plasma Flow ◽  
Urine Volume ◽  
Fractional Excretion ◽  
Left Renal Artery ◽  
Dependent Manner ◽  
Direct Effects ◽  
Dose Dependent

In the present study, we tested the direct effects of endothelin (ET) on rat kidney in vivo. ET was infused into the left renal artery of anesthetized rats at a rate of 0.5, 5, 20, or 40 pmol/h. ET reduced ipsilateral urine volume (V), clearance of inulin (CIN), and clearance of p-aminohippuric acid (CPAH) in a dose-dependent manner. Thus ET at 20 pmol/h did not change V but decreased renal plasma flow (RPF) and glomerular filtration rate (GFR) by 27.6 +/- 14.3 and 30.8 +/- 10.4%, respectively, in the ipsilateral kidney. ET at 0.5 pmol/h was without effect and at 5 pmol/h had only minor effects on CIN and CPAH of ipsilateral kidney. At 40 pmol/h, ET reduced ipsilateral V, GFR, and RPF by 52.3 +/- 21.4, 58.4 +/- 14.5, and 72.5 +/- 10.6%, respectively. Filtration fraction and fractional excretion of Na remained unchanged during ET infusion. ET, 40 pmol/h, infused into the renal artery together with atrial natriuretic peptide (ANP) at a rate of 12 pmol/h reduced the ipsilateral V, GFR, and RPF by 33.2 +/- 6.3, 26.1 +/- 6.0, and 27.2 +/- 7.1%, respectively, decrements less than those with ET alone. When a calcium-channel blocker nicardipine was infused at a rate of 2.5 micrograms/h into the renal artery together with ET, 20 pmol/h, there was little change in the ipsilateral V, RPF, and GFR; ET, 40 pmol/h, with nicardipine did not change V and decreased GFR and RPF by 25.9 +/- 5.6 and 23.1 +/- 10.8%, respectively, decrements less than those without nicardipine.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The anti-inflammatory peptide Ac-SDKP is released from thymosin-β4 by renal meprin-α and prolyl oligopeptidase

2016 ◽  
Vol 310 (10) ◽  
pp. F1026-F1034 ◽  
Author(s):  
Nitin Kumar ◽  
Pablo Nakagawa ◽  
Branislava Janic ◽  
Cesar A. Romero ◽  
Morel E. Worou ◽  
...  
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Plasma Concentrations ◽  
Potential Candidate ◽  
Thymosin Β4 ◽  
Wild Type ◽  
Prolyl Oligopeptidase ◽  
Anti Inflammatory

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a natural tetrapeptide with anti-inflammatory and antifibrotic properties. Previously, we have shown that prolyl oligopeptidase (POP) is involved in the Ac-SDKP release from thymosin-β4 (Tβ4). However, POP can only hydrolyze peptides shorter than 30 amino acids, and Tβ4 is 43 amino acids long. This indicates that before POP hydrolysis takes place, Tβ4 is hydrolyzed by another peptidase that releases NH2-terminal intermediate peptide(s) with fewer than 30 amino acids. Our peptidase database search pointed out meprin-α metalloprotease as a potential candidate. Therefore, we hypothesized that, prior to POP hydrolysis, Tβ4 is hydrolyzed by meprin-α. In vitro, we found that the incubation of Tβ4 with both meprin-α and POP released Ac-SDKP, whereas no Ac-SDKP was released when Tβ4 was incubated with either meprin-α or POP alone. Incubation of Tβ4 with rat kidney homogenates significantly released Ac-SDKP, which was blocked by the meprin-α inhibitor actinonin. In addition, kidneys from meprin-α knockout (KO) mice showed significantly lower basal Ac-SDKP amount, compared with wild-type mice. Kidney homogenates from meprin-α KO mice failed to release Ac-SDKP from Tβ4. In vivo, we observed that rats treated with the ACE inhibitor captopril increased plasma concentrations of Ac-SDKP, which was inhibited by the coadministration of actinonin (vehicle, 3.1 ± 0.2 nmol/l; captopril, 15.1 ± 0.7 nmol/l; captopril + actinonin, 6.1 ± 0.3 nmol/l; P < 0.005). Similar results were obtained with urinary Ac-SDKP after actinonin treatment. We conclude that release of Ac-SDKP from Tβ4 is mediated by successive hydrolysis involving meprin-α and POP.

EFFECTS OF GROWTH HORMONE, PROLACTIN AND THYROXINE ON BODY WEIGHT, SOMATOMEDIN-LIKE ACTIVITY AND IN-VIVO SULPHATION OF CARTILAGE IN HYPOPITUITARY DWARF MICE

1980 ◽  
Vol 85 (1) ◽  
pp. 35-47 ◽  
Author(s):  
A. T. HOLDER ◽  
M. WALLIS ◽  
P. BIGGS ◽  
M. A. PREECE
Keyword(s):  
Growth Hormone ◽  
Costal Cartilage ◽  
Tail Length ◽  
Bovine Growth Hormone ◽  
Dwarf Mouse ◽  
Dwarf Mice ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
In Vivo Uptake

SUMMARY Hypopituitary dwarf mice were found to have reduced levels of serum somatomedin-like activity compared with normal mice of the Snell strain. Treatment with bovine growth hormone for 3 and 7 days resulted in growth without significantly increased levels of serum somatomedin-like activity, as detected by in-vitro uptake of 35SO42− into normal rat cartilage; only after treatment for 14 days was somatomedin activity significantly raised. However, treatment for 2 days with bovine growth hormone, bovine prolactin or thyroxine resulted in a dose-dependent increase in in-vivo uptake of 35SO42− into dwarf mouse costal cartilage; growth hormone and thyroxine did not act synergistically. Ten days of treatment with growth hormone promoted a dose-dependent increase in both growth (increased weight gain and tail length) and in-vivo uptake of 35SO42−. Increase in tail length was correlated with uptake of 35SO42−. Thus, in-vivo uptake of 35SO42− into dwarf mouse costal cartilage provides a sensitive method for detecting a dose-related effect of growth hormone.

scholarly journals Folate protects against oxidative modification of human LDL

2001 ◽  
Vol 86 (6) ◽  
pp. 637-639 ◽  
Author(s):  
Emi Nakano ◽  
John A. Higgins ◽  
Hilary J. Powers
Keyword(s):  
Lag Time ◽  
Oxidative Modification ◽  
Protective Effects ◽  
Unsaturated Lipids ◽  
Anti Oxidant ◽  
Total Homocysteine ◽  
Endogenous Antioxidants ◽  
Dose Dependent Increase ◽  
Dose Dependent

Elevated plasma total homocysteine is considered to be a graded risk factor for cardiovascular disease. Folate, through its homocysteine-lowering potential, may therefore be protective. Folate, however, may have protective effects independent of homocysteine-lowering. We have measured the effects of folate on Cu-catalysed oxidative damage to the unsaturated lipids in human LDL. Experiments were carried out in the presence of citrate, and followed increases in absorption at 234 nm, which measures the amount of conjugated diene produced. There is a lag time during which endogenous antioxidants are oxidised, followed by rapid oxidation of lipid. Addition of 0–6 μM-5-methyltetrahydrofolate produced a dose-dependent increase in the lag time, suggesting that folate may have a direct anti-oxidant role in vivo, which is independent of any indirect effects through lowering of homocysteine levels.

scholarly journals Corticosteroid effect on murine hemopoietic precursor cells in vivo

Blood ◽  
1981 ◽  
Vol 57 (6) ◽  
pp. 1138-1139 ◽  
Author(s):  
E Niskanen ◽  
J Squires
Keyword(s):  
Colony Formation ◽  
Precursor Cells ◽  
Diffusion Chambers ◽  
Hemopoietic Precursor Cells ◽  
Granulocytic Colony ◽  
Dose Dependent Increase ◽  
Dose Dependent

Abstract The effect of methylprednisolone on murine hemopoietic colony formation in diffusion chambers implanted in mice was evaluated. A dose-dependent increase in granulocytic colony (CFU-DG) formation from murine marrow was observed. This effect could be abrogated by administration of progesterone. These studies suggest that the murine early granulocytic precursors (CFU-DG) have receptors that mediate proliferation-promoting signals triggered by glucocorticoids. Erythroid colony formation (CFU- DE) was not effected by methylprednisolone administration.

scholarly journals METABOLIC ACTIVATION OF 2,6-DIMETHYLANILINE: MUTATIONAL SPECIFICITY IN THE GPT GENE OF AS52 CELLS

2018 ◽  
Vol 11 (9) ◽  
pp. 394
Author(s):  
Seo Hyun Moon ◽  
Min Young Kim
Keyword(s):  
Parent Compound ◽  
Chinese Hamster ◽  
Relative Survival ◽  
Metabolic Activation ◽  
Nested Polymerase Chain Reaction ◽  
Trypan Blue Exclusion ◽  
Polymerase Chain ◽  
Dose Dependent Increase ◽  
Dose Dependent

Objective: The purpose of the current work was to characterize the mechanisms of cytotoxicity and mutagenesis of a potential human bladder carcinogen 2,6-dimethylaniline (2,6-DMA).Methods: Chinese hamster ovary (CHO) AS52 cells were exposed to either human S9 activated 2,6-DMA for 6 h or its N-hydroxylamine and aminophenol metabolites for 1 h in serum-free medium. Cell survival was determined by trypan blue exclusion 24 h after treatment, and 6-thioguanine-resistant mutants at the xanthine-guanine phosphoribosyl transferase (gpt) gene locus were assessed with doses, of which relative survival is 30% or more. Nested polymerase chain reaction-based deletion analysis was also performed.Results: AS52 cells exhibited a dose-dependent increase in cytotoxicity and mutant fraction on treatment of 2,6-DMA and its metabolites but show a considerable variation in potency with aminophenol metabolites having the highest potency and parent compound at least; at the highest 2,6-dimethylaminophenol dose (10 μM), the mutant fraction in AS52 cells was 8-fold (13.2×10−5) greater than the spontaneous fraction of 1.62×10−5. Total deletion of the gpt gene sequences was found in 1 (4%) spontaneous and 2 (6%) the 6-thioguanine mutants generated by N-hydroxy-2,6-DMA.Conclusions: These findings indicate the mutagenicity of 2,6-DMA at the gpt gene, which is mediated through hydroxylamine and aminophenol metabolites, and contribute to the elucidation of mechanisms through which 2,6-DMA may exert its effects in vivo.

Modulation of the biological activity of thyrotrophin by anti-human thyrotrophin monoclonal antibodies

1990 ◽  
Vol 126 (2) ◽  
pp. 333-340 ◽  
Author(s):  
S. R. Page ◽  
A. H. Taylor ◽  
W. Driscoll ◽  
M. Baines ◽  
R. Thorpe ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Biological Activity ◽  
Monoclonal Antibodies ◽  
Cyclic Amp ◽  
Receptor Activation ◽  
Camp Production ◽  
Dose Dependent ◽  
Bovine Tsh

ABSTRACT The mechanism by which monoclonal antibodies enhance the biological activity of a number of hormones is poorly understood. One such antibody (GC73), which binds to human but not bovine TSH, enhances the bioactivity of human TSH in vivo. We have investigated whether GC73 enhancement of TSH bioactivity involves potentiation of hormone-receptor activation assessed by the cyclic AMP (cAMP) responses of both primary human thyrocyte cultures and a TSH-responsive human thyrocyte cell line (SGHTL-45). GC73 had no effect on basal cAMP production. In contrast to its enhancement of the bioactivity of human TSH in vivo, it markedly inhibited the cAMP response to 1 and 10 mU human TSH/ml in primary thyrocytes. This effect was dose-dependent with neutralization of the bioactivity of TSH occurring at 2 mg GC73/ml. GC73 had no effect on the bioactivity of bovine TSH. In contrast, a second anti-TSH monoclonal antibody (TC12), which binds to both human and bovine TSH, inhibited the bioactivity of both species of TSH. Similar results were obtained using SGHTL-45 cells, although the peak concentrations of cAMP were lower. We conclude that binding of GC73 to human TSH resulted in inhibition rather than enhancement of the in-vitro biological activity of human TSH. We suggest that GC73 enhancement of human TSH bioactivity seen in vivo does not result from a mechanism involving potentiation of receptor activation by human TSH. Journal of Endocrinology (1990) 126, 333–340

Dibutyryl cyclic AMP increases phosphodiesterase activity in the rat heart

1984 ◽  
Vol 62 (9) ◽  
pp. 1225-1230 ◽  
Author(s):  
Warren K. Palmer ◽  
Sylvia Doukas
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
White Muscle ◽  
Supernatant Fraction ◽  
Red Muscle ◽  
Injection Protocol ◽  
Fast Twitch ◽  
Dose Dependent ◽  
Increased Activity

The influence of increasing the in vivo concentration of cyclic AMP on the activity of cyclic nucleotide phosphodiesterase (PDE) in rat heart was investigated. One, three, and five hourly injections of 5.0 mg dibutyryl (Bt2) cyclic AMP significantly increased the activity of PDE in the supernatant fraction of rat heart using 1.0 μM cyclic AMP as the assay substrate concentration. When 100 μM cyclic AMP was used in the assay reaction, increases in enzymes activity were seen following five and eight nucleotide injections. The nucleotide-induced increase in PDE activity was dose dependent. When the five-injection protocol was used, PDE activity remained elevated for at least 4 h, while activity had returned to control levels within this time when two hourly injections were used. The nucleotide stimulation of PDE activity was blocked by cycloheximide. Five hourly infections of Bt2 cyclic AMP increased PDE activity in the liver and fast-twitch red muscle. A reduction in PDE activity in fast-twitch white muscle was seen following nucleotide injections. These findings are consistent with the hypothesis that prolonged elevations in the intracellular concentration of cyclic AMP cause an elevation in myocardial PDE activity. The increased activity seems to be the result of protein synthesis. These data suggest that cyclic AMP contributes significantly in regulating its own metabolism in the rat heart.

Sign in / Sign up

Export Citation Format

Share Document