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PubMed1984

Effects of prostaglandins on rat calvarial bone-cell calcium.

Prostaglandin E2 (PGE2) over the concentration range 10(-5)-10(-7) M stimulated calcium uptake in osteoclastic-enriched populations isolated by sequential collagenase digestions of newborn rat calvaria. This effect was on initial calcium uptake occurring at 5 min at 37 degrees C but was not present when isotopic equilibrium was approached (60 min). Prostacyclin (PGI2, PGE1 and PGF2 alpha) stimulated osteoclastic calcium uptake in a similar manner, but with slightly smaller effects than PGE2. Under identical conditions, significant effects of PG were not observed in osteoblastic cells isolated from the same bones by extended collagenase digestions. Combined treatment with PGE2 and parathyroid hormone (PTH) at concentrations which produced no individual effects resulted in a significant increase in calcium uptake in osteoclastic cells. During a 48-h culture period, osteoblastic populations released significantly greater amounts of PGE2 than osteoclastic populations. Pre-incubation for 1 h at 37 degrees C with the prostaglandin cyclo-oxygenase antagonists, indomethacin and flufenamic acid, had no effect on calcium uptake in osteoclastic cells, but resulted in significant decreases in osteoblastic cells. The PGE2-induced increase in calcium uptake on osteoclastic cells was not altered by indomethacin or flufenamic-acid pretreatment. However, after treatment with these inhibitors, a significant response to PGE2 was observed in osteoblastic cells.

Alprostadil↗
PubMed1981

Anti-inflammatory testing methods: comparative evaluation of mice and rats.

The possibility of using mice in place of rats on the anti-inflammatory screening tests was investigated. The diversities of the responses between mice and rats on screening tests, that is, carrageenin, formalin-induced edema in the hind paw, adjuvant arthritis and cotton pellet granuloma were observed with p.o. administration of prednisolone, 0.5 mg/kg and 5.0 mg/kg, and indomethacin, 0.5 mg/g and 5.0 mg/kg. On the effect of these drugs on screening tests, a similar type of phenomena between rats and mice was found. Then the close-response relationships of aspirin, flufenamic acid, phenylbutazone, cyproheptadine, prednisolone and indomethacin were examined in four kinds of screening tests mentioned above. Prednisolone, indomethacin, phenylbutazone and aspirin inhibited the carrageenin, formalin-induced edema, cotton pellet granuloma and adjuvant arthritis apparently, but flufenamic acid showed no inhibition on the carrageenin and formalin-induced edema. Cyproheptadine inhibited the formalin and serotonin-induced edema. We have found that mice, instead of rats, can be used for the anti-inflammatory screening methods.

Animals↗
PubMed2006

Swelling-activated Cl- channels support Cl- secretion by bovine ciliary epithelium.

PURPOSE: To determine whether swelling-activated Cl- currents (ICl,swell) observed in isolated nonpigmented ciliary epithelial (NPE) cells contribute to Cl- secretion across the ciliary epithelium. METHODS: Ion transport across intact bovine ciliary epithelium was monitored electrically. Native isolated bovine NPE cells were harvested enzymatically. Cell volume changes were measured by calcein-fluorescence quenching. RESULTS: Bilateral reduction in osmolality transiently increased short-circuit current (Isc), averaging 60% to 70%. Bilateral pretreatment with 5-nitro-2-(phenylpropylamino)-benzoate (NPPB), a Cl- channel blocker, reduced Isc stimulation by approximately 60%, suggesting that transcellular ICl,swell largely mediates the increased current. The hypotonically-triggered Isc stimulation was also inhibited by phloretin, a blocker of swelling-activated Cl- channels and by flufenamic acid, a blocker of Cl- and nonselective cation channels. Cyclamate substitution for bath Cl- reduced the baseline Isc and the increase in hypotonically-triggered Isc. In that case, addition of either NPPB or flufenamic acid did not produce further inhibition. The transepithelial responses were correlated with regulatory volume responses of freshly harvested NPE cells. Hypotonicity elicited a regulatory volume decrease (RVD) over a period comparable to that of the hypotonicity-triggered increase in Isc. The RVD was also inhibited by Cl--channel blockers and by Cl- substitution. CONCLUSIONS: ICl,swell of NPE cells is functionally expressed in intact ciliary epithelium and is oriented to subserve aqueous humor formation. NPE cell volume can be measured with calcein-fluorescence quenching. ICl,swell may be stimulated by increased stromal fluid uptake and delivery to the NPE cells, facilitating Cl- secretion and increasing fluid release into the posterior chamber.

Animals↗
PubMed1975

[In vitro investigations on the influence of various antirheumatic drugs on the enzymes of the purine salvage pathway (author's transl)].

On testing the effect of 5 drugs (azapropazone, flufenamic acid, indomethacin, oxyphenbutazone and prednisolone) commonly used in the therapy of rheumatic diseases on 3 enzymes of the purine salvage pathway (adenine-phosphoribosyltransferase, guanine-phosphoribosyltransferase and hypoxanthine-phosphoribosyltransferase) a distinct inhibitory effect of oxyphenbutazone and flufenamic acid was noted. A particularly marked effect was observed on adenine-phosphoribosyltransferase at the applied concentration (50 mug%) by both drugs but also guanine-phosphoribosyltransferase and hypoxanthine-phosphoribosyltransferase indicated reduced activities.

Adenine Phosphoribosyltransferase↗
PubMed1985

An ex vivo method for evaluating prostaglandin synthetase activity in cortical slices of mouse brain.

The release of prostaglandin E2 (PGE2) from cortical slices of mice into incubation medium is followed for 3 h and compared to PGE2 levels in the corresponding slice. Immediately after decapitation, the rate of PGE2 released into the incubation medium is elevated and a steady low rate of spontaneous release is gained within 1-2 h of incubation. PGE2 synthesis and release is blocked in a dose-dependent manner by either indomethacin (3 X 10(-6) -3 X 10(-4) M) or flufenamic acid (2.6 X 10(-6) M) either when added in vitro or administered in vivo. Full recovery of PGE2 synthesis is reached after 3 h incubation of slices following in vivo administration of indomethacin. In vivo administration of flufenamic acid results in prolonged inhibition of PGE2 released in vitro. The inhibition of PGE2 released by indomethacin is also correlated with the slice PGE2 content. Administration of lipopolysaccharide (LPS), a known activator of phospholipase A2, results in a fivefold increase in PGE2 and a twofold increase in 6-keto-PGF1 alpha released into the medium. The release of thromboxane B2 is not affected by LPS.

6-Ketoprostaglandin F1 alpha↗
PubMed2006

Non-steroidal anti-inflammatory drugs for heavy bleeding or pain associated with intrauterine-device use.

BACKGROUND: Heavy bleeding and pain are the most common reasons why women discontinue IUDs. Non-steroidal anti-inflammatory drugs, which inhibit prostaglandin synthesis, have been shown to be effective in reducing menstrual bleeding and pain in women without IUDs. OBJECTIVES: This review summarizes all randomized controlled trials studying use of nonsteroidal anti-inflammatory drugs for treatment of bleeding or pain associated with IUD use. Trials of prophylactic use of these drugs around the time of IUD insertion were also included. SEARCH STRATEGY: We performed searches of PubMed, CENTRAL, POPLINE, EMBASE, LILACS, and CINAHL for relevant trials. We also wrote to the authors of all trials identified to seek other published or unpublished trials. SELECTION CRITERIA: We included all randomized controlled trials in any language that tested one or more nonsteroidal anti-inflammatory drugs for treatment or prevention of bleeding or pain associated with IUD insertion or use. DATA COLLECTION AND ANALYSIS: Two authors independently abstracted data from relevant trials, and we entered data into RevMan for analysis. MAIN RESULTS: We found 15 trials from 10 countries; the total number of participants was 2702. Nonsteroidal anti-inflammatory drugs (naproxen, suprofen, mefenamic acid, ibuprofen, indomethacin, flufenamic acid, alclofenac, and diclofenac) were effective in reducing menstrual blood loss associated with IUD use. This held true for women with and without complaints of heavy bleeding. Similarly, these drugs were effective in reducing pain associated with IUD use. In contrast, prophylactic use of nonsteroidal anti-inflammatory drugs had mixed results; studies with ibuprofen found no effect on pain after insertion on IUD discontinuation. No important differences emerged in the one trial comparing the effect of different NSAIDs on bleeding. AUTHORS' CONCLUSIONS: Nonsteroidal anti-inflammatory drugs reduce bleeding and pain associated with IUD use. NSAIDs should be considered first-line therapy; if NSAIDs are ineffective, tranexamic acid may be considered as second-line therapy. Prophylactic ibuprofen administration with the first six menses after insertion appears unwarranted.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1983

Antipyretic analgesics and the allergic patient.

Recent studies of idiosyncratic reactions to analgesics have revealed several clinical patterns with different pathogeneses. In the common type of asthma precipitated by aspirin, inhibition of cyclooxygenase leads to disturbances in the metabolism of arachidonic acid. Drugs that precipitate possibly life-threatening bronchoconstriction and are absolutely contraindicated in patients with aspirin-induced asthma include indomethacin, mefenamic acid, flufenamic and meclofenamic acids, ibuprofen, fenoprofen, ketoprofen, naproxen, diclofenac, amidopyrine, noramidopyrine, phenylbutazone, flumizole, and ditazol. If necessary, patients with aspirin-induced asthma can safely take, even on a long-term basis, salicylamide, dextropropoxyphene, benzydamine, guaiacolic ester of salicylic acid, and chloroquine. In some patients with urticaria/angioedema, symptoms are due to inhibition of cyclooxygenase by analgesics; in others, the cause may be impurities in commercial preparations of aspirin; and in still others, the mechanisms remain unknown.

Acute Disease↗
PubMed2005

Gap junction channels reconstituted in two closely apposed lipid bilayers.

Intercellular communication mediated by gap junction channels plays an important role in many cellular processes. In contrast to other channels, gap junction channels span two plasma membranes resulting in an intracellular location for both ends of the junctional pore and the regulatory sites for channel gating. This configuration presents unique challenges for detailed experimental studies of junctional channel physiology and ligand-activation in situ. Availability of an appropriate model system would significantly facilitate future studies of gap junction channel function and structure. Here we show that the double-membrane channel can be reconstituted in pairs of closely apposed lipid bilayers, as experienced in cells. We have trapped the calcium-sensitive dye, arsenazo III (AIII), partially calcium-saturated (AIII-Ca), in one population of connexin32 reconstituted-liposomes, and EGTA in a second one. In such mixtures, the interaction of EGTA with AIII-Ca was measured by a large color shift from blue to red (decreased absorbance at 652 nm). The exchange of these compounds through gap junctions was proportional to these decrements. Results indicate that these connexon-mediated interliposomal channels are functional and are inhibited by the addition of alpha-glycyrrhetinic acid and by flufenamic acid, two gap junction communication inhibitors. Future use of this model system has the potential to improve our understanding of the permeability and modulation of junctional channels in its native intercellular assembly.

Arsenicals↗
PubMed2005

Blockade of chloride conductance antagonizes PMA-induced ramification in the murine microglial cell line, BV-2.

In microglial cells, activation of ion channels and ion transporters is associated with the transformation from an amoeboid to a ramified phenotype and vice versa. In the present study, we evaluated the contributions of protein kinase C (PKC) activity and ion conductance to the phorbol 12-myristate 13-acetate (PMA)-dependent ramification in the murine microglial cell line, BV-2. In a first set of experiments, we showed that PMA, a commonly used activator of PKC, but not the bioinactive analog 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), induces ramification in BV-2 cells. Surprisingly, the PKC inhibitors calphostin C, chelerythrine, or bisindolylmaleimide II did not antagonize PMA-induced ramification. In a further set of experiments, we found that 4,4'-diisocyanatostilbene-2,2' disulfonic acid (DIDS), 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS), which block chloride channels and K-Cl cotransporters, and SKF 96365, a non-selective ion channel blocker, consistently suppressed PMA-induced ramification in BV-2 cells. Additional ion channel blockers, including lanthanides, amiloride, Ba2+, 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), and flufenamic acid did not affect PMA-induced ramification in BV-2 cells. Cs+ accentuated the PMA-dependent ramification in BV-2 cells. Thus, our results indicate (1) that a PMA-binding protein, excluding PKC isoforms, is critical in structural remodeling of microglial cells and (2) that chloride conductance plays a pivotal role in induction of ramification in microglial cells.

Animals↗
PubMed1977

Stimulation of adenosine 3':5'-monophosphate formation by prostaglandins in human astrocytoma cells. Inhibition by nonsteroidal anti-inflammatory agents.

Prostaglandins (PG) of the E series and catecholamines stimulate adenosine 3':5'-monophosphate (cAMP) formation in human astrocytoma cells (1321N1). These two classes of effectors activated adenylate cyclase upon interaction with different receptor systems. No evidence for a mediatory role for PG in the action of catecholamines was found. PG interacted with 1321N1 cells with an order of potency of PGE1 = PGE2 greater than PGA1 greater than PGF2 alpha. The effect of combinations of the various PG indicated that all efficacious PG interacted with a common receptor. 7-Oxa-13-prostynoic acid and indomethacin were shown to be competitive inhibitors of the effect of PGE1 with Ki values of 4 and 150 micron, respectively. These two compounds did not inhibit the effect of isoproterenol. Polyphloretin phosphate caused a complex pattern of inhibition of the effects of PGE1 and at higher concentrations also inhibited the effects of isoproterenol. The mefenamate class of nonsteroidal anti-inflammatory agents was found to inhibit the effects of PGE1 with a potency order of meclofenamic acid greater than flufenamic acid = mefenamic acid. The inhibitory action of meclofenamic acid was complex involving specific, but partial, insurmountable antagonism of PGE1 as well as competitive inhibition of PGE1 effects. At higher concentrations of meclofenamic acid a nonspecific inhibition of the effects of both PGE1 and isoproterenol was observed. These studies suggest that the inhibition by nonsteroidal anti-inflammatory agents of the physiological effects of PGE1 in animals may occur, at least in part, at the level of adenylate cyclase. The possibility that multiple classes of adenylate cyclase-linked PGE receptors might exist in nature is discussed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1990

[Effects of oral administration of various non-steroidal anti-inflammatory drugs on bone growth and bone wound healing in mice].

Morphometric and microdensitometric studies on normal bone growth and bone wound healing in growing ICR strain male mice were carried out as preliminary investigations. Then the effects of oral administration of non-steroidal anti-inflammatory drugs on bone growth and bone wound healing were studied. Femur length and width, and bone mineral contents in the femur as judged by microdensitometry of the soft x-ray films of the cortical portion of the femur showed time-dependent linear increase between 3 and 6 weeks of age. Wound holes were made in the parietal bones of mice with a dental bar at 4 weeks of age, and uncalcified area in the holes was determined by image analysis of soft x-ray films. The area decreased their size with the advance in age, especially a marked decrease was observed 2 weeks after the operation. From the above results, 4 week-old male mice were employed and 8 kinds of non-steroidal anti-inflammatory drugs (indomethacin, 1 mg/kg; mefenamic acid, 10 mg/kg; flufenamic acid, 10 mg/kg; diclofenac sodium, 1 mg/kg; ibuprofen, 10 mg/kg; naproxen, 10 mg/kg; phenylbutazone, 10 mg/kg and aspirin, 50 mg/kg) and dexamethasone (1 mg/kg), a steroidal anti-inflammatory drugs were administered orally every day for 9 or 11 days except Sunday, and 15 days after the initial administration, the length and width of the femur were measured. The bone mineral contents were determined by microdensitometry of the soft x-ray film of the femur. Hydroxyproline contents of the femur were also determined. Wound holes were made in the parietal bones at 4 week-old and administered the drugs from one day before the operation for 9 days and the uncalcified area in the wound hole was determined 2 weeks after the operation with an image analyzer. The results obtained were as follows: 1. A significant inhibition of the growth in length of the femur was observed by dexamethasone, diclofenac sodium and naproxen administration for 9 and 11 days. A significant inhibition of the growth in width was also observed by dexamethasone and diclofenac sodium administration for 9 days and by dexamethasone administration for 11 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗
PubMed1984

Inhibition of aminoacid decarboxylases by non-steroidal antiinflammatory drugs.

Several non-steroidal antiinflammatory drugs (NSAID) were shown to inhibit to various extents the decarboxylases of ornithine, lysine, histidine, arginine, and tyrosine. The most sensitive enzyme was ornithine decarboxylase, for which piroxicam, benoxaprofen and aminophenazone showed an IC50 of 0.007 mM; ibuprofen competitively inhibits the lysine decarboxylase. The most effective NSAID's in inhibiting histidine decarboxylase were mefenamic acid, ibuprofen and flufenamic acid. Arginine and tyrosine decarboxylase were inhibited by NSAID's only at high concentrations. None of the decarboxylase inhibitions were reversed by pyridoxal phosphate. Subplantar injection of the 5 amines formed by these aminoacid decarboxylases elicited a paw oedema in rat which was not antagonized by the various NSAID's. Some of the NSAID's stimulated all the decarboxylases and did not antagonize the carrageenin-induced paw oedema. With one exception, all the NSAID's tested in vivo inhibited the elimination of 14CO2 from labeled ornithine and lysine. The inhibition of certain aminoacid decarboxylases, particularly ornithine and lysine decarboxylase, appears to be a noteworthy mechanism of action for certain NSAID's.

Animals↗
PubMed2005

Thiol-containing molecules interact with the myeloperoxidase/H2O2/chloride system to inhibit LDL oxidation.

Oxidized low-density lipoproteins (LDL) accumulate in the vascular wall and promote a local inflammatory process contributing to the progression of atheromatous plaque. The key role of myeloperoxidase (MPO) in this process has been documented and the enzyme has been involved in the oxidative modification of apolipoprotein B-100 in the intima and at the surface of endothelial cells. As the inhibition of this last phenomenon could be of relevance in pharmacological interventions, thiol-containing molecules such as glutathione, captopril, and N-acetylcysteine (NAC) and its lysinate salt (NAL) were tested in this system and their properties were compared with those of flufenamic acid (control). This last compound already demonstrated an inhibition of the production of HOCl by MPO and a more intense inhibition of MPO activity than glutathione, NAC, NAL, and captopril. However, NAC and NAL inhibited the oxidative modification of LDL more intensively than captopril and glutathione whereas flufenamic acid had no comparable inhibiting effect. This could be related to the presence of LDL close to the catalytic site of the enzyme. NAC and NAL therefore appeared as the most efficient inhibitors probably as a consequence of their relatively small size. The relevance of such effects has to be documented by in vivo studies.

Acetylcysteine↗
PubMed1975

A sensitive method for the comparative bioassay of nonsteroidal anti-inflammatory compounds in adjuvant-induced primary inflammation in the rat.

A method for the comparative bioassay of nonsteroidal anti-inflammatory agents is presented which exploits the early inflammation induced by injection of adjuvant into the plantar surface of a hind paw of the rat. The inflammation reaches a peak on the 4th postinjection day. Daily treatment with nonsteroidal anti-inflammatory agents reduces paw volumes and the associated impairment of body growth with optimal improvement on the 4th postinjection day. In this model, phenylbutazone has shown significant activity at doses as low at 1.33 mg/kg/day. Statistically valid comparative assays conducted at dose levels equivalent to or below those used in human therapy yield potency ratios with relatively narrow confidence limits. Potencies relative to phenylbutazone for inhibiting primary adjuvant-induced inflammation are: aminopyrine, 0.066 (0.36-0.11)95%; aspirin, 0.087 (0.039-0.19)95%; mefenamic acid, 0.98 (0.64-1.6)95%; flufenamic acid, 13 (7.4-26)95%; meclofenamic acid, 23(16-33)95%; and indomethacin, 53 (35-82) 95%. Ancillary and sometimes quantitative information is also provided by the improvement in well being of the animals as reflected in body weight changes with treatment.

Aminopyrine↗
PubMed2004

Comparison of four different in vitro systems to study the reservoir capacity of the stratum corneum.

Four in vitro test systems were used to study the reservoir capacity of porcine stratum corneum (SC) for flufenamic acid and its drainage via penetration into the deeper skin layers: Franz diffusion cell using full thickness skin and split skin of 300 mum; Saarbruecken penetration model (SB) and intact porcine tissue (IP). Each skin sample was segmented 1, 4 and 21 h after application of an 'infinite dose' of flufenamic acid. The lipophilic drug was extracted from the SC and the deeper skin layers (viable epidermis and dermis) and determined using high-performance liquid chromatography (HPLC). For each test system, an increase in the drug amount in the deeper skin layers and the acceptor fluid, respectively, was observed in combination with a decreased amount in the SC with increasing time after application. The drainage of the SC reservoir was only reflected by a linear correlation of the drug amount in the SC with the amount in the deeper skin layers in the case of IP. The absolute drug concentrations previously detected in human skin in vivo and in vitro were compared with the present data, affording the best accordance in the case of IP.

Animals↗
PubMed2003

Non-steroidal anti-inflammatory drugs affect the methotrexate transport in IEC-6 cells.

Methotrexate (MTX) is used not only for the cancer chemotherapy but also for the treatment of rheumatic disease, often together with non-steroidal anti-inflammatory drugs (NSAIDs). MTX is actively cotransported with H(+) in the small intestine, mediated by a reduced folate carrier (RFC). The coadministration of some NSAIDs with MTX to rats caused a decrease of MTX absorption through the small intestine. This may be due to the uncoupling effect of oxidative phosphorylation of the NSAIDs. The present study investigated whether flufenamic acid, diclofenac and indomethacin, NSAIDs, decreased ATP content of rat-derived intestinal epithelial cell line IEC-6 cells and affected the MTX transport in IEC-6 cells. The MTX uptake in IEC-6 cells was dependent on medium pH and maximum around pH 4.5-5.5. The MTX uptake was composed of a transport inhibited by 4, 4'-diisothiocyanostilbene-2, 2'-disulfonic acid (DIDS) and a non-saturable one. The DIDS-sensitive component in the MTX uptake showed a saturation kinetics (Michaelis-Menten constant (Km): 3.91 +/- 0.52 microM, Maximum velocity (Vmax): 94.66 +/- 6.56 pmol/mg protein/5 min). The cellular ATP content in IEC-6 cells decreased significantly at 30 min after the cells were started to incubate with the NSAIDs (250 microM flufenamic acid, 500 microM diclofenac and 500 microM indomethacin). The MTX uptake in IEC-6 cells in the presence of the NSAIDs decreased with the reduction of cellular ATP content and showed a good correlation with the ATP content (correlation coefficient: 0.982). Thus it seems likely that the ATP content in IEC-6 cells with the NSAIDs decreased due to the uncoupling effect of oxidative phosphorylation of the NSAIDs, resulting in the inhibition of the secondary active transport of MTX in IEC-6 cells. The present results also suggest that IEC-6 cells are useful to evaluate the drug interaction relating to this carrier system.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2003

Epigallocatechin-3-gallate increases intracellular [Ca2+] in U87 cells mainly by influx of extracellular Ca2+ and partly by release of intracellular stores.

Green tea has been receiving considerable attention as a possible preventive agent against cancer and cardiovascular disease. Epigallocatechin-3-gallate (EGCG) is a major polyphenol component of green tea. Using digital calcium imaging and an assay for [3H]-inositol phosphates, we determined whether EGCG increases intracellular [Ca2+] ([Ca2+]i) in non-excitable human astrocytoma U87 cells. EGCG induced concentration-dependent increases in [Ca2+]i. The EGCG-induced [Ca2+]i increases were reduced to 20.9% of control by removal of extracellular Ca2+. The increases were also inhibited markedly by treatment with the non-specific Ca2+ channel inhibitors cobalt (3 mM) for 3 min and lanthanum (1 mM) for 5 min. The increases were not significantly inhibited by treatment for 10 min with the L-type Ca2+ channel blocker nifedipine (100 nM). Treatment with the inhibitor of endoplasmic reticulum Ca2+-ATPase thapsigargin (1 micro M) also significantly inhibited the EGCG-induced [Ca2+]i increases. Treatment for 15 min with the phospholipase C (PLC) inhibitor neomycin (300 micro M) attenuated the increases significantly, while the tyrosine kinase inhibitor genistein (30 micro M) had no effect. EGCG increased [3H]-inositol phosphates formation via PLC activation. Treatment for 10 min with mefenamic acid (100 micro M) and flufenamic acid (100 micro M), derivatives of diphenylamine-2-carboxylate, blocked the EGCG-induced [Ca2+]i increase in non-treated and thapsigargin-treated cells but indomethacin (100 micro M) did not affect the increases. Collectively, these data suggest that EGCG increases [Ca2+]i in non-excitable U87 cells mainly by eliciting influx of extracellular Ca2+ and partly by mobilizing intracellular Ca2+ stores by PLC activation. The EGCG-induced [Ca2+]i influx is mediated mainly through channels sensitive to diphenylamine-2-carboxylate derivatives.

Calcium↗
PubMed2006

Endogenous hemichannels play a role in the release of ATP from Xenopus oocytes.

ATP is an electrically charged molecule that functions both in the supply of energy necessary for cellular activity and as an intercellular signaling molecule. Although controlled ATP secretion occurs via exocytosis of granules and vesicles, in some cells, and under certain conditions, other mechanisms control ATP release. Gap junctions, intercellular channels formed by connexins that link the cytoplasm of two adjacent cells, control the passage of ions and molecules up to 1 kDa. The channel is formed by two moieties called hemichannels, or connexons, and it has been suggested that these may represent an alternative pathway for ATP release. We have investigated the release of ATP through hemichannels from Xenopus oocytes that are formed by Connexin 38 (Cx38), an endogenous, specific type of connexin. These hemichannels generate an inward current that is reversibly activated by calcium-free solution and inhibited by octanol and flufenamic acid. This calcium-sensitive current depends on Cx38 expression: it is decreased in oocytes injected with an antisense oligonucleotide against Cx38 mRNA (ASCx38) and is increased in oocytes overexpressing Cx38. Moreover, the activation of these endogenous connexons also allows transfer of Lucifer Yellow. We have found that the release of ATP is coincident with the opening of hemichannels: it is calcium-sensitive, is inhibited by octanol and flufenamic acid, is inhibited in ASCx38 injected oocytes, and is increased by overexpression of Cx38. Taken together, our results suggest that ATP is released through activated hemichannels in Xenopus oocytes.

Adenosine Triphosphate↗