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Biomedical subjects

K Kakinuma

Publications and source records attributed to K Kakinuma.

At least 91 records · Page 5Linked to original sources
PubMed1986

Effect of saturated and unsaturated fatty acids on the oxidative metabolism of human neutrophils. The role of calcium ion in the extracellular medium.

The ability of fatty acids to stimulate the generation of superoxide anion (O2-) by human neutrophils was investigated with respect to their Krafft points. Saturated (myristic acid) and unsaturated (elaidic and oleic acid) induced a marked O2- generation and release from human neutrophils at pH 7.4 in the absence of Ca2+, while 0.3 mM Ca2+ inhibited both myristic acid and elaidic acid-induced O2- release. [14C]Myristic acid association with neutrophils was reduced by addition of Ca2+, whereas oleic acid association was not affected. When the pH of the reaction mixture was lowered to 6.4, 0.6 mM Ca2+ did not inhibit the O2- generation by human neutrophils. These results indicate that the inhibitory effect of Ca2+ on the fatty acid-induced O2- generation might be due to the ionic interaction between the carboxyl group of the fatty acid and Ca2+. Furthermore, 11-methyltridecanoic acid, a branched isomer of myristic acid, which showed the low Krafft point even in the presence of Ca2+, stimulated O2- generation by human neutrophils not only in the absence but also in the presence of 0.6 mM Ca2+. The effect of Ca2+ on the fatty acid-induced O2- generation by neutrophils was discussed with reference to its possible relationship to the Krafft point.

Calcium↗
PubMed1986

Electron spin resonance studies on a flavoprotein in neutrophil plasma membranes. Redox potentials of the flavin and its participation in NADPH oxidase.

Plasma membrane fractions of stimulated and resting cells were isolated from pig blood neutrophils. The midpoint redox potential (Em) of the membrane-bound flavin was determined potentiometrically by analysis of the flavin free-radical signal by electron spin resonance (ESR) spectroscopy. In both stimulated and resting cells, a peak position of the titration curve gave an Em value of -280 mV at pH 7.0 (Em7). The flavin free radical showed an ESR spectrum at g = 2.004 with a peak to peak width of 19 G, which indicates that the redox intermediate is a neutral semiquinone. Redox titrations were anaerobically examined at 25 degrees C with NADPH in place of dithionite. Addition of NADPH to plasma membranes of stimulated cells resulted in a rapid change in potential, accompanied by the formation of the ESR signal of flavin free radical. Computer simulation of the titration points gave an ambient midpoint potential of -280 mV (Em7). In contrast, those of resting cells showed a very slow change in potential and no g = 2.00 signal formation. Power saturation behavior of the ESR signal showed a marked difference between those of stimulated and resting cells. ESR characteristics of the flavin are discussed in relation to the membrane-bound NADPH oxidase.

Animals↗
PubMed1986

Hypertonic glycerol induces a respiratory burst in leukocytes.

Exposure to hypertonic glycerol induced cyanide-insensitive oxygen consumption and formation of superoxide anion (O-2) in leukocytes such as porcine blood polymorphonuclear leukocytes, guinea pig peritoneal leukocytes and guinea pig alveolar macrophages. Generation of O-2 occurred after a short lag time, remained maximal for a certain time and then stopped. Its termination was not due to cell damage, since cells exposed to glycerol did not release cytosolic enzymes such as lactate dehydrogenase and exhibited a subsequent respiratory burst upon addition of other stimulators such as myristic acid and phorbol myristate acetate. The period of O-2 generation increased linearly as a function of the glycerol concentration; cells exposed to 20% (v/v) glycerol produced O-2 for 10 min. The maximal velocity of O-2 generation also increased with the concentration of glycerol, reaching a plateau at 10% glycerol. Membrane vesicles isolated from the cells exposed to 20% glycerol showed high activity of NADPH-dependent O-2 generation as compared to those of unexposed cells. Activation of leukocytes by glycerol was not accompanied by degranulation, unlike stimulation by phagocytosis. A marked change in shape of the cell membrane of glycerol-treated cells was observed by light and scanning electron microscopies.

Animals↗
PubMed1986

Is cytochrome b558 translocated into the plasma membrane from granules during the activation of neutrophils?

Two laboratories (Borregaard et al. (1984) J. Biol. Chem. 259, 47; Ohno et al. (1985) J. Biol. Chem. 260, 2409) have reported that a b-type cytochrome (b558) was translocated into plasma membranes from specific granules in activated neutrophils. In an attempt to examine the cytochrome b translocation, porcine neutrophils were activated by treatment with surface-active agents such as myristate (MA) and phorbol myristate acetate (PMA), and then the postnuclear supernatants of both activated and unactivated cells were fractionated by Percoll density gradient centrifugation with a Zonal rotor. In activated neutrophils, high O2- generating activity was found in the plasma membrane fraction, which showed a peak of Na, K-ATPase activity as a marker enzyme. Cytochrome b558 was recovered 74 to 78% in the plasma membrane fraction and 14 to 16% in granules in either activated or unactivated cells. No change in specific content of cytochrome b558 was observed in plasma membranes before and after activation of cells. Furthermore, in both activated and unactivated cells, vitamin B12-binding protein, a specific granule marker, was mainly found in the bottom fractions and scarcely at all in plasma membranes. These results suggest that no translocation of cytochrome b558 occurs during activation of neutrophils.

Animals↗
PubMed1985

Effect of cetiedil on the superoxide-generating system of porcine neutrophils.

Cetiedil, alpha-cyclohexyl-3-thiopheneacetic acid 2-(hexahydro-1H-azepin-1-yl)-ethyl ester, was found to inhibit the generation of superoxide (O2-) by porcine neutrophils exposed to various stimulators. The concentration of cetiedil required for 50% inhibition was about 45 microM when neutrophils were stimulated by phorbol myristate acetate. Cetiedil not only decreased the rate of generation of O2-, but prolonged the lag time prior to the production of O2-. The inhibitory effect of cetiedil on the O2(-)-generating activity of the NADPH oxidase in the membrane vesicles was less than that on whole cells; the concentration of cetiedil necessary for 50% inhibition was about 250 microM. To study the mechanism of cetiedil's effect on the membrane, the transmembrane potential of neutrophils and the intracellular free Ca2+ concentration were monitored by using fluorescence probes, diS-C3-(5), and quin-2, respectively. Cetiedil caused depolarization of the membrane potential and increased the intracellular free Ca2+. These results indicate that integrity of ionic distribution is necessary to activate the O2(-)-generating system of neutrophils.

Animals↗
PubMed1985

Effects of cetiedil on the oxidative metabolism of activated polymorphonuclear leucocytes.

Cetiedil, alpha-cyclohexyl-3-thiopheneacetic acid 2-(hexahydro-lH-azepin-l-yl)-ethyl ester, was found to specifically suppress oxygen uptake by polymorphonuclear leucocytes (PMN) that were exposed to myristate or heat-killed E. coli. The chemical had no effect on the basal respiration rate of PMN in the resting state. Inhibition of oxygen uptake by cetiedil was proportionate to the degree of inhibition of the generation of O-2 and H2O2. It was also found that cetiedil suppressed the rate of the phagocytosis by PMN of opsonized oil droplets. Cetiedil had no effect on subcellular NADPH oxidase, an enzyme responsible for the respiratory burst that is activated by the perturbation of PMN plasma membrane with phagocytable particles or stimulators such as myristate. These results suggest that cetiedil affects the trigger mechanism of the plasma membrane to inhibit the activation of NADPH oxidase.

Animals↗
PubMed1984

Functional maturation of membrane potential changes and superoxide-producing capacity during differentiation of human granulocytes.

The alterations of stimulus-induced membrane potential changes, superoxide (O2-)-producing capacity and phagocytic activity during differentiation of human granulocytes were investigated in the human leukemia cell lines HL-60 and KG-1 differentiating in vitro and in human leukemic granulocytes obtained from chronic myelogenous leukemia patients. HL-60 cells incubated with dimethyl sulfoxide or with retinoic acid showed progressively increasing O2- production as well as membrane potential changes (depolarization) on contact with phorbol myristate acetate or the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine, with a concomitant increase in the proportion of mature cells of the granulocytic type. Phagocytosis of latex particles, yeast, and oil droplets appeared 24 h after incubation with dimethyl sulfoxide and anteceded the increment of O2- production and membrane potential changes, both of which appeared concomitantly 3 d after incubation with dimethyl sulfoxide. Similar findings were observed when immature and mature granulocytes obtained from chronic myelogenous leukemia patients were stimulated by phorbol ester, the chemotactic peptide, or calcium ionophore A23187, and the amount of O2- production was parallel to the magnitude of membrane potential changes. HL-60 and KG-1 cells incubated for 1-6 d with phorbol myristate acetate showed neither O2- production nor membrane potential changes on contact with phorbol ester, chemotactic peptide, or A23187, although such cells resembled macrophages morphologically, and their phagocytic activity was significantly increased. O2- production and membrane potential changes in normal granulocytes induced by phorbol ester, chemotactic peptide and A23187 were inhibited by 2-deoxyglucose. These findings indicate that the O2--producing system and the system provoking membrane potential changes may develop concomitantly as human granulocytes mature and differentiate, and that the development of these systems and of phagocytic activity may be independently regulated.

Adult↗
PubMed1983

Essential requirement of magnesium ion for optimal activity of the NADPH oxidase of guinea pig polymorphonuclear leukocytes.

The NADPH-dependent O2-(H2O2)-forming oxidase-rich plasma membranes were purified from myristate (MA)-activated polymorphonuclear leukocytes using a Percoll-density gradient method. The specific activity of the enzyme in the plasma membrane fraction was twelve times higher than that in the cells. Studies on the effect of divalent cations and chelators on the O2- and H2O2 generating activity of the oxidase showed that Mg2+, but not Ca2+, enhanced the activity significantly. Zn2+, on the other hand, was slightly inhibitory to the oxidase activity. EDTA markedly inhibited the oxidase activity whereas EGTA enhanced it. The optimal oxidase activity was seen in the presence of mumolar concentrations of Mg2+ and reached a maximum at Mg2+ concentrations of 40-50 microM. The addition of Mg2+ resulted in a decrease in the apparent Km of the oxidase for NADPH from 40 microM to 25 microM and an increase in apparent Vmax by 1.5 times. These results suggest that Mg2+ enhances both NADPH binding and catalytic activities of the oxidase.

5'-Nucleotidase↗
PubMed1983

Evidence that NADPH is the actual substrate of the oxidase responsible for the "respiratory burst" of phagocytosing polymorphonuclear leukocytes.

The relationship between glucose metabolism and the "respiratory burst" of phagocytosing polymorphonuclear leukocytes (PMN) was studied in a Renex 30-treated cell system of guinea pig PMN by a polarometric technique. Phagocytosing PMN were treated with a detergent (Renex 30) and recovery of respiratory activity was examined by addition of various concentrations of NADP and glucose-6-phosphate (G6P) to determine the availability of endogenously formed NADPH via the hexose monophosphate (HMP) pathway. The oxygen uptake by phagocytosing PMN ceased after the treatment with Renex 30 and was restored by the addition of NADP and G6P. Furthermore, the restoration of oxygen uptake was linearly proportional to the rate of NADPH formation on increase in either NADP or G6P concentration. Resting PMN showed no respiratory activity even in the presence of excess NADP and G6P, in which NADPH was formed at the same rate as in phagocytosing PMN. In a parallel experiment, recovery of respiratory activity was examined in the same system by addition of NAD and glyceraldehyde-3-phosphate (G3P) in that order to clarify whether the respiratory enzyme can utilize NADH formed via the glycolytic pathway. In contrast to the results in the NADPH-forming system, the addition of NAD and G3P induced slight oxygen uptake of Renex 30-treated PMN, but there was no difference in the oxygen uptake between resting and phagocytosis-activated PMN. The results indicated that the primary oxidase responsible for the "respiratory burst" is NADPH oxidase, and that its activity is coupled with glucose oxidation via the HMP pathway without the participation of other metabolic pathways such as glycolysis.

Animals↗
PubMed1983

Activation of guinea pig polymorphonuclear leukocytes with soluble stimulators leads to nonrandom distribution of NADPH oxidase in the plasma membrane.

Guinea pig polymorphonuclear leukocytes (PMN) were briefly activated with soluble stimulators such as sodium myristate (SM) or phorbol myristate acetate (PMA) and then disrupted by the nitrogen cavitation method to study the subcellular distribution of NADPH oxidase, which is responsible for O2 - generation. Fc-receptor and 5'-nucleotidase activities were measured as plasma membrane markers. 1) The homogenate was first fractionated by differential centrifugation. The O2- -generating activity of PMN activated either by SM or PMA was recovered in a 2 X 10(4) g pellet which contained a large amount of granules and about 50% of the plasma membrane markers, but not in a 1 X 10(5) g pellet which consisted of plasma membranes and few granules. 2) Further separation of the 2 X 10(4) g pellet from PMA-activated PMN was attempted by an iso-osmotic Percoll density gradient centrifugation. The O2- -generating activity was recovered in light fractions in which plasma membrane markers were found, but neither in specific nor in azurophil granules. The 1 X 10(5) g pellet showed a similar distribution of the plasma membrane markers to that of the 2 X 10(4) g pellet, except that the peak of the O2- -generating activity was much smaller on an identical density gradient. The results showed that NADPH oxidase is located in the plasma membranes precipitated by centrifugation at 2 X 10(4) X g but not in the ones precipitated at 1 X 10(5) X g. The results suggest that the plasma membrane of activated PMN has a mosaic distribution of NADPH oxidase.

Animals↗
PubMed1982

An Fc-receptor activity of plasma membranes from guinea-pig peritoneal polymorphonuclear leucocytes.

Plasma membranes prepared from guinea-pig peritoneal polymorphonuclear leucocytes showed an immune-complex-binding activity that corresponded well with the activity in intact cells. The characteristics of this activity were reversible binding, dependence on the Fc portion of antigen-complexed IgG (immunoglobulin G), competition with aggregated IgG and independence from energy metabolism. These results support the conclusion that the binding activity found in the isolated plasma membranes is an Fc-receptor activity of guinea-pig peritoneal polymorphonuclear leucocytes. The activity showed Kd = 6.7 x 10(-8) M-IgG and maximum binding of 17 pmol of IgG/mg of membrane protein when measured with an immune complex of alpha-amylase and homologous guinea-pig anti-(alpha-amylase) IgG. Inhibition of the Fc-receptor activity by a series of various salts indicated the contribution of the hydrophobic interaction to the binding. Inhibitory effects of salts or metal-chelating reagents on the Fc-receptor activity were also observed on superoxide generation by these cells induced by the immune complex, suggesting a role of the Fc receptor as the immune-complex-binding site responsible for the initiation of superoxide generation.

Animals↗