Anthocyanins in Cornus alternifolia, Cornus controversa, Cornus kousa and Cornus florida fruits with health benefits

The anthocyanins in native Cornus alternifolia, Cornus controversa, Cornus kousa and Cornus florida were quantified by HPLC and characterized by spectroscopic methods. The analyses of C. alternifolia and C. controversa revealed that both contained , and , respectively. Similarly, C. florida and C. kousa showed identical anthocyanin profiles with major anthocyanins as and cyanidin 3-O-glucoside (6), respectively. The amount of anthocyanins , and in C. alternifolia and C. controversa were 8.21, 8.44 and 0.02 mg; and 7.74, 5.92, and 0.02 mg/g of fresh fruits, respectively. The anthocyanins and in C. kousa and C. florida were 0.02 and 0.16 mg; and 0.62 and 0.03 mg/g fresh fruits, respectively. Anthocyanins and were not studied earlier for their inhibition of lipid peroxidation, cyclooxygenase enzymes (COX-1 and COX-2), and tumor cell proliferation. At 50 microg/mL, anthocyanins and inhibited lipid peroxidation by 71% and 68%, respectively. Similarly, they inhibited COX-1 enzymes by 39% and 49% and COX-2 enzyme by 54% and 48%, respectively, at 100 microg/mL. Anthocyanin displayed 50% growth inhibition (IC(50)) at 21, 25, 50, 60, and 75 microg/mL, against HCT-116 (colon), MCF-7 (breast), NCI-H460 (lung), SF-268 (central nervous system CNS), and AGS (stomach) human tumor cell lines, respectively. Similarly, IC(50) values for anthocyanin were 38, 30, 76, 100, and 100 microg/mL against HCT-116, MCF-7, NCI H460, SF-268, and AGS, respectively. This is the first report of the quantification and biological activities of anthocyanins in C. alternifolia, C. kousa and C. florida in addition to the anthocyanins not previously quantified in C. controversa.     

Human tumor cell growth inhibition by nontoxic anthocyanidins, the pigments in fruits and vegetables

Anthocyanidins, the aglycones of anthocyanins, impart brilliant colors in many fruits and vegetables. The widespread consumption of diets rich in anthocyanin and anthocyanidins prompted us to determine their inhibitory effects on human cancer cell proliferation. Five anthocyanidins, cyanidin (1), delphinidin (2), pelargonidin (3), petunidin (4) and malvidin (5), and four anthocyanins, cyanidin-3-glucoside, cyanidin-3-galactoside, delphinidin-3-galactoside and pelargonidin-3-galactoside were tested for cell proliferation inhibitory activity against human cancer cell lines, AGS (stomach), HCT-116 (colon), MCF-7 (breast), NCI H460 (lung), and SF-268 (Central Nervous System, CNS) at 12.5-200 microg/mL concentrations. The viability of cells after exposure to anthocyanins and anthocyanidins was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric methods. The anthocyanins assayed did not inhibit cell proliferation of cell lines tested at 200 microg/mL. However, anthocyanidins showed cell proliferation inhibitory activity. Malvidin inhibited AGS, HCT-116, NCI-H460, MCF-7 and SF-268 cell growth by 69, 75.7, 67.7, 74.7 and 40.5%, respectively, at 200 microg/mL. Similarly, pelargonidin inhibited AGS, HCT-116, NCI H460, MCF-7 and SF-268 cell growth by 64, 63, 62, 63 and 34%, respectively, at 200 microg/mL. At 200 microg/mL, cyanidin, delphinidin and petunidin inhibited the breast cancer cell growth by 47, 66 and 53%, respectively. This is the first report of tumor cell proliferation inhibitory activity by anthocyanidins.     

Development and use of a high-throughput bacterial DNA gyrase assay to identify mammalian topoisomerase II inhibitors with whole-cell anticancer activity

A high-throughput screen (HTS) was developed and used to identify inhibitors of bacterial DNA gyrase. Among the validated hits were 53 compounds that also inhibited mammalian topoisomerase II with IC(50) values of <12.5 micro g/mL for 51 of them. Using computational methods, these compounds were subjected to cluster analysis to categorize them according to their chemical and structural properties. Nine compounds from different clusters were tested for their whole-cell inhibitory activity against 3 cancer cell lines-NCI-H460 (lung), MCF7 (breast), and SF-268 (CNS)-at a concentration of 100 micro M. Five compounds inhibited cell growth by >50% for all 3 cell lines tested. These compounds were tested further against a panel of 53 to 57 cell lines representing leukemia, melanoma, colon, CNS, ovarian, renal, prostate, breast, and non-small cell lung cancers. In this assay, PGE-7143417 was found to be the most potent compound, which inhibited the growth of all the cell lines by 50% at a concentration range of 0.31 to 2.58 micro M, with an average of 1.21 micro M. An additional 17 compounds were also tested separately against a panel of 10 cell lines representing melanoma, colon, lung, mammary, ovarian, prostate, and renal cancers. In this assay, 4 compounds-PGE-3782569, PGE-7411516, PGE-2908955, and PGE-3521917-were found to have activity with concentrations for 50% cell growth inhibition in the 0.59 to 3.33, 22.5 to 59.1, 7.1 to >100, and 24.7 to >100 micro M range.     

Inhibitory effects of flavonol glycosides from Cinnamomum osmophloeum on inflammatory mediators in LPS/IFN-gamma-activated murine macrophages

Four kaempferol glycosides were isolated from the leaves of Cinnamomum osmophloeum Kaneh, a Taiwan endemic tree. These compounds namely, kaempferitrin (1), kaempferol 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-7-O-alpha-L-rhamnopyranoside (2), kaempferol 3-O-beta-D-apiofuranosyl-(1-->2)-alpha-L-arabinofuranosyl-7-O-alpha-L-rhamnopyranoside (3), and kaempferol 3-O-beta-D-apiofuranosy-(1-->4)-alpha-L-rhamnopyranosyl-7-O-alpha-L-rhamnopyranoside (4). The structure of compound 2 was determined by spectroscopic analyses and acid hydrolysis. The isolates 1-4 were evaluated as inhibitors of some macrophage functions involved in the inflammatory process. These four compounds inhibited lipopolysaccharide (LPS) and interferon (IFN)-gamma-induced nitric oxide (NO), and cytokines [tumor necrosis factor (TNF)-alpha and interleukin (IL)-12] in a dose-dependent manner. The concentration of 50% inhibition (IC(50)) of NO by compounds 1, 3, 4 were 40, 15, 20microM, respectively. In parallel, these concentrations were approximately in a similar manner to that observed for TNF-alpha and IL-12 production. However, compound 2 inhibited NO and cytokines production by 30% at 100microM concentration. On the other hand, compounds 3 and 4 showed no inhibitory effect on the production of NO from macrophages, when inducible NO synthase was already expressed by the stimulation with LPS and IFN-gamma. Taken together, our results provide evidence that isolates of C. osmophloeum possess an anti-inflammatory potential which constitutes a previously unrecognized biological activity.     

Constituents in Easter lily flowers with medicinal activity

Easter lily (Lilium longiflorum) flowers have been used in traditional medicine for alleviating many ailments. However, the chemical basis of its bioactivity has not been investigated. We have determined bioactive components in Easter lily flowers using lipid peroxidation and cyclooxygenase enzyme inhibitory assays and found to be kaempferol (1), kaempferol glycosides (2, 3, 4, 8, 9 and 10), quercetin glycosides (5, 6 and 7), a regaloside (11), a chalcone (12) and a fatty acid fraction (13). The structures of compounds were determined by NMR, IR, UV/VIS and mass spectroscopic studies. Compound 1 showed the highest COX-1 inhibition (94.1%) followed by 3, 8 and 12 with 38.7, 30.8 and 32.4%, respectively. Only compound 1 inhibited COX-2 enzyme by 36.9% at 80 ppm. In lipid peroxidation inhibitory assay, kaempferol showed 37 and 100 % inhibitions at 1 and 10 ppm, respectively. At 10 ppm, more than 20% inhibition was observed for compounds 4, 7, 10, 11 and 12 and 53% for compound 3. The compounds reported in here are isolated for the first time from Easter lily flowers including novel compounds 10, 11 and 12. Our results suggest that kaempferol and quercetin flavonoids contributed to the anecdotal medicinal properties of Easter lily flowers.     

Somatic mutations of CASP3 gene in human cancers

Failure of apoptosis is one of the hallmarks of cancer. As an execution-phase caspase, caspase-3 plays a crucial role during apoptosis. To explore the possibility that the genetic alterations of CASP3, which encodes caspase-3, might be involved in the development of human tumors, we analyzed the entire coding region and all splice sites of human CASP3 gene for the detection of somatic mutations in a series of 944 human tumors, including 165 stomach carcinomas, 95 colon carcinomas, 76 breast carcinomas, 80 hepatocellular carcinomas, 181 non-small cell lung cancers, 45 acute leukemias, 28 multiple myelomas, 12 medulloblastomas, 15 Wilms tumors, 12 renal cell carcinomas, 40 esophagus carcinomas, 33 urinary bladder carcinomas, 33 laryngeal carcinomas, and 129 non-Hodgkin lymphomas. Overall, we detected 14 somatic mutations of the CASP3 gene, including six missense and four silent mutations, two mutations in the introns, one mutation in the 5-untranslated region, and one mutation in the 3-untranslated region. The mutations were observed in four of 98 colon carcinomas (4.1%), four of 181 non-small cell lung cancers (2.2%), two of 129 non-Hodgkin lymphomas (1.6%), two of 165 stomach carcinomas (1.2%), one of 80 hepatocellular carcinomas (1.3%), and one of 28 multiple myelomas (3.6%). This is the first report on CASP3 gene mutations in human tumors; these data indicate that the CASP3 gene is occasionally mutated in human tumors.     

Flavonoids: potent inhibitors of arachidonate 5-lipoxygenase

Various flavonoids were found to be relatively selective inhibitors of arachidonate 5-lipoxygenase which initiates the biosynthesis of leukotrienes with the activity of slow reacting substance of anaphylaxis. Cirsiliol (3',4',5-trihydroxy-6,7-dimethoxyflavone) was most potent, and the enzyme partially purified from rat basophilic leukemia cells was inhibited by 97% at a concentration of 10 microM (IC50, about 0.1 microM). 12-Lipoxygenases from bovine platelets and porcine leukocytes were also inhibited but at higher concentrations (IC50, about 1 microM), and fatty acid cyclooxygenase purified from bovine vesicular gland was scarcely affected. The compound at 10 microM suppressed by 99% the immunological release of slow reacting substance of anaphylaxis from passively sensitized guinea pig lung (IC50, about 0.4 microM).     

Inhibition of estrogen receptor alpha expression and function in MCF-7 cells by kaempferol

Estrogens are mitogenic for estrogen receptor (ER)-positive breast cancer cells. Current treatment of ER-positive breast tumors is directed towards interruption of estrogen activity. We report that treatment of ER-positive breast cancer cells with kaempferol resulted in a time- and dose-dependent decrease in cell number. The concentration required to produce 50% growth inhibition at 48 h was approximately 35.0 and 70.0 microM for ER-positive and ER-negative breast cancer cells, respectively. For MCF-7 cells, a reduction in the ER-alpha mRNA equivalent to 50, 12, 10% of controls was observed 24 h after treatment with 17.5, 35.0, and 70.0 microM of kaempferol, respectively. Concomitantly, these treatments led to a 58, 80, and 85% decrease in ER-alpha protein. The inhibitory effect of kaempferol on ER-alpha levels was seen as early as 6 h post-treatment. Kaempferol treatment also led in a dose-dependent decrease in the expression of progesterone receptor (PgR), cyclin D1, and insulin receptor substrate 1 (IRS-1). Immunocytochemical study revealed that ER-alpha protein in kaempferol-treated MCF-7 cells formed an aggregation in the nuclei. Kaempferol also induced degradation of ER-alpha by a different pathway than that were observed for the antiestrogen ICI 182,780 and estradiol. Estradiol-induced MCF-7 cell proliferation and expression of the estrogen-responsive-element-reporter gene activity were abolished in cells co-treated with kaempferol. These findings suggest that modulation of ER-alpha expression and function by kaempferol may be, in part, responsible for its anti-proliferative effects seen in in vitro.     

Inhibition of human tumor cell proliferation by novel anthraquinones from daylilies

Daylilies (Hemerocallis) are used medicinally in eastern Asia and extracts of the plant had been shown to inhibit cell proliferation and induce cancer cells to undergo differentiation. In our studies of the constituents of Hemerocallis fulva var. 'Kwanzo' roots, we isolated a series of new [kwanzoquinones A (1), B (2), C (4), D (5), E (6), F (7), G (9)] and known [2-hydroxychrysophanol (3) and rhein (8)] anthraquinones. These compounds were tested in order to determine their potential roles as cancer cell growth inhibitors. Kwanzoquinones A-C and E, kwanzoquinone A and B monoacetates (1a and 2a), 2-hydroxychrysophanol, and rhein inhibited the proliferation of human breast, CNS, colon, and lung cancer cells with GI50 values between 1.8 to 21.1 microg/mL. However, upon exposure of the cancer cells to the GI50 concentrations of the bioactive anthraquinones, most of the cancer cell lines exhibited higher than anticipated levels of cell viability. Co-incubation of the anthraquinones with vitamins C and E increased the viability of breast cancer cells. In contrast, vitamins C and E potentiated the cytotoxic effects of the anthraquinones against the colon cancer cells. None of the anthraquinones inhibited the activity of topoisomerase.     

Discovery of certain benzyl/phenethyl thiazolidinone-indole hybrids as potential anti-proliferative agents: Synthesis,molecular modeling and tubulin polymerization inhibition study

A series of certain benzyl/phenethyl thiazolidinone-indole hybrids were synthesized for the study of anti-proliferative activity against A549, NCI-H460 (lung cancer), MDA-MB-231 (breast cancer), HCT-29 and HCT-15 (colon cancer) cell lines by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). We found that compound G37 displayed highest cytotoxicity with IC₅₀ value of 0.92 ± 0.12 µM towards HCT-15 cancer cell line among all the synthesized compounds. Moreover, compound G37 was also tested on normal human lung epithelial cells (L132) and was found to be safe in contrast to HCT-15 cells. The lead compound G37 showed significant G2/M phase arrest in HCT-15 cells. Additionally, compound G37 significantly inhibited tubulin polymerization with IC₅₀ value of 2.92 ± 0.23 µM. Mechanistic studies such as acridine orange/ethidium bromide (AO/EB) dual staining, DAPI nuclear staining, annexinV/propidium iodide dual staining, clonogenic growth inhibition assays inferred that compound G37 induced apoptotic cell death in HCT-15 cells. Moreover, loss of mitochondrial membrane potential with elevated intracellular ROS levels was observed by compound G37. These compounds bind at the active pocket of the α/β-tubulin with higher number of stable hydrogen bonds, hydrophobic and arene-cation interactions confirmed by molecular modeling studies.     

Characterization of CGS 8515 as a selective 5-lipoxygenase inhibitor using in vitro and in vivo models

CGS 8515 inhibited 5-hydroxyeicosatetraenoic acid (5-HETE) and leukotriene B4 synthesis in guinea pig leukocytes (IC50 = 0.1 microM). The compound did not appreciably affect cyclooxygenase (sheep seminal vesicles), 12-lipoxygenase (human platelets), 15-lipoxygenase (human leukocytes) and thromboxane synthetase (human platelets) at concentrations up to 100 microM. CGS 8515 inhibited A23187-induced formation of leukotriene products in whole blood (IC50 values of 0.8 and 4 microM, respectively, for human and rat) and in isolated rat lung (IC50 less than 1 microM) in vitro. The selectivity of the compound as a 5-lipoxygenase inhibitor was confirmed in rat whole blood by the 20-70-fold separation of inhibitory effects on the formation of leukotriene from prostaglandin products. Ex vivo and in vivo studies with rats showed that CGS 8515, at an oral dose of 2-50 mg/kg, significantly inhibited A23187-induced production of leukotrienes in whole blood and in the lung. The effect persisted for at least 6 h in the ex vivo whole blood model. CGS 8515, at oral doses as low as 5 mg/kg, significantly suppressed exudate volume and leukocyte migration in the carrageenan-induced pleurisy and sponge models in the rat. Inhibitory effects of the compound on inflammatory responses and leukotriene production in leukocytes and target organs are important parameters suggestive of its therapeutic potential in asthma, psoriasis and inflammatory conditions.     

Inhibition of cGMP-dependent protein kinases potently decreases neutrophil spontaneous apoptosis

The signalling pathways mediating neutrophil spontaneous apoptosis are still largely unknown. We report that the indolocarbazole compound KT5823, a specific inhibitor of cGMP-dependent protein kinases (cGK), dose-dependently inhibited spontaneous apoptosis of neutrophils. At the concentration eliciting the maximum effect (8 microM), it decreased apoptosis from 72.42+/-12.79% to 45.86+/-7.22% (p=0.0002, n=6). Similarly, the isoquinoline sulfonamide compound H89, another cGK inhibitor, prevented neutrophil apoptosis. At the concentration eliciting the maximum effect (20 microM), it decreased apoptosis from 72.42+/-12.79% to 31.84+/-10.70% (p=0.0004, n=6). The maximum effect of KT5823 and H89 was comparable to that of GM-CSF and LPS, respectively. Moreover, YC-1, a soluble guanylate cyclase activator, and 4-([3',4',-(methylenedioxy)benzyl]amino)-6-methoxyquinazoline, a specific phosphodiesterase 5 inhibitor, enhanced neutrophil apoptosis, and their effect was antagonised by KT5823. Taken together, these observations highlight a new role of cGK as important mediators of neutrophil spontaneous apoptosis.     

Flavonol content of guard cell and mesophyll cell protoplasts isolated from Vicia faba leaves

Guard cells of the lower epidermis of leaflets of Vicia faba L. cv. Weißkernige Hangdown contain several kaempferol 3,7-O-glycosides. This was demonstrated for the first time by the use of isolated, highly purified guard cell protoplasts for flavonol estimation and quantitation. From a total of ca 12 kaempferol glycosides, three were identified by comparative thin layer chromatography and high performance liquid chromatography as kaempferol 3-O-glucoside 7-O-rhamnoside (major component), 3-O-rhamnogalactoside 7-O-rhamnoside and 3,7-O-bisglucoside (minor components). On average, the total flavonol content was estimated to be 85 fmol protoplast⁻¹. From comparative investigations including alkaline-induced (green) fluorescence characteristics of flavonols and UV-microscopical studies we suggest that kaempferol glycosides are present in guard cells and epidermal cells in similar quantities, and that these compounds are in the vacuole.
By contrast, mesophyll protoplasts have a low flavonol content (one sixth that of guard cells). In spite of the different total flavonol contents, individual components of each cell-type are the same. However, they show differences in their quantitative distribution.     

Anti-tumor abietane diterpenes from the cones of Sequoia sempervirens

A new abietane, namely, 20-hydroxyferruginol (1), together with known ferruginol (2), 18-hydroxyferruginol (3), sugiol (4), and 6alpha-hydroxysugiol (5), were isolated from the cones of Sequoia sempervirens. Their structures were elucidated through spectral data. Compounds 1 and 5 strongly inhibited colon, lung, and breast human tumors and oncogene transformed cells with GI(50) 2-5 microg/mL.     

Synthesis and biological activities of novel dexibuprofen tetraacetylriboflavin conjugates

A series of novel dexibuprofen derivatives covalently linked via alkylene spacers of variable length to tetraacetylated riboflavin have been developed. The target compounds became accessible by reaction of the chloromethyl ester of dexibuprofen with tetraacetylriboflavin (compound 7) or by synthesis of the appropriate N3-(omega-iodoalkyl)-2',3',4',5'-Tetraacetylriboflavin followed by treatment with dexibuprofen (derivatives 8-11), respectively. Biological screening revealed that the target compounds exhibit antiproliferative effects on MCF-7 breast cancer and HT-29 colon carcinoma cells with IC50 values in the range of 8-15 microM. Enzymatic studies on human platelets indicated significant COX-1 inhibitory activities of the target compounds.     

Enzymatic hydrolysis of green tea seed extract and its activity on 5alpha-reductase inhibition

Two kaempferol glycosides were isolated from green tea seed extract (GTSE). After conducting a structure analysis, these two compounds were identified as kaempferol-3-O-[2-O-beta-D-galactopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside (compound 1) and kaempferol-3-O-[2-O-beta-D-xylopyranosyl-6-O-alpha-L-rhanmopyranosyl]-beta-D-glucopyranoside (compound 2). These two compounds were hydrolysed by o-glycolytic enzymes for the production of kaempferol. After performing several reactions, we found the optimum enzyme combination, a reaction with beta-galactosidase and hesperidinase. Finally, we produced kaempferol of above 95% purity. The 5alpha-reductase inhibition activities of GTSE hydrolysate (GTSE-H) containing kaempferol were evaluated by the contact cell-based metabolic method using a stable HEK 293 cell line. GTSE-H showed a good inhibition effect on HEK 293 cell lines both type 1 and type 2 on 5alpha-reductase. Especially, GTSE-H inhibited type 2 with kaempferol content dependency. The results indicate that the inhibition activity of hydrolysate on 5alpha-reductase type 2 increases in accordance with kaempferol content.     

Second messengers in platelet aggregation evoked by serotonin and A23187, a calcium ionophore.

We investigated the combined effect of 5-hydroxytryptamine (5-HT, serotonin) and calcium ionophore (A23187) on human platelet aggregation. Aggregation, monitored at 37 degrees C using a Dual-channel Lumi-aggregometer, was recorded for 5 min after challenge by a change in light transmission as a function of time. 5-HT (2-200 microM) alone did not cause platelet aggregation, but markedly potentiated A23187 (low dose) induced aggregation. Inhibitory concentration (IC50) values for a number of compounds were calculated as means +/- SEM from dose-response determinations. Synergism between 5-HT (2-5 microM) and A23187 (0.5-2 microM) was inhibited by 5-HT receptor blockers, methysergide (IC50 = 18 microM) and cyproheptadine (IC50 = 20 microM), and calcium channel blockers (verapamil and diltiazem, IC50 = 20 microM and 40 microM respectively). Interpretation of the effects of these blockers is complicated by their lack of specificity. Similarly, U73122, an inhibitor of phospholipase C (PLC), blocked the synergistic effect at an IC50 value of 9.2 microM. Wortmannin, a phosphatidylinositide 3-kinase (PI 3-K) inhibitor, also blocked the response (IC50 = 2.6 microM). However, neither genistein, a tyrosine-specific protein kinase inhibitor, nor chelerythrine, a protein kinase C inhibitor, affected aggregation at concentrations up to 10 microM. We conclude that the synergistic interaction between 5-HT and ionophore may be mediated by activation of PLC/Ca2+ and PI 3-kinase signalling pathways, but definitive proof will require other enzyme inhibitors with greater specificity.     

A "virtual gland" method for quantifying epithelial fluid secretion

We developed a new apparatus, the virtual gland (VG), for measuring the rate of fluid secretion (Jv), its composition, and the transepithelial potential (TEP) in cultured epithelial cells under open circuit. The VG creates a 10-microl chamber above the apical surface of epithelial cells on a Costar filter with a small hole leading to an oil-filled reservoir. After the chamber is primed with a fluid of choice, secreted fluid is forced through the hole into the oil, where it forms a bubble that is monitored optically to determine Jv and collected for analysis. Calu-3 cells were mounted in the VG with a basolateral bath consisting of Krebs-Ringer bicarbonate buffer at 37 degrees C. Basal Jv was 2.7 +/- 0.1 microl x cm(-2) x h(-1) (n = 42), and TEP was -9.2 +/- 0.6 mV (n = 33); both measures were reduced to zero by ouabain (n = 6) x Jv and TEP were stimulated 64 and 59%, respectively, by 5 microM forskolin (n = 10), 173 and 101% by 1 mM 1-ethyl-2-benzimidazolinone (n = 5), 213 and 122% by 333 nM thapsigargin (n = 5), and 520 and 240% by forskolin + thapsigargin (n = 6). Basal Jv and TEP were inhibited to 82 and 63%, respectively, with 10 microM bumetanide (n = 5), 71 and 82% with 100 microM acetazolamide (n = 5), and 47 and 56% with 600 microM glibenclamide (n = 4). Basal Jv and TEP were 52 and 89% of control values, respectively, after HCO3- replacement with HEPES (n = 16). The net HCO3- concentration of the secreted fluid was close to that of the bath (25 mM), except when stimulated with forskolin or VIP, when it increased (approximately 80 mM). These results validate the use of the VG apparatus and provide the first direct measures of Jv in Calu-3 cells.     

Pressor responses to platelet-activating factor and thromboxane are mediated by Rho-kinase

Platelet-activating factor (PAF) contracts smooth muscle of airways and vessels primarily via release of thromboxane. Contraction of smooth muscle is thought to be mediated either by calcium and inositol trisphosphate (IP(3))-dependent activation of the myosin light chain kinase or, alternatively, via the recently discovered Rho-kinase pathway. Here we investigated the contribution of these two pathways to PAF and thromboxane receptor-mediated broncho- and vasoconstriction in two different rat models: the isolated perfused lung (IPL) and precision-cut lung slices. Inhibition of the IP(3) receptor (1-10 microM xestospongin C) or inhibition of phosphatidylinositol-specific PLC (30 microM L-108) did not affect bronchoconstriction but attenuated the sustained vasoconstriction by PAF. Inhibition of myosin light chain kinase (35 microM ML-7) or of calmodulin kinase kinase (26 microM STO609), which regulates the phosphorylation of the myosin light chain, had only a small effect on PAF- or thromboxane-induced pressor responses. Similarly, calmidazolium (10 microM), which inhibits calmodulin-dependent proteins, only weakly reduced the airway responses. In contrast, Y-27632 (10 microM), a Rho-kinase inhibitor, attenuated the thromboxane release triggered by PAF and provided partial or complete inhibition against PAF- and thromboxane-induced pressor responses, respectively. Together, our data indicate that PAF- and thus thromboxane receptor-mediated smooth muscle contraction depends largely on the Rho-kinase pathway.