Effects of glucocorticoids on prostaglandin formation by human amnion

1990 ◽  
Vol 68 (6) ◽  
pp. 671-676 ◽  
Author(s):  
William Gibb ◽  
Jean-Claude Lavoie
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Isolated Cells ◽  
Stimulatory Action ◽  
Human Amnion ◽  
Human Labor ◽  
Epidermal Growth

The human amnion may be an important source of prostaglandins involved in the onset of human labor and therefore it is important to define the factors that regulate their formation in this tissue. In the present study we demonstrate that glucocorticoids inhibit prostaglandin production by freshly isolated amnion cells. The inhibitory action of the glucocorticoids, however, changes to a stimulatory action when the cells are maintained in primary culture for a few days. For both inhibition and stimulation, concentrations of 10−8 M dexamethasone or greater were required to give significant effects, and estradiol and progesterone had no effect on the prostaglandin output of the cells. Epidermal growth factor (EGF), which has previously been found to stimulate prostaglandin output by confluent amnion cells, did not alter prostaglandin output of cells initially placed in culture. Furthermore, the stimulatory action of EGF and dexamethasone appeared additive. The calcium ionophore A23187 stimulated prostaglandin output in freshly isolated cells and accentuated the inhibitory effect of dexamethasone. These studies indicate that prostaglandin formation by human amnion during pregnancy could be regulated by glucocorticoids. These steroids are easily available to the amnion by way of cortisone conversion to Cortisol by the maternal decidua. The results also indicate that amnion is capable of responding to glucocorticoids in both a stimulatory and inhibitory fashion and whether one or both actions are of importance in vivo is a question that is as yet unresolved.Key words: prostaglandins, amnion, fetal membranes, glucocorticoids, labor, pregnancy.

Singlet oxygen scavengers affect laser-dye impairment of endothelium-dependent responses of brain arterioles

1996 ◽  
Vol 270 (4) ◽  
pp. H1258-H1263 ◽  
Author(s):  
W. I. Rosenblum ◽  
G. H. Nelson
Keyword(s):  
Singlet Oxygen ◽  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Protective Effects ◽  
Laser Dye ◽  
Oxygen Scavengers ◽  
Heat Injury

This study investigates the possible role of singlet oxygen in accounting for the inhibitory effect of laser-dye injury on endothelium-dependent dilations. The combination of helium-neon (HeNe) laser (20-s exposure) and intravascular Evans blue impairs endothelium-dependent dilation of mouse pial arterioles by acetylcholine (ACh), bradykinin (BK), and calcium ionophore A23187. Each has a different endothelium-derived mediator (EDRFACh, EDRFBK, EDRFionophore, respectively). In this study, diameters at a craniotomy site were monitored in vivo with an image splitter-television microscope. The laser-dye injury, as usual, abolished the responses 10 and 30 min after injury, with recovery, complete or partial, at 60 min. Dilations by sodium nitroprusside, an endothelium-independent dilator, were not affected by laser-dye. When the singlet oxygen scavengers L-histidine (10(-3) M) and L-tryptophan (10(-2) M) were added to the suffusate over the site, the responses to ACh at 10 and 30 min were relatively intact, the response to BK was partly protected at 10 min only, and the response to ionophore was still totally impaired at 10 and 30 min. Lysine, a nonscavenging amino acid, had no protective effects with any dilator. We postulate that a heat-induced injury initiates a chain of events resulting in prolonged singlet oxygen generation by the endothelial cell (not by the dye). We postulate further that destruction of EDRFACh by singlet oxygen is responsible for laser-dye inhibition of ACh and that generation of the radical must continue for > or = 30 min. On the other hand, the heat injury itself is probably responsible for the elimination of the response to ionophore. Heat plus singlet oxygen generated by heat-damaged tissue may initially impair the response to BK, but by 30 min only the effects of some other factor, presumably heat injury, account for the impaired response to BK.

scholarly journals Tulathromycin Exerts Proresolving Effects in Bovine Neutrophils by Inhibiting Phospholipases and Altering Leukotriene B4, Prostaglandin E2, and Lipoxin A4Production

2014 ◽  
Vol 58 (8) ◽  
pp. 4298-4307 ◽  
Author(s):  
Carrie D. Fischer ◽  
Stephanie C. Duquette ◽  
Bernard S. Renaux ◽  
Troy D. Feener ◽  
Douglas W. Morck ◽  
...  
Keyword(s):  
Calcium Ionophore ◽  
Leukotriene B4 ◽  
Calcium Ionophore A23187 ◽  
Lipid Signaling ◽  
Prostaglandin E ◽  
Ionophore A23187 ◽  
Proinflammatory Mediators ◽  
Bovine Neutrophils

ABSTRACTThe accumulation of neutrophils and proinflammatory mediators, such as leukotriene B4(LTB4), is a classic marker of inflammatory disease. The clearance of apoptotic neutrophils, inhibition of proinflammatory signaling, and production of proresolving lipids (including lipoxins, such as lipoxin A4[LXA4]) are imperative for resolving inflammation. Tulathromycin (TUL), a macrolide used to treat bovine respiratory disease, confers immunomodulatory benefits via mechanisms that remain unclear. We recently reported the anti-inflammatory properties of TUL in bovine phagocytesin vitroand inMannheimia haemolytica-challenged calves. The findings demonstrated that this system offers a powerful model for investigating novel mechanisms of pharmacological immunomodulation. In the present study, we examined the effects of TUL in a nonbacterial model of pulmonary inflammationin vivoand characterized its effects on lipid signaling. In bronchoalveolar lavage (BAL) fluid samples from calves challenged with zymosan particles (50 mg), treatment with TUL (2.5 mg/kg of body weight) significantly reduced pulmonary levels of LTB4and prostaglandin E2(PGE2). In calcium ionophore (A23187)-stimulated bovine neutrophils, TUL inhibited phospholipase D (PLD), cytosolic phospholipase A2(PLA2) activity, and the release of LTB4. In contrast, TUL promoted the secretion of LXA4in resting and A23187-stimulated neutrophils, while levels of its precursor, 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], were significantly lower. These findings indicate that TUL directly modulates lipid signaling by inhibiting the production of proinflammatory eicosanoids and promoting the production of proresolving lipoxins.

Calcium-translocating and cardiotonic properties of oxidation products of linoleic acid

1985 ◽  
Vol 63 (11) ◽  
pp. 1392-1397 ◽  
Author(s):  
Ryungsoon Song Kim ◽  
Ivan Bihler ◽  
Frank S. LaBella
Keyword(s):  
Linoleic Acid ◽  
Calcium Ionophore ◽  
Physiological Role ◽  
Calcium Ionophore A23187 ◽  
Oxidation Products ◽  
Ionophore A23187 ◽  
Guinea Pig Heart ◽  
Adrenergic Antagonist

Calcium-translocating activity of linoleic acid and its lipoxygenase (linoleate: oxygen oxidoreductase; EC 1.13.11.12) metabolites or autoxidation products was determined in vitro by estimation of 45Ca transport from a bulk aqueous to a bulk organic phase. Fresh commercial linoleic acid, tested immediately after removal from a sealed vial, stimulated calcium translocation only at concentrations greater than 1 mM. In contrast, 45Ca translocation by linoleic acid exposed to air was detectable at 10 μM. Oxidation products of linoleic acid obtained either by incubation with lipoxygenase or by autoxidation were much less potent than the calcium ionophore A23187. The products obtained by enzymic oxidation of linoleic acid enhanced contractility in the Langendorff-perfused guinea pig heart up to 45% over control (at 3 × 10−8 M). The inotropic response was transient with rapid onset and not affected by the beta-adrenergic antagonist, propranolol. The autoxidation products of linoleic acid increased cardiac contractility up to 43% at 10−6 M. In contrast, fresh linoleic acid caused only a negative inotropic effect at 10−8 to 3 × 10−7 M, progressing to contracture at 10−6 M. These findings suggest that conflicting reports on the cardiostimulant effect of linoleic acid may be due to varying levels of the autoxidation products. Linoleic acid metabolites in vivo may have a physiological role in myocardial function related to their Ca2+-ionophoric activity.

L-arginine restores endothelium-dependent relaxation in pulmonary circulation of chronically hypoxic rats

1992 ◽  
Vol 263 (2) ◽  
pp. L194-L200 ◽  
Author(s):  
S. Eddahibi ◽  
S. Adnot ◽  
C. Carville ◽  
Y. Blouquit ◽  
B. Raffestin
Keyword(s):  
Vascular Tone ◽  
Pressor Response ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Relaxing Factor ◽  
Isolated Lungs ◽  
Endothelium Dependent Relaxation

We investigated whether loss of endothelial-derived relaxing factor (EDRF) activity in the pulmonary vessels of chronically hypoxic rats could be restored by pretreatment with L-arginine. We measured vasodilation to acetylcholine (ACh), calcium ionophore A23187, or linsidomine (Sin-1) under conditions of increased vascular tone induced by U-46619 (50 pmol/min), as well as vasoconstriction to endothelin-1 (ET) in isolated lungs pretreated with meclofenamate (3 microM). In lungs from normoxic (N) rats, in vitro L- or D-arginine (10(-3) M) did not alter vasodilation to the endothelium-dependent agents ACh (10(-9)-10(-6) M) and A23187 (10(-9)-10(-7) M), but NG-monomethyl-L-arginine (10(-3) M) completely abolished it. In lungs from rats exposed to 3 wk of hypoxia (H), vasodilation to ACh or A23187 was fully restored after in vitro L-arginine (10(-3) M) or N alpha-benzoyl-L-arginine (5 x 10(-5) M) but remained abolished after D-arginine, L-citrulline, L-ornithine, or L-argininosuccinic acid. In vivo pretreatment of H rats with L-arginine (300 mg/kg iv) 30 min before isolating the lung also restored vasodilation to A23187. Vasodilation to the endothelium-independent agent Sin-1 was similar in both groups of lungs and was not altered by in vitro L-arginine. L-arginine attenuated the increased pressor response to ET (300 pmol) of H rat lungs but had no effect in N rats. Our results demonstrate that loss of EDRF activity associated with hypoxic pulmonary hypertension may be reversed by supplying L-arginine.

scholarly journals A neurotransmitter role for red-pigment-concentrating hormone in ovarian maturation in the red swamp crayfish Procambarus clarkii

1995 ◽  
Vol 198 (6) ◽  
pp. 1253-1257 ◽  
Author(s):  
R Sarojini ◽  
R Nagabhushanam ◽  
M Fingerman
Keyword(s):  
Procambarus Clarkii ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Ovarian Maturation ◽  
Red Pigment ◽  
In Vitro Techniques ◽  
Red Swamp Crayfish

The influence of red-pigment-concentrating hormone (RPCH) on ovarian maturation in the red swamp crayfish Procambarus clarkii was studied using both in vivo and in vitro techniques. In vivo, RPCH stimulated ovarian maturation. However, RPCH did not affect the ovary in vitro when only RPCH, muscle and ovarian explants were used. But when RPCH, thoracic ganglia, which are known to contain gonad-stimulating hormone-like (GSH-like) activity, and ovarian explants were incubated together, significant ovarian maturation ensued. The calcium ionophore A23187 mimicked RPCH both in vivo and in vitro. These results provide evidence to support the hypothesis that RPCH has a role as a neurotransmitter in Procambarus clarkii to stimulate GSH release, with calcium acting as a second messenger for RPCH.

Calcium modulates vasopressin effect in rabbit cortical collecting tubule

1987 ◽  
Vol 252 (1) ◽  
pp. F115-F121 ◽  
Author(s):  
M. A. Dillingham ◽  
B. S. Dixon ◽  
R. J. Anderson
Keyword(s):  
Calcium Uptake ◽  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calcium Activity ◽  
Cellular Calcium ◽  
Collecting Tubules ◽  
Bathing Fluid

The calcium ion has been proposed to be an important mediator of the hydroosmotic response to arginine vasopressin (AVP). We examined the effect of reducing basolateral calcium activity on hydraulic conductivity (Lp) in response to AVP in rabbit cortical collecting tubules (CCT) perfused in vitro. Each tubule served as its own control. Reducing bathing fluid calcium from 0.94 mM to 4.6 microM reduced Lp in each tubule (mean decrease from 146 +/- 13 to 106 +/- 7 cm X s-1 X atm X 10(-7), n = 11, P less than 0.025). To determine whether this inhibitory effect was due to a decrease in cellular calcium uptake, we measured the effect of adding 10(-4) M lanthanum to bathing fluid on AVP-stimulated Lp. Lanthanum decreased Lp (from 109 +/- 13 to 80 +/- 10 cm X s-1 X atm X 10(-7), P less than 0.05) in each tubule. To examine the site at which low peritubular calcium activity regulates AVP action, we measured the effect of decreasing bathing fluid calcium on 8-[p-chlorophenylthio]-adenosine 3',5'-cyclic monophosphate (ClPheS-cAMP)-stimulated Lp (n = 5). Decreasing bathing fluid calcium significantly decreases (P less than 0.025) Lp response to ClPheS-cAMP. Since these results suggest that cellular calcium uptake can exert a post-cAMP effect to modulate AVP action, we examined the effect of the calcium ionophore A23187 (10(-7) M) on AVP- and ClPheS-cAMP-stimulated Lp A23187 reversibly potentiates (25-30%, P less than 0.025) the Lp response to both AVP and ClPheS-cAMP.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effects of calcium ionophore pretreatment of porcine oocytes on polyspermic fertilization

Zygote ◽  
2006 ◽  
Vol 14 (1) ◽  
pp. 17-22 ◽  
Author(s):  
T. Hayashi ◽  
H. Sato ◽  
H. Iwata ◽  
T. Kuwayama ◽  
Y. Monji
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
The Other ◽  
Ionophore A23187 ◽  
Inhibitory Effects ◽  
High Concentration ◽  
Maturation Period ◽  
Low Concentration ◽  
Other Hand

The present study examined the inhibitory effects of various pretreatment concentrations (0–100 μM) of the calcium ionophore A23187 on polyspermic fertilization and then examined the effect of the maturation period and the time between calcium ionophore treatment and fertilization on the inhibitory effect of calcium ionophore on polyspermic fertilization. In experiment 1, a high concentration of calcium ionophore (100 μM) increased the rate of activated oocytes, but the rate of fertilization declined. On the other hand, when oocytes were treated with a low concentration of calcium ionophore (10 μM), monospermic fertilization was significantly increased (10 μM; 31.3%) (p < 0.05). In experiment 2, oocytes were cultured for various times (0, 0.5, 3, 6 h) after calcium ionophore treatment (10 μM) before fertilization. The highest rate of monospermic fertilization was detected in the oocytes cultured for 6 h after calcium ionophore treatment before fertilization. In experiments 3 and 4, we examined the effect of the maturation period (40 h or 44 h) on the rate of fertilization and blastulation of oocytes pretreated with calcium ionophore. The treatment of oocytes with calcium ionophore significantly decreased the rate of polyspermic fertilization regardless of the maturation period (44 h: with calcium ionophore 26.25% vs without 78.8%; 40 h: with calcium ionophore 37.5% vs without 77.5%); however, calcium ionophore treatment increased the rates of monospermic fertilization and blastulation of the oocytes matured for 44 h, but not those matured for 40 h. In conclusion, activation with a low concentration of calcium ionophore (10 μM) and a further 6 h of culture before fertilization improved the rate of monospermic fertilization and blastulation.

scholarly journals Inhibitory effect of LY 255283 on the synthesis of leukotriene B4and thromboxane A2in human peripheral blood polymorphonuclear leukocytes and monocytes

1993 ◽  
Vol 2 (6) ◽  
pp. 407-409 ◽  
Author(s):  
M. Ugur ◽  
M. Melli
Keyword(s):  
Receptor Antagonist ◽  
Peripheral Blood ◽  
Polymorphonuclear Leukocytes ◽  
Human Peripheral Blood ◽  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Human Monocytes

LY 255283 [(1-(5-ethyl-2-hydroxy-4-(6-methyl-6-)1H-tetrazol-5-yl)-heptyloxy) phenyl)ethanone], a specific leukotriene B4(LTB4) receptor antagonist, inhibited the production of LTB4in human peripheral blood polymorphonuclear leukocytes (PMNL) and in monocytes activated by calcium ionophore A23187. In human monocytes activated by ionophore it inhibited also the production of thromboxane B2(TXB2). The effect of LY 255283 on 5-lipoxygenase (5-LO) and LTA4hydrolase activities which catalyse the production of LTB4and LTA4has not been studied yet. It is thought that LY 255283 may inhibit the production of LTB4and TXA2by antagonising the effect of ionophore-induced LTB4on 5-lipoxygenase and cyclooxygenase in human peripheral blood PMNL and monocytes.

Heparin inhibits histamine release from canine mast cells

1993 ◽  
Vol 264 (4) ◽  
pp. L387-L390 ◽  
Author(s):  
N. Inase ◽  
R. E. Schreck ◽  
S. C. Lazarus
Keyword(s):  
Mast Cells ◽  
Charge Density ◽  
Histamine Release ◽  
Negative Charge ◽  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Similar Inhibitory Effect ◽  
Negative Charge Density

To determine the role of heparin in mast cell exocytosis, we studied the effect of heparin on histamine release induced by compound 48/80 or calcium ionophore A23187 in canine mastocytoma cells (BR). Heparin caused concentration-dependent inhibition of compound 48/80-induced histamine release from mast cells (n = 4; P < 0.05) with a mean inhibitory concentration of 0.14 +/- 0.01 U/ml (mean +/- SE). Mean maximal inhibition was 69.3 +/- 2.0%. In contrast, heparin had no effect on calcium ionophore A23187-induced histamine release. Although benzyl alcohol, a preservative of pharmaceutical heparin, had no effect, purified heparin produced a similar inhibitory effect on compound 48/80-induced histamine release (n = 4; P < 0.05). The inhibitory effect of heparin on histamine release was rapid and was eliminated by washing cells. Dextran sulfate, a polysaccharide with negative charge density, produced a similar inhibitory effect on compound 48/80-induced histamine release (n = 4; P < 0.05). We conclude that heparin inhibits compound 48/80-induced exocytosis in mast cells probably by its negative charge density.

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