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Hong-Tai Chang

Publications and source records attributed to Hong-Tai Chang.

At least 37 records · Page 2Linked to original sources
PubMed2004

Synthesis of phthalide derivatives using nickel-catalyzed cyclization of o-haloesters with aldehydes.

The reaction of o-bromobenzoate (1 b) with benzaldehyde (2 a) in the presence of [NiBr(2)(dppe)] (dppe=1,2-bis(diphenylphosphino)ethane) and zinc powder in THF (24 hours, reflux temperature), afforded 3-phenyl-3H-isobenzofuran-1-one (3 a) in an 86 % yield. Similarly, o-iodobenzoate reacts with 2 a to give 3 a, but in a lower yield (50 %). A series of substituted aromatic and aliphatic aldehydes (2 b, 4-MeC(6)H(4)CHO; 2 c, 4-MeOC(6)H(4)CHO; 2 d, 3-MeOC(6)H(4)CHO; 2 e, 2-MeOC(6)H(4)CHO; 2 f, 4-CNC(6)H(4)CHO; 2 g, 4-(Me)(3)CC(6)H(4)CHO; 2 h, 4-C(6)H(5)C(6)H(4)CHO; 2 i, 4-ClC(6)H(4)CHO; 2 j, 4-CF(3)C(6)H(4)CHO; 2 k, CH(3)(CH(2))(5)CHO; 2 l, CH(3)(CH(2))(2)CHO) also underwent cyclization with o-bromobenzoate (1 b) producing the corresponding phthalide derivatives in moderate to excellent yields and with high chemoselectivity. Like 1 b, methyl 2-bromo-4,5-dimethoxybenzoate (1 c) reacts with tolualdehyde (2 b) to give the corresponding substituted phthalide 3 m in a 71 % yield. The methodology can be further applied to the synthesis of six-membered lactones. The reaction of methyl 2-(2-bromophenyl)acetate (1 d) with benzaldehyde under similar reaction conditions afforded six-membered lactone 3 o in a 68 % yield. A possible catalytic mechanism for this cyclization is also proposed.

Journal Article↗
PubMed2004

Effect of the antidepressant maprotiline on calcium movement and the viability of renal tubular cells.

In Madin-Darby canine kidney (MDCK) cells, the effect of maprotiline, an antidepressant, on intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2. Maprotiline (> 2.5 microM) caused a rapid rise of [Ca(2+)](i) in a concentration-dependent manner (EC(50) 200 microM). Maprotiline-induced [Ca(2+)](i) rise was reduced by removal of extracellular Ca(2+) or by addition of La(3+), but was not altered by voltage-gated Ca(2+)-channel blockers. Maprotiline-induced Mn(2+) influx-associated fura-2 fluorescence quench directly suggests that maprotiline caused Ca(2+) influx. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which the increasing effect of maprotiline on [Ca(2+)](i) was nearly abolished; also, pretreatment with maprotiline reduced a portion of thapsigargin-induced [Ca(2+)](i) rise. U73122, an inhibitor of phospholipase C, abolished [Ca(2+)](i) rise induced by ATP (but not by maprotiline). Overnight incubation with 1-10 microM maprotiline enhanced cell viability, but 20-50 microM maprotiline decreased it. These findings suggest that maprotiline rapidly increases [Ca(2+)](i) in renal tubular cells by stimulating both extracellular Ca(2+) influx and intracellular Ca(2+) release, and may modulate cell proliferation in a concentration-dependent manner.

Animals↗
PubMed2004

Effect of the antidepressant maprotiline on Ca2+ movement and proliferation in human prostate cancer cells.

1. The effect of maprotiline, an antidepressant, on human prostate cells is unclear. In the present study, the effect of maprotiline on [Ca2+]i and growth in PC3 human prostate cancer cells was measured using the fluorescent dyes fura-2 and tetrazolium, respectively. 2. Maprotiline caused a rapid, concentration-dependent increase in [Ca2+]i (EC50 = 200 micromol/L). The maprotiline-induced [Ca2+]i increase was reduced by removal of extracellular Ca2+ or pretreatment with nicardipine. 3. The maprotiline-induced Mn2+ influx-associated fura-2 fluorescence quench directly suggests that maprotiline caused Ca2+ influx. 4. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca2+]i increase, after which the effects of maprotiline of increasing [Ca2+]i were abolished. In addition, pretreatment with maprotiline reduced a major portion of the thapsigargin-induced increase in [Ca2+]i. 5. U73122, an inhibitor of phospholipase C, abolished the ATP (but not maprotiline)-induced increase in [Ca2+]i. 6. Overnight incubation with 1-10 micromol/L maprotiline did not alter cell proliferation, although incubation with 30-50 micromol/L maprotiline decreased cell proliferation. 7, These findings suggest that maprotiline rapidly increases [Ca2+]i in human prostate cancer cells by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release and that it may modulate cell proliferation in a concentration-dependent manner.

Antidepressive Agents, Second-Generation↗
PubMed2004

Effect of calmidazolium on Ca(+2) movement and proliferation in human osteosarcoma cells.

In human MG63 osteosarcoma cells, the effect of calmidazolium on [Ca(2+)](i) and proliferation was explored using fura-2 and ELISA, respectively. Calmidazolium, at concentrations greater than 0.1 micromol/L, caused a rapid increase in [Ca(2+)](i) in a concentration-dependent manner (EC(50) = 0.5 micromol/L). The calmidazolium-induced [Ca(2+)](i) increase was reduced by 66% by removal of extracellular Ca(2+). In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic increase in [Ca(2+)](i), after which the effect of calmidazolium to increase [Ca(2+)](i) was completely inhibited. U73122, an inhibitor of phospholipase C (PLC), abolished histamine (but not calmidazolium)-induced increases in [Ca(2+)](i). Pretreatment with phorbol 12-myristate 13-acetate to activate protein kinase C inhibited the calmidazolium-induced increase in [Ca(2+)](i) in Ca(2+)-containing medium by 47%. Separately, it was found that overnight treatment with 2-10 micromol/L calmidazolium inhibited cell proliferation in a concentration-dependent manner. These results suggest that calmidazolium increases [Ca(2+)](i) by stimulating extracellular Ca(2+) influx and also by causing release of intracellular Ca(2+) from the endoplasmic reticulum in a PLC-independent manner. Calmidazolium may be cytotoxic to osteosarcoma cells.

Bone Neoplasms↗
PubMed2004

Effect of nortriptyline on intracellular Ca2+ handling and proliferation in human osteosarcoma cells.

The effect of the antidepressant nortriptyline, on bone cells is unknown. In human osteosarcoma MG63 cells, the effect of nortriptyline on intracellular Ca2+ concentration ([Ca2+]i) and proliferation was measured by using fura-2 and tetrazolium, respectively. Nortriptyline (> or = 10 microM) caused a [Ca2+]i rise in a concentration-dependent manner (EC50 = 200 microM). Nortriptyline-induced [Ca2+]i rise was prevented by 60% by removal of extracellular Ca2+ but was not altered by voltage-gated Ca2+ channel blockers. In Ca2+ -free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ -ATPase, caused a monophasic [Ca2+]i rise, after which the increasing effect of nortriptyline on [Ca2+]i was abolished; also, pretreatment with nortriptyline abolished thapsigargin-induced [Ca2+]i increase. U73122, an inhibitor of phospholipase C, did not affect nortriptyline-induced [Ca2+]i rise; however, activation of protein kinase C decrease nortriptyline-induced [Ca2+]i rise by 32%. Overnight incubation with 50 and 100 microM nortriptyline killed 78% and 97% of cells, respectively; while 10 microM nortriptyline had no effect. These data suggest that nortriptyline rapidly increases [Ca2+]i in human osteosarcoma cells by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release, and is cytotoxic at high concentrations.

Antidepressive Agents, Tricyclic↗
PubMed2003

Effect of diethylstilbestrol on Ca2+ handling and cell viability in human breast cancer cells.

In human breast cancer cells, the effect of the widely prescribed estrogen diethylstilbestrol (DES) on intracellular Ca2+ concentrations ([Ca2+]i) and cell viability was explored by using fura-2 and trypan blue exclusion, respectively. DES caused a rise in [Ca2+]i in a concentration-dependent manner (EC50 = 15 microM). DES-induced [Ca2+]i rise was reduced by 80 % by removal of extracellular Ca2+. DES-induced Mn(2+)-associated quench of intracellular fura-2 fluorescence also suggests that DES induced extracellular Ca2+ influx. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a monophasic [Ca2+]i rise, after which the increasing effect of DES on [Ca2+]i was greatly inhibited. Conversely, pretreatment with DES to deplete intracellular Ca2+ stores totally prevented thapsigargin from releasing more Ca2+, whereas ionomycin added afterward still released some Ca2+. These findings suggest that in human breast cancer cells, DES increases [Ca2+]i by stimulating extracellular Ca2+ influx and also by causing intracellular Ca2+ release from the endoplasmic reticulum. Acute trypan blue exclusion studies suggest that 10-20 NM DES killed cells in a time-dependent manner.

Antineoplastic Agents, Hormonal↗
PubMed2003

Thiol oxidation by 2,2'-dithiodipyridine induced calcium mobilization in MG63 human osteosarcoma cells.

2,2'-dithiodipyridine (2,2'-DTDP), a reactive disulphide that mobilizes Ca(2+) in muscle, induced an increase in cytoplasmic free Ca(2+)concentrations ([Ca(2+)](i)) in MG63 human osteosarcoma cells loaded with the Ca(2+)-sensitive dye fura-2. 2,2'-DTDP acted in a concentration-independent manner with an EC(50) of 50 microM. The Ca(2+) signal comprised an initial spike and a prolonged increase. Removing extracellular Ca(2+) did not alter the Ca(2+) signal, suggesting that the Ca(2+) signal was due to store Ca(2+) release. In Ca(2+)-free medium, the 2,2'-DTDP-induced [Ca(2+)](i) increase was not changed by depleting store Ca(2+) with 50 microM bredfeldin A (a Golgi apparatus permeabilizer), 2 microM carbonylcyanide m-chlorophenylhydrazone (CCCP, a mitochondrial uncoupler), 1 microM thapsigargin (an endoplasmic reticulum Ca(2+)pump inhibitor) or 5 microM ryanodine. Conversely, 2,2'-DTDP pretreatment abolished CCCP and thapsigargin-induced [Ca(2+)](i) increases. 2,2'-DTDP-induced Ca(2+) signals in Ca(2+)-containing medium were not affected by modulation of protein kinase C activity or suppression of phospholipase C activity. However, 2,2'-DTDP-induced Ca(2+) release was inhibited by a thiol-selective reducing reagent, dithiothreitol (5-25 microM) in a concentration-dependent manner. Collectively, this study shows that 2,2'-DTDP induced [Ca(2+)](i) increases in human osteosarcoma cells via releasing store Ca(2+)from multiple stores in a manner independent of protein kinase C or phospholipase C activity. The 2,2'-DTDP-induced store Ca(2+) release appeared to be dependent on oxidation of membranes.

2,2'-Dipyridyl↗
PubMed2003

Novel effect of N-palmitoyl-L-serine phosphoric acid on cytosolic Ca2+ levels in human osteoblasts.

The effect of N-palmitoyl-L-serine phosphoric acid (L-NASPA), which has been used as an inhibitor of lysophosphatidic acid receptors, on intracellular Ca2+ concentration ([Ca2+]i) in human osteosarcoma MG63 cells was measured by using fura-2. L-NASPA (0.1-10 microM) caused a rapid and transient plateau [Ca2+]i rise in a concentration-dependent manner (EC50=0.5 microM). The L-NASPA-induced [Ca2+]i rise was partly reduced by removal of extracellular Ca2+ but was not altered by L-type voltage-gated Ca2+ channel blockers. In Ca2+-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+-ATPase, induced a [Ca2+]i rise, after which the increasing effect of L-NASPA on [Ca2+]i was completely inhibited; also, pretreatment with L-NASPA partly reduced thapsigargin-induced [Ca2+]i rise. U73122, an inhibitor of phospholipase C, abolished histamine (but not L-NASPA)-induced [Ca2+]i rise. Overnight incubation with 1 microM L-NASPA did not affect cell proliferation, but 10-20 microM L-NASPA exerted 4% and 15% inhibition, respectively. Collectively, L-NASPA rapidly increased [Ca2+]i in MG63 cells by evoking both extracellular Ca2+ influx and intracellular Ca2+ release, and is cytotoxic at higher concentrations.

Animals↗
PubMed2003

Oxidation by thimerosal increases calcium levelsin renal tubular cells.

The effect of thimerosal, a reactive oxidant, on cytoplasmic free Ca2+ concentrations ([Ca2+]i) in Madin Darby canine kidney (MDCK) cells was explored by using the Ca2+-sensitive dye fura-2. Thimerosal acted in a concentration-dependent manner with an EC50 of 0.5 microM. The Ca2+ signal comprised a gradual rise and a sustained elevation. Removal of extracellular Ca2+ reduced 80% of the signal. In Ca2+-free medium, the [Ca2+]i rise induced by 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) was completely inhibited by pretreatment with 5 microM thimerosal. The thimerosal (5 microM)-induced Ca2+ release was not changed by inhibition of phospholipase C with 2 microM U73122. Collectively, this study shows that thimerosal induced [Ca2+]i rises in renal tubular cells via releasing store Ca2+ from the endoplasmic reticulum Ca2+ stores in a manner independent of phospholipase C activity.

Animals↗
PubMed2003

Technetium-99m-sestamibi scintimammography to detect breast cancer in patients with paraffinomas or siliconomas after breast augmentation.

As the mechanism of (99)mTc-MIBI scintimammography is different from that of anatomic modalities, the detection of breast cancer should not be affected by prior breast augmentation. The aim of this study was to compare the diagnostic accuracy of (99)mTc-MIBI scintimammography for breast cancer in patients with or without paraffinomas or siliconomas. Twenty-eight women with a history of paraffin or silicone injection into the breasts and 17 without were included. All patients received intravenous injection of 1110 MBq (99)mTc-MIBI and were subsequently examined using high-resolution planar and SPECT imaging 5 minutes after the injection. In the 45 patients with 87 breasts, 21 abnormal breasts were found at scintigraphy. The sensitivity, specificity, and accuracy to detect cancer in these breasts with paraffinomas or siliconomas were 100% (5/5), 92% (46/50), and 93% (51/55), respectively. For the breasts without paraffinomas or siliconomas, the sensitivity, specificity, and accuracy were 92% (11/12), 95% (19/20), and 94% (30/32), respectively, not significantly different (p = 0.51, 0.66, and 0.86, respectively). (99)mTc-MIBI scintimammography is both sensitive and specific for the detection of breast cancer, whether or not paraffinomas or siliconomas are present. The accuracy of scintimammography did not seem to be affected by prior breast augmentation.

Adult↗
PubMed2003

Effect of the antidepressant desipramine on cytosolic Ca(2+) movement and proliferation in human osteosarcoma cells.

In human osteosarcoma MG63 cells, the effect of desipramine, an antidepressant, on intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured by using fura-2. Desipramine (>10 micromol/l) caused a rapid and sustained rise of [Ca(2+)](i) in a concentration-dependent manner (EC(50) = 200 micromol/l). Desipramine-induced [Ca(2+)](i) rise was prevented by 80% by removal of extracellular Ca(2+) but was not altered by voltage-gated Ca(2+) channel blockers. In Ca(2+)-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum (ER) Ca(2+)-ATPase, caused a monophasic [Ca(2+)](i) rise, after which the increasing effect of desipramine on [Ca(2+)](i) was abolished; also, pretreatment with desipramine partly reduced thapsigargin-induced [Ca(2+)](i) increase. U73122, an inhibitor of phospholipase C, did not affect desipramine-induced [Ca(2+)](i) rise. Overnight incubation with 10 micromol/l desipramine did not alter cell proliferation, but killed 32 and 89% of cells at concentrations of 100 and 200 micromol/l, respectively. These findings suggest that desipramine rapidly increases [Ca(2+)](i) in osteoblasts by stimulating both extracellular Ca(2+) influx and intracellular Ca(2+) release, and is cytotoxic at high concentrations.

Antidepressive Agents↗
PubMed2003

Risk factors of mortality after surgical treatment of intestinal obstruction in patients having prior laparotomy for non-malignancy.

BACKGROUND: Intestinal obstruction has remained one of the most common surgical emergencies, and its clinical spectrum has shifted in past decades. The factors contributing to its surgical mortality were studied in these selected patients with a view to finding pointers which help surgeons to identify patients with high surgical risk of mortality. METHODS: Those adult patients who had prior laparotomy for non-malignancy and were operated on for intestinal obstruction were included and studied retrospectively. Thirteen possible risk factors, including co-existing medical illness, tachycardia, preoperative shock, age, bowel ischemia, operative complication, leukocytosis, durations from symptom onset to hospitalization, from hospitalization to operation, and from symptom onset to operation, prior laparotomy number, time interval from last laparotomy to this operation, and operation method, were analyzed using univariate analysis and, then, multivariate analysis to find out the independent risk factors for surgical death. RESULTS: Adhesion-related etiologies were the most common. Still, one-tenth of cases were not adhesion-related. Obstruction in the small bowel (172/176) was more frequent than in the large bowel (4/176). The surgical mortality rate was 6.8% (12/176). The independent risk factors of mortality after surgical treatment were co-existing medical illness, bowel ischemia, preoperative shock, and operative complication. Old age seemed to be a risk factor on univariate anlaysis, but not on multivariate analysis. Duration from symptom onset to hospitalization, from hospitalization to operation, or from symptom onset to operation was not significantly related to surgical mortality. CONCLUSIONS: High risk patients could be identified by 4 independent factors: coexisting medical illness, bowel ischemia, preoperative shock, and operative complication. Old age itself was not an independent risk factor.

Adolescent↗
PubMed2002

The anti-breast cancer drug tamoxifen alters Ca2+ movement in Chinese hamster ovary (CHO-K1) cells.

The anti-breast cancer drug tamoxifen has recently been shown to cause an increase in intracellular free-Ca(2+) concentrations ([Ca(2+)](i)) in renal tubular cells, breast cells and bladder cells. Because tamoxifen is known to alter ovary function in human patients and in rats, the present study was aimed at exploring whether tamoxifen could alter Ca(2+) movement in Chinese hamster ovary (CHO-K1) cells. Cytosolic free-Ca(2+) levels in populations of cells have been explored by using fura-2 as a fluorescent Ca(2+) indicator. Tamoxifen at concentrations above 1 micro M increased [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 8 micro M. The Ca(2+) signal was reduced by removing extracellular Ca(2+), but was not affected by nifedipine, verapamil, diltiazem or ICI 182,780 (an estrogen receptor antagonist). Pretreatment with 1 micro M thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor) to deplete the endoplasmic reticulum Ca(2+) abolished 10 micro M tamoxifen-induced Ca(2+) release. Neither inhibition of phospholipase C with 2 micro M U73122 nor depletion of ryanodine-sensitive Ca(2+) stores with 50 micro M ryanodine affected tamoxifen-induced Ca(2+) release. Cell proliferation assays using ELISA revealed that overnight incubation with 5-10 micro M tamoxifen inhibited cell proliferation by 20%, and 20 micro M tamoxifen killed all cells. Together, the results suggest that, in CHO-K1 cells, tamoxifen induced a [Ca(2+)](i) increase by causing store-Ca(2+) release from the endoplasmic reticulum in an phospholipase C-independent manner, and by inducing Ca(2+) influx. The action of tamoxifen appears to be dissociated from estrogen receptor activation. Longer incubation with tamoxifen (>5 micro M) was cytotoxic.

Animals↗
PubMed2002

Effect of olvanil (N-vanillyl-cis-9-octadecenoamide) on cytosolic Ca2+ increase in renal tubular cells.

In canine renal tubular cells, effect of olvanil, a presumed cannabinoid and vanilloid receptor modulator, on intracellular Ca2+ concentration ([Ca2+]i) was measured by using fura-2. Olvanil (5-100 microM) caused a rapid and sustained [Ca2+]i rise in a concentration-dependent manner. Olvanil-induced [Ca2+]i rise was prevented by 70 and 90% by removal of extracellular Ca2+ and La3+, respectively, but was not changed by dihydropyridines, verapamil and diltiazem. In Ca2+-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a monophasic [Ca2+]i rise, after which the increasing effect of olvanil on [Ca2+]i was abolished; also, pretreatment with olvanil partly reduced thapsigargin-induced [Ca2+]i rise. U73122, an inhibitor of phoispholipase C, abrogated ATP-, but partly inhibited olvanil-, induced [Ca2+]i rise. Two cannabinoid receptor antagonists (AM251 and AM281; 5 microM) and a vanilloid receptor antagonist (capsazepine; 100 microM) did not alter olvanil (50 microM)-induced [Ca2+]i rise. These results suggest that olvanil rapidly increases [Ca2+]i in renal tubular cells, by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release via mechanism(s) independent of stimulation of cannabinoid and vanilloid receptors.

Animals↗
PubMed2002

Effect of (-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl) cyclohexanol (CP55,940) on intracellular Ca2+ levels in human osteosarcoma cells.

The study was undertaken to explore the effect of CP55,940 ((-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol), a drug commonly used as a CB1/CB2 cannabinoid receptor agonist, on intracellular free Ca2+ levels ([Ca2+]i) in MG63 human osteoblast-like epithelial cells. [Ca2+]i was measured in suspended cells by using the fluorescent dye fura-2 as an indicator. At concentrations between 2-20 microM, CP55,940 increased [Ca2+]i in a concentration-dependent manner with an EC50 of 8 microM. The [Ca2+] signal comprised an initial rise, a slow decay, and a sustained phase. CP55940 (10 microM)-induced [Ca2+]i signal was not altered by 5 microM of two cannabinoid receptor antagonists (AM-251, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole3-carboxamide; AM-281, 1-(2,4-Dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide). Extracellular Ca2+ removal decreased the maximum value of the Ca2+ signals by 50%. CP55,940 induced quench of fura-2 fluorescence by Mn2+ (50 microM), suggesting the presence of Ca2+ influx across the plasma membrane. CP55,940 (10 microM)-induced [Ca2+]i increase in Ca(2+)-free medium was inhibited by 84% by pretreatment with 1 microM thapsigargin, an endoplasmic reticulum Ca2+ pump inhibitor. Conversely, pretreatment with 10 microM CP55,940 in Ca(2+)-free medium abolished thapsigargin-induced [Ca2+]i increase. At 1 microM, nifedipine, verapamil, and diltiazem did not alter CP55, 940 (10 microM)-induced [Ca2+]i increase. CP55,940 (20 microM)-induced Ca2+ release was not affected when phospholipase C was inhibited by 2 microM U73122 (1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino) hexyl)-1H-pyrrole-2,5-dione). CP55,940 (20 microM) did not induce acute cell death after incubation for 30 min as assayed by trypan blue exclusion. Collectively, CP55,940 induced significant [Ca2+]i increases in osteoblasts by releasing store Ca2+ from thapsigargin-sensitive stores and by causing Ca2+ entry. The CP55,940's action appears to be independent of stimulation of CB1 cannabinoid receptors.

Calcium↗
PubMed2002

Effect of NPC-15199 on Ca2+ levels in renal tubular cells.

In Madin-Darby canine kidney (MDCK) cells, effect of NPC-15199 on intracellular Ca2+ concentration ([Ca2+]i) was investigated by using fura-2. NPC-15199 (100-1000 microM) caused a rapid and sustained increase of [Ca2+]i in a concentration-dependent manner (EC50=500 microM). NPC-15199-induced [Ca2+]i rise was prevented by 70% by removal of extracellular Ca2+, but was not changed by dihydropyridines, verapamil and diltiazem. In Ca2+-free medium, carbonylcyanide m-chlorophenylhydrazone (CCCP; 2 microM), a mitochondrial uncoupler, and thapsigargin (1 microM), an inhibitor of the endoplasmic reticulum (ER) Ca2(+)-ATPase, caused a monophasic [Ca2+]i rise, respectively, after which the increasing effect of NPC-15199 (1 mM) on [Ca2+]i was substantially attenuated; also, pretreatment with NPC-15199 abolished CCCP- and thapsigargin-induced [Ca2+]i rises. U73122, an inhibitor of phospholipase C, [corrected] abolished 10 microM ATP (but not 1 mM NPC-15199)-induced [Ca2+]i rise. These results suggest that NPC-15199 rapidly increases [Ca2+]i by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release via as yet unidentified mechanism(s).

Animals↗
PubMed2002

Effect of clomiphene on Ca(2+) movement in human prostate cancer cells.

The effect of clomiphene, an ovulation-inducing agent, on cytosolic free Ca(2+) levels ([Ca(2+)](i)) in populations of PC3 human prostate cancer cells was explored by using fura-2 as a Ca(2+) indicator. Clomiphene at concentrations between 10-50 microM increased [Ca(2+)](i) in a concentration-dependent manner. The [Ca(2+)](i) signal was biphasic with an initial rise and a slow decay. Ca(2+) removal inhibited the Ca(2+) signal by 41%. Adding 3 mM Ca(2+) increased [Ca(2+)](i) in cells pretreated with clomiphene in Ca(2+)-free medium, confirming that clomiphene induced Ca(2+) entry. In Ca(2+)-free medium, pretreatment with 50 microM brefeldin A (to permeabilize the Golgi complex), 1 microM thapsigargin (to inhibit the endoplasmic reticulum Ca(2+) pump), and 2 microM carbonylcyanide m-chlorophenylhydrazone (to uncouple mitochondria) inhibited 25% of 50 microM clomiphene-induced store Ca(2+) release. Conversely, pretreatment with 50 microM clomiphene in Ca(2+)-free medium abolished the [Ca(2+)](i) increase induced by brefeldin A, thapsigargin or carbonylcyanide m-chlorophenylhydrazone. The 50 microM clomiphene-induced Ca(2+)release was unaltered by inhibiting phospholipase C with 2 microM 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122). Trypan blue exclusion assay suggested that incubation with clomiphene (50 microM) for 2-15 min induced time-dependent decrease in cell viability by 10-50%. Collectively, the results suggest that clomiphene induced [Ca(2+)](i) increases in PC3 cells by releasing store Ca(2+) from multiple stores in an phospholipase C-independent manner, and by activating Ca(2+) influx; and clomiphene was of mild cytotoxicity.

Brefeldin A↗