Biomedical subjects

K Momose

Publications and source records attributed to K Momose.

At least 91 records · Page 5Linked to original sources

PubMed1995

Sensitizing effect of lysophosphatidic acid on mechanoreceptor-linked response in cytosolic free Ca2+ concentration in cultured smooth muscle cells.

We found that lysophosphatidic acid (LPA) sensitizes response in cytosolic free Ca2+ concentration ([Ca2+]i) to mechanical stimulation in cultured longitudinal muscle cells from guinea pig ileum. [Ca2+]i was transiently increased by spritzing of bath solution onto cells as mechanical stimulation in the presence of LPA, but not in absence of LPA. The effect was reversible and concentration-dependent (1-30 nM). Ga3+ but not nicardipine inhibited the [Ca2+]i transient in the presence of LPA. Phosphatidic acid also induced the sensitization, but the effective concentration was more than 10 times higher than in LPA. Histamine and carbachol did not have any sensitizing effect to mechanical stimulation. These results show that LPA sensitizes mechanoreceptor-linked response, suggesting that LPA may play an important role in mechanotransduction mechanisms as an endogenous regulatory factor.

Animals↗

PubMed1995

Hepatocyte growth factor-induced calcium waves in hepatocytes as revealed with rapid scanning confocal microscopy.

Cytosolic Ca2+ transients induced by hepatocyte growth factor (HGF) were imaged in primary cultured rat hepatocytes using newly developed rapid scanning confocal microscopes and indo-1. HGF (40 ng/ml) increased cytosolic free Ca2+ concentration ([Ca2+]i) in about 60% of hepatocytes, in 45% of which the increases were oscillatory. In each of the oscillatory hepatocytes, the repetitive increases in [Ca2+]i originated from a specific same region adjacent to the cell membrane and propagated across the cell like waves. Phenylephrine (10 microM) also induced Ca2+ waves. The locus where HGF-induced Ca2+ waves and phenylephrine-induced Ca2+ waves were originated was the same, and there was a correlation in the peak height between HGF-induced Ca2+ waves and phenylephrine-induced Ca2+ waves in each cell, although the mechanisms of inositol 1,4,5-trisphosphate (ins(1,4,5)P3) formation induced by HGF should be different from those by phenylephrine. On the other hand, there was no correlation between sensitivity of each cell to HGF and that to phenylephrine which were measured as latent periods prior to Ca2+ rises after an addition of the agonists. These results suggested the following: the spatial patterns of Ca2+ waves were decided by a common mechanism, probably not the propagation of ins(1,4,5)P3 but the distribution of ins(1,4,5)P3-sensitive Ca2+ pools; sensitivities of each cell to the agonists did not mainly depend on the common mechanism.

Adrenergic alpha-Agonists↗

PubMed1995

Pharmacological characterization of SR 48692 sensitive neurotensin receptor in human pancreatic cancer cells, MIA PaCa-2.

Previously, one type of human neurotensin receptor has been molecularly cloned. Recently, it has been proposed that a subtype of neurotensin receptor exists, which is not sensitive to newly synthesized neurotensin receptor antagonist SR 48692. In this study, we characterize the pharmacological properties of neurotensin receptor expressed in human pancreatic cancer cells, MIA PaCa-2. In binding studies with [3H]neurotensin, the data fit a model for a single population of high-affinity binding sites that are competitively antagonized by SR 48692. The rank order of the equilibrium dissociation rate constants for neurotensin(8-13), neurotensin, neuromedin N, [Ala11] neurotensin(8-13), and SR 48692 were similar to those found with the molecularly cloned human neurotensin receptors. Additionally, the intracellular calcium mobilization and the growth of MIA PaCa-2 cells induced by neurotensin receptor agonist were completely inhibited by SR 48692. In conclusion, our results showed that MIA PaCa-2 cells express functional and SR 48692-sensitive-type neurotensin receptors. It is suggested that the neurotensin receptor antagonist SR 48692 may be useful in the treatment of pancreatic cancers that possess this type of neurotensin receptor.

Calcium↗

PubMed1994

Activation of diacylglycerol kinase by carbachol in guinea pig taenia coli.

Changes in diacylglycerol kinase (DG kinase) activity in carbachol (CCh)-stimulated guinea pig taenia coli were investigated. In a mixed micellar assay system, added 1,2-dioctanoyl-sn-glycerol (diC8) and endogenous DG were competitively bound to common DG kinase isozymes from guinea pig taenia coli and phosphorylated, suggesting that diC8 is useful as a probe of agonist effects on DG kinase activity. In phosphorus-32 ([32P]Pi)- and diC8-prelabeled guinea pig taenia coli, diC8 was phosphorylated by DG kinase to [32P]dioctanoyl-phosphatidic acid ([32P]diC8-PA). CCh increased the accumulation of both [32P]diC8-PA and endogenous [32P]phosphatidic acid ([32P]PA) in a time- and dose-dependent manner (0.1-100 microM CCh). CCh-induced increases in [32P]diC8-PA and [32P]PA were inhibited by 1 microM atropine and 3 microM DG kinase inhibitor (R59022). These findings indicated the activation of DG kinase by muscarinic receptor stimulation in guinea pig taenia coli. Therefore, DG kinase activation may play an important role in CCh-induced PA formation. CCh-induced [32P]diC8-PA and [32P]PA accumulation was dependent on intracellular calcium concentrations. However, a KCl-induced increase in intracellular calcium, without receptor stimulation, was ineffective. Moreover, treatment with phorbol ester also increased accumulation of both PA species in KCl-treated tissues. These findings suggest that muscarinic receptor mediated activation of DG kinase may require both an increase in intracellular calcium and PKC activation in guinea pig taenia coli.

Animals↗

PubMed1994

3',3",5',5"-Tetraiodophenolsulfonephthalein is a selective inhibitor of Ca(2+)-pumping ATPase in intracellular Ca2+ store.

3',3",5',5"-Tetraiodophenolsulfonephthalein (I4PSP) stimulated both Ca2+ transient levels and aggregation in response to thrombin in platelets. Ca2+ uptake into skeletal sarcoplasmic reticulum (SR) was inhibited by I4PSP (IC50, 1.8 microM) whereas that of red blood cell ghosts was not affected by it. Furthermore, I4PSP inhibited the SR Ca(2+)-ATPase activity (IC50, 1.1 microM). Kinetic analysis of the inhibitory effects of I4PSP reveals that I4PSP shows an inhibition of noncompetitive and competitive type with respect to low and high concentrations of ATP, respectively. The mode of inhibition by I4PSP is an uncompetitive type with respect to Ca2+. I4PSP decreased the decomposition rate of the phosphorylated enzyme intermediate (EP). The change in the tryptophan fluorescence of SR Ca(2+)-ATPase induced by ATP was reduced by I4PSP indicating inhibition of the EP transition from Ca2E1P to E2P. The concentration-inhibitory response curves for I4PSP in Ca(2+)-ATPase activities and fluorescence changes were closely correlated. These results suggest that I4PSP slows down the structure transition from Ca2E1P to E2P, resulting in inhibition of the Ca(2+)-ATPase activity. On the basis of these results, it is suggested that the stimulation of Ca2+ transient levels in platelets and their aggregation in response to thrombin are due to the inhibition of Ca2+ pump in intracellular Ca2+ stores by I4PSP.

Adenosine Triphosphate↗

PubMed1994

Reduction by NG-nitro-L-arginine of H2O2-induced endothelial cell injury.

1. The effects of three analogues of NG-nitro-L-arginine (L-NOARG) and NG-monomethyl-L-arginine (L-NMMA), inhibitors of nitric oxide (NO) synthase, on hydrogen peroxide (H2O2)-induced endothelial cell injury were studied. 2. Endothelial cell injury was assessed by measuring the release of intracellular lactate dehydrogenase (LDH) and 51Cr. 3. Addition of H2O2 (250-1,000 microM) to endothelial cells induced the release of LDH dose-dependently. The release of LDH was reduced by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 10(-4)-4 x 10(-3) M), L-NOARG (10(-4)-4 x 10(-3) M) and NG-nitro-L-arginine benzyl ester (L-NABE, 10(-4)-4 x 10(-3) M), inhibitors of NO synthase. 4. L-NOARG analogues also reduced H2O2-induced 51Cr release from endothelial cells, while L-NMMA had no effect. 5. The protective effect of L-NAME was not reversed by addition of L-arginine (L-Arg, 1-10 mM). 6. Both L-NAME and L-NMMA completely inhibited L-Arg metabolism to L-citrulline coupled with NO synthesis. 7. These findings suggest that L-NOARG analogues but not L-NMMA reduced H2O2-induced endothelial cell injury, and that these effects may not be related to inhibition of NO production.

Amino Acid Oxidoreductases↗

PubMed1994

Turbidimetric latex agglutination inhibition immunoassay for primidone.

We have developed a quick, highly sensitive immunoassay method for drugs by latex agglutination inhibition. An antiserum against primidone (PRM) was obtained by immunizing rabbits with PRM-bovine serum albumin conjugate. PRM-rabbit serum albumin conjugate sensitized latex was agglutinated with diluted antiserum, and the agglutination was inhibited by free PRM quantitatively. Turbidity of the agglutination suspension was measured by spectrophotometry as absorbance. Larger latex gave higher sensitivity than the smaller, because its agglutination was inhibited more intensely by free PRM. The assay values of this method were correlated well with those obtained by an enzyme immunoassay method.

Animals↗

PubMed1994

The relationship between spontaneous calcium oscillations and cell proliferation in cultured smooth muscle cells.

The relationship between spontaneous Ca2+ oscillations and cell proliferation was investigated in cultured longitudinal muscle cells from guinea pig ileum. BAPTA, caffeine, thapsigargine and La3+ suppressed the spontaneous Ca2+ oscillations and the DNA synthesis at 5.0 mM, 10.0 mM, 15.62 nM and 0.5 mM, respectively, whereas verapamil, nicardipine and ryanodine did not suppress either. However, BAPTA and La3+ did not inhibit the DNA synthesis at 1.25 mM and 0.13 mM, but did suppress the Ca2+ oscillations even at 1.0 mM and 0.1 mM, respectively. These results show that the spontaneous Ca2+ oscillations are not prerequisite for the cell proliferation.

Animals↗

PubMed1994

Bradykinin induces generation of reactive oxygen species in bovine aortic endothelial cells.

We investigated the effects of bradykinin on intracellular oxidative stress in bovine aortic endothelial cells using a hydroperoxide-sensitive fluorescent dye, 2',7'-dichlorofluorescein (DCFH), and a laser scanning confocal microscope. Bradykinin induced an immediate increase in intracellular Ca2+ concentration, and stimulated the oxidation of DCFH in cultured endothelial cells. This bradykinin-induced oxidation of DCFH was inhibited by pretreatment with N-(2-mercaptopropionyl)-glycine (MPG) and 1,3-dimethyl-thiourea (DMTU), scavengers of hydroxyl radical, and the removal of extracellular Ca2+ but was unaffected by NG-nitro-L-arginine or NG-monomethyl-L-arginine, both inhibitors of nitric oxide (NO) synthase. On the other hand, pretreatment with indomethacin and aspirin, inhibitors of cyclooxygenase, inhibited bradykinin-induced oxidation of DCFH. These findings suggest that bradykinin increases intracellular Ca2+ and stimulates the generation of hydroxyl radical-like reactive oxygen species (scavenged by MPG or DMTU) via the cyclooxygenase pathway but not via the reaction of NO and superoxide anion.

Amino Acid Oxidoreductases↗

PubMed1994

All-or-none like responses in increment of cytoplasmic free calcium concentrations to histamine in single smooth muscle cells of guinea pig trachea.

Single smooth muscle cells were isolated from guinea pig trachea and cultured for 48 hours. The cells were then loaded with a fluorescent-free calcium indicator, fluo-3. Concentrations of cytoplasmic-free calcium ([Ca2+]i) were determined by using a confocal laser scanning fluorescence imaging system. Cells exposed to histamine at concentrations less than 1.0 microM did not indicate any changes of the fluorescence intensities, but stayed at the basal level of [Ca2+]i. Cells exposed to histamine at a concentration in the range of 1.5 to 10 microM indicated marked increases in [Ca2+]i. A further increase in [Ca2+]i by application of higher concentrations of histamine was not observed. The threshold concentration of histamine to increase [Ca2+]i and peak [Ca2+]i varied from cell to cell. In addition, half-maximal response time was shortened with increasing concentrations of histamine from 1.5 to 100 microM. These results indicate that [Ca2+]i responses to histamine is an all-or-none type in each cell. The heterogeneity in the required threshold concentration of histamine to increase in [Ca2+]i and the concentration dependency in half-maximal response time of histamine-induced [Ca2+]i increase may be related to the graded responses of histamine-induced contractions in preparations of the tracheal tissue.

Aniline Compounds↗

PubMed1994

Stimulation by hydrogen peroxide of L-arginine metabolism to L-citrulline coupled with nitric oxide synthesis in cultured endothelial cells.

The effect of hydrogen peroxide on metabolism of L-arginine to L-citrulline in the biosynthesis of nitric oxide was investigated in bovine aortic endothelial cells. Addition of hydrogen peroxide (1-10 mM) to endothelial cells increased L-citrulline formation from L-arginine in a dose-dependent manner. Stimulation of L-citrulline formation was prevented by catalase (20 micrograms/ml), a hydrogen peroxide scavenger, but not by superoxide dismutase (SOD, 100 micrograms/ml), a superoxide anion scavenger. Pretreatment with NG-nitro-L-arginine (10(-5) M) and NG-methyl-L-arginine (10(-4) M), potent inhibitors of nitric oxide synthase, also inhibited L-citrulline formation induced by hydrogen peroxide. Moreover, hydrogen peroxide increased intracellular Ca2+ concentrations, and the removal of extracellular Ca2+ reduced the hydrogen peroxide-induced formation of L-citrulline. These findings show that hydrogen peroxide increases the intracellular Ca2+ concentration and stimulates the formation of L-citrulline from L-arginine coupled with nitric oxide synthesis in cultured endothelial cells.

Animals↗

PubMed1994

[Effect of epinephrine added to spinal anesthesia with lidocaine and tetracaine].

The effect of epinephrine added to the solution of lidocaine and tetracaine for spinal anesthesia was investigated in patients undergoing elective surgery of lower extremities. Thirty patients received 3ml of 2% lidocaine and 0.4% tetracaine and 30 patients received the solution with 0.1 mg of epinephrine added. A lumbar puncture was performed at the L2-3 interspace, using a midline approach with a 25-gauge spinal needle. Mean highest level of pinprick analgesia was Th6.1 without epinephrine and Th4.4 with epinephrine, and mean time for regression to Th10 was 2.3 hours without epinephrine and 3.6 hours with epinephrine. Progression of analgesia level was significantly faster and prolongation of duration was significant greater after adding epinephrine. No severe complications were found in any patients. We concluded that adding 0.1 mg of epinephrine to 3 ml of 2% lidocaine and 0.4% tetracaine could produce clinically useful prolongation of spinal analgesia.

Adolescent↗

PubMed1993

Reduction in the numbers of muscarinic receptors by an endogenous protein.

The soluble fraction from the ileal longitudinal muscle of guinea pigs was examined for the presence of an endogenous modulator of muscarinic receptors. In the presence of the soluble fraction, the binding of [3H]quinuclidinyl benzilate to the membranes from the tissue was inhibited in a concentration-dependent manner. The inhibitory activity in the soluble fraction was heat stable, but was inactivated by trypsin treatment. Several protease inhibitors had no effect on the inhibitory activity. These results suggest the existence of an endogenous protein that inhibits the binding of the muscarinic ligand to the receptor. Ultrafiltration demonstrated that the protein factor had a molecular mass of more than 10,000 Da. Saturation binding and dissociation kinetic experiments indicate neither a competitive nor allosteric mode of inhibitory action and suggest that an irreversible block or internalization of muscarinic receptors is induced by the endogenous protein.

Allosteric Regulation↗

PubMed1993

[Isolation, configuration and contractile responses of single smooth muscle cells].

In studies on the intrinsic contraction mechanisms of smooth muscle, various factors such as cell-to-cell interaction, penetration of chemicals to the trigger regions, or extracellular spaces in the tissue may influence the results. The use of single smooth muscle cells in such investigations may help to eliminate these factors. Single smooth muscle cells can be isolated from guinea pig taenia coli by digesting the minced tissue with a combination of collagenase and soybean trypsin inhibitor. The cells are spindle shaped, 100-200 microns in length and 10 microns in diameter. Three kinds of techniques for determination of contractile responses of single smooth muscle cells have been established: 1) fixation method, 2) perfusion method, and 3) capillary adhesion method. Using these techniques, the cells appeared to be contracted in a dose-dependent manner (graded response), while another mode of the contractile response, the "all-or-none response", has also been proposed. Scanning and transmission electron micrographs of the single cells revealed several evaginations of various sizes and shapes on the surface and electron dense bodies at the neck of the evaginations. ED50 obtained with the single cells, prepared from taenia coli of guinea pigs with collagenase in the presence of trypsin inhibitor was similar to that obtained with the intact tissue. Digestion of the tissue with highly purified collagenase and papain yields a large number of single cells with higher sensitivity to agonists. Characteristics of cells isolated from ileal longitudinal muscle of guinea pig are similar to those of cells isolated from taenia coli. The magnitude of contraction and sensitivity to acetylcholine were different in each cell. Incubation of isolated tissues with various concentrations of agonists followed by measurement of cell length in the tissue showed that the heterogeneous responses of the cells were intrinsic characteristics of smooth muscle cells and not due to damage incurred during the isolation procedure. Since isolated smooth muscle cells possess contractility, these might preserve the characteristics of smooth muscle, so they can be used for smooth muscle research. It must be considered, however, that each cell in the smooth muscle tissue has different contractility.

Acetylcholine↗

PubMed1993

Spontaneous oscillations of cytoplasmic free calcium ion concentration in cultured smooth muscle cells from guinea pig ileum.

The cytoplasmic free calcium ion concentration ([Ca2+]i) of cultured guinea pig ileum longitudinal muscle cells loaded with a fluorescent [Ca2+]i indicator, fura-2, was measured by digital ratio imaging microscopy. Spontaneous [Ca2+]i oscillations were observed in 25% to 80% of the cells, which differed with the batches of the cultured cells after 5 to 8 days in culture. The frequency and amplitude of the [Ca2+]i oscillations in each individual cell were usually regular, but heterogeneity between neighboring cells was observed. The spontaneous [Ca2+]i oscillations were also observed even after incubation of the cells under a serum-free condition for 72 hr. Exchange of extracellular solution to Ca(2+)-free solution containing EGTA or BAPTA immediately stopped the [Ca2+]i oscillations. The ratio of the oscillating cells was dependent on the extracellular calcium ion concentration ([Ca2+]o); and heterogeneity in the range of the [Ca2+]o to generate the [Ca2+]i oscillations was observed. An inorganic Ca(2+)-antagonist, LaCl3, immediately suppressed the [Ca2+]i oscillations, but the treatment with verapamil or nicardipine, Ca(2+)-channel blockers, did not have any effect on the [Ca2+]i oscillations. An inhibitor of the intracellular Ca2+ pump, thapsigargin, induced a transient increase in [Ca2+]i and then inhibited the spontaneous [Ca2+]i oscillations. Neomycin, a compound known to inhibit phosphoinositide turnover, inhibited the [Ca2+]i oscillations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Heterogeneous contractile responses of single smooth muscle cells from guinea pig ileum.

Cells of guinea pig ileal longitudinal muscle layer were dispersed by treating the minced tissue with highly purified collagenase and papain. The cells were spindle shaped, 100 to 150 microns long and 5 to 10 microns wide. Contractility of the dispersed cells was determined by "cell adhesion method" resulting that the cells were contracted by carbachol in a dose-dependent manner, but sensitivity and degree of the contraction were different in each cell. Binding assay method resulted that Kd values did not change by treatment with collagenase and papain. These results indicate that contractility of each cell in the tissue is originally different and dispersion of the cells does not affect on the cell contractility.

Animals↗

PubMed1993

Inhibition by methylene blue of the L-arginine metabolism to L-citrulline coupled with nitric oxide synthesis in cultured endothelial cells.

The effect of methylene blue on the metabolism of L-arginine to L-citrulline coupled with nitric oxide synthesis in cultured endothelial cells was investigated. The addition of the calcium ionophore ionomycin (10(-8)-10(-5) M) to endothelial cells stimulated L-citrulline formation from L-arginine. Ionomycin-stimulated L-citrulline formation was inhibited by NG-nitro-L-arginine (10(-6)-10(-4) M), a potent inhibitor of nitric oxide synthase. These results indicate that ionomycin-stimulated L-citrulline formation was coupled to nitric oxide synthesis. Therefore, L-citrulline formation from L-arginine was used as a marker for nitric oxide synthesis. Methylene blue (10(-4)-10(-3) M) inhibited ionomycin-stimulated L-citrulline formation in bovine aortic endothelial cells. Moreover, the formation of L-citrulline by the particulate fraction obtained from bovine cultured endothelial cells was also inhibited by methylene blue concentrations in excess of 10(-5) M. Although the addition of methylene blue to various tissues has been reported to release superoxide anions (Wolin et al., 1990; Marczin et al., 1992), inhibition of L-citrulline formation by methylene blue was not affected by the presence of superoxide dismutase (100 micrograms/mL) in either cultured endothelial cells or the particulate fraction. These findings suggest that methylene blue is a direct inhibitor of nitric oxide synthase in bovine aortic endothelial cells.

Amino Acid Oxidoreductases↗

PubMed1993

Effect of diacylglycerol kinase inhibitor, R59022 on cytosolic free calcium level and force development in guinea pig taenia coli.

We previously described that carbachol (CCh) increased intracellular phosphatidic acid (PA) in guinea pig taenia coli and the increase was inhibited by diacylglycerol (DG) kinase inhibitor, R59022. The present study was conducted to clarify the role of DG kinase in CCh-induced increase in cytosolic free calcium and force development. Application of CCh to taenia coli induced transient increase in calcium level and contraction followed by sustained and lower calcium level and smaller contraction, and R59022 inhibited the latter responses specifically. The sustained responses were also evoked by 50 mM KCl, but these responses were slightly inhibited by R59022. Inhibition of calcium influx reduced responses to CCh but not KCl. Therefore, we consider that the sustained contraction induced by CCh is attributed to activation of DG kinase which generates PA and accelerates calcium influx.

Animals↗