Biomedical subjects

C Inagaki

Publications and source records attributed to C Inagaki.

At least 73 records · Page 4Linked to original sources

PubMed1991

[Individual differences in image and pulse-wave responses elicited by listening to music].

This study was undertaken to clarify individual differences in psycho-physiological responses observed in subjects listening to music. Forty-five healthy females listened to the third movement of Mozart's "Eine Kleine Nachtmusik" via a biaural headphone at 69.4 dB(A) in Leq and 83.6 dB(A) in Lmax. This was undertaken twice with an interval of six days between sessions. Pulse-waves were recorded continuously before, during, and after listening by using a photoelectric plethysmograph. The psychological image each listener had of the music was measured immediately after listening by the SD method composed of fifteen scales with five rating points. The following results were obtained: 1) The pulse-wave height initially became low right after the onset of listening, though the degree of the decrement weakened in the second trial. Spectral analysis of pulse-waves revealed that the power percentage in the low frequency-bands below 0.3912 Hz grew markedly and that in the frequency-bands above 0.4238 Hz it dwindled during and after listening at the first trial. However, these changes of power percentage weakened in the second trial. 2) The image of the music being listened to changed significantly in 11 scales from the first trial to the second trial. 3) Subjects having a previous experience of listening to the music showed smaller image changes and responses in pulse-waves in the second trial than subjects having no such experience. 4) Previous experience of learning any music and the amount of contact with any music were not related to the image changes and pulse-wave responses in the second trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Ethacrynic acid-induced convulsions and brain noradrenaline in mice.

The intracerebroventricular injection of ethacrynic acid (a 50% convulsive dose; 50 micrograms/mouse) accelerated brain noradrenaline turnover and decreased noradrenaline contents. The decrease in noradrenaline contents was antagonized by 2-amino-5-phosphonovalerate but not by diazepam. Both 2-amino-5-phosphonovalerate and diazepam suppressed the incidence of ethacrynic acid-induced convulsions while reserpine, alpha-methyl-para-tyrosine or FLA-63 augmented it. The results suggest that stimulation by ethacrynic acid of excitatory amino acid neurons enhances-noradrenergic neuronal anticonvulsive activity.

Animals↗

PubMed1990

Effects of inhibitors of protein kinase C and Na+/H+ exchange on alpha 1-adrenoceptor-mediated inotropic responses in the rat left ventricular papillary muscle.

1. Alpha 1-adrenoceptor stimulation of rat left ventricular papillary muscle produced a triphasic inotropic response: an initial transient positive inotropic effect (PIE) followed by a transient negative inotropic effect (NIE) and a sustained PIE. 2. The protein kinase C inhibitor, staurosporine, at concentrations ranging from 30 nM to 100 nM inhibited the sustained PIE, but had no significant effect on the transient PIE and NIE. 3. H-7, 1-(5-isoquinoline sulphonyl)-2-methylpiperazine, a less specific inhibitor of protein kinase C than staurosporine, at a concentration of 100 microM inhibited both the transient NIE and the sustained PIE without affecting the transient PIE. 4. Amiloride, an inhibitor of Na+/H+ exchange, at concentrations ranging from 0.1 mM to 1 mM inhibited the sustained PIE and, at higher concentrations, also inhibited the transient NIE. 5. An amiloride analogue, 5-(N-methyl-N-isobutyl)amiloride (MIBA), inhibited only the sustained PIE with an IC50 of 0.3 microM which is approximately two orders of magnitude lower than amiloride. 6. The receptor-linked stimulation of Na+/H+ exchange through protein kinase C activation may be a mechanism for alpha 1-adrenoceptor-mediated sustained PIE.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1989

An ATP-driven Cl- pump in the brain.

EDTA-treated microsomes prepared from rat brain mainly consisted of sealed membrane vesicles 200-500 nm in diameter and were rich in both Cl- -ATPase and Na+,K+-ATPase activities. Such Cl- -ATPase-rich membrane vesicles accumulated Cl- in an ATP-dependent and osmotically reactive manner in the presence of 1 nM ouabain. The Cl- uptake was maximally stimulated by ATP with a Km value of 1.5 mM; GTP, ITP, and UTP partially stimulated Cl- uptake, but CTP, beta, gamma-methylene ATP, ADP, and AMP did not. The ATP-dependent Cl- uptake was accelerated by an increase in the medium Cl- concentration with a Km value of 7.4 mM. Such stimulation of Cl- uptake by ATP was dependent on the pH of the medium, with an optimal pH of 7.4, and also on the temperature of the medium, with an optimal range of 37-42 degrees C. Ethacrynic acid dose dependently inhibited the ATP-dependent Cl- uptake with a concentration for half-maximal inhibition at 57 microM. N-ethylmaleimide (0.1 mM) completely inhibited and sodium vanadate (1 mM) partially inhibited the ATP-dependent Cl- uptake. The membrane vesicles did not accumulate H+ in the Cl- uptake assay medium. The ATP-dependent Cl- uptake profile agreed with that of Cl- -ATPase activity reported previously (Inagaki, C., Tanaka, T., Hara, M., and Ishiko, J. (1985) Biochem. Pharmacol. 34, 1705-1712), and this strongly supports the idea that Cl- -ATPase in the brain actively transports Cl-.

Adenosine Triphosphatases↗

PubMed1989

Intracerebroventricular injection of ethacrynic acid induces status epilepticus.

The intracerebroventricular (i.c.v.) injection of ethacrynic acid to mice at a dose of more than 25 micrograms induced repeated tonic-clonic convulsions with subsequent death. Ethacrynic acid was more potent than other loop diuretics such as furosemide and bumetanide. Diazepam and 2-amino-5-phosphonovaleric acid notably reduced both the incidence of convulsion and the lethality seen after ethacrynic acid administration. Both phenobarbital and ketamine suppressed the incidence of convulsions but not the lethality. Without effects on the incidence of convulsions or lethality, dextromethorphan prolonged, while phenytoin or atropine shortened, the time to the onset of convulsion. Neither ethosuximide, carbamazepine, nor muscimol had a significant effect on the responses to ethacrynic acid. The present findings indicate that i.c.v. injected ethacrynic acid shows strong convulsive activity, probably due to impairment of Cl- transport processes, concomitant with enhancement of excitatory amino acid activity in the brain.

Animals↗

PubMed1989

ATP-dependent and DCCD-insensitive Cl- uptake by membrane vesicles from the rat brain plasma membrane fractions.

ATP-dependent Cl- uptake by membrane vesicles from the rat brain plasma membrane fractions was not affected by the addition of 40 mM of K+, Na+ or HCO3- to the assay medium. Na+ and K+ did not alter the uptake even in the presence of a K+ ionophore, valinomycin (10 microM), or a H+/K+ exchanger, nigericin (10 microM), whereas in the presence of both of these ionophores, K+, but not Na+, reduced the Cl- uptake. Inhibitors of proton pump activity, N,N'-dicyclohexylcarbodiimide (1 mM) and 5-(N,N-hexamethylene)amiloride (40 microM), however, did not affect the Cl- uptake. These findings suggest the presence of a primary Cl- transport system probably associated with passive H+ flux in the brain plasma membranes.

Adenosine Triphosphate↗

PubMed1989

ATP-dependent H+ transport in synaptosomal membrane vesicles of the rat brain.

H+ transport into synaptosomal membrane vesicles of the rat brain was stimulated by ATP and to a lesser extent by GTP, but not by ITP, CTP, UTP, ADP, AMP or beta, gamma-methylene ATP. ATP at concentrations up to 200 mM concentration-dependently stimulated the rate of H+ transport with a Km value of 0.6 mM, but at higher concentrations of this nucleotide the rate decreased. Other nucleotides such as CTP, UTP, GTP and AMP, or products of ATP hydrolysis i.e. ADP and Pi also reduced the ATP-stimulated H+ transport. The inhibition by GTP and ADP was not affected by the ATP concentration. These findings suggest that plasma membranes of nerve endings transport H+ from inside to outside of the cells utilizing energy from ATP hydrolysis, and that this transport is regulated by the intracellular concentration of nucleotides and Pi on sites other than those involved in substrate binding.

Adenosine Triphosphate↗

PubMed1989

[Effect of ethanol on synaptosomal membrane potential in the rat brain].

The membrane potential of rat brain synaptosomes was depolarized by ethanol at concentrations of over 0.8-1.6%. This ethanol-induced depolarization was augmented by 4-aminopyridine (4-AP) or the gluconate- -medium, but not affected by tetrodotoxin, choline-Cl, NH4Cl, picrotoxin, ethacrynic acid, furosemide or SCN- -medium. The ethanol-induced depolarization was augmented by 4-AP in Cl- - or gluconate- -medium, but not in SCN- -medium. These findings suggest that ethanol depolarizes the synaptosomal membrane potential through potassium and anion-related mechanisms, probably through potassium channels.

4-Aminopyridine↗

PubMed1988

Effects of phospholipases on Cl-ATPase in the rat brain.

We investigated the effects of phospholipases on the activity of microsomal Cl-ATPase in the rat brain, in reference to those on the activities of Na,K-ATPase and anion-insensitive Mg-ATPase. In the presence of phospholipase A2 or phospholipase C, which almost completely hydrolyzed microsomal phosphoglycerides, the activities of Cl-ATPase and Na,K-ATPase were decreased to 8-50% of the control, but anion-insensitive Mg-ATPase activity was not altered. On the other hand, with sphingomyelinase treatment, only anion-insensitive Mg-ATPase was slightly inactivated. On the addition of phospholipids (phosphatidylserine (PS), phosphatidylinositol (PI) and microsomal phospholipid mixture), Cl-ATPase activity slightly recovered only with PI, while Na,K-ATPase activity partially recovered with either phospholipid. These data suggest that Cl-ATPase requires intact membrane lipid conformation and especially PI for its maximal activity.

Adenosine Triphosphatases↗

PubMed1988

ATP-dependent Cl- uptake by plasma membrane vesicles from the rat brain.

Uptake of Cl- by plasma membrane vesicles from the rat brain was stimulated by ATP at 37 degrees C, but not by beta, gamma-methylene ATP or at 0 degrees C. The addition of Triton X-100 or sucrose to the incubation medium diminished the ATP-stimulated Cl- uptake, suggesting that Cl- was transported across the membranes into the intravesicular space. This ATP-stimulated Cl- uptake was not affected by 1 mM ouabain. 1 microM oligomycin, 0.1 mM gamma-aminobutyric acid or 0.1 mM picrotoxin. Thus, non-mitochondrial ATP-driven Cl- transport through a system other than Na, K-ATPase or Cl- channels occurs in neuronal plasma membrane vesicles.

Adenosine Triphosphatases↗

PubMed1988

Proteolytic digestion of Cl(-)-ATPase in rat brain synaptosomes.

Upon tryptic digestion of synaptosomes, ATPase activities decreased in the order of Cl(-)-ATPase greater than or equal to Na+,K+-ATPase greater than anion-insensitive Mg2+-ATPase. Upon synaptosome treatment with hypotonic solution, Cl(-)-ATPase or anion-insensitive Mg2+-ATPase was slightly inactivated, while Na+,K+-ATPase underwent a much larger degree of inactivation. ATP-Mg inhibited the ATPase digestion in the hypotonic-solution-treated synaptosomes in a concentration-dependent manner, but not in the untreated synaptosomes. These results suggest that trypsin-digestible site of Cl(-)-ATPase are present on both sides of the synaptosomal plasma membrane, and the ATP-Mg binding site of the enzyme is located on the inner surface of the membrane.

Adenosine Triphosphatases↗

PubMed1988

[Effect of NH4+ on synaptosomal membrane potential in the rat brain].

The effect of NH4+ on synaptosomal membrane potential was examined using rat brains. The membrane potential was measured by the rhodamine 6G fluorescence method. Both NH4+ diffusion potential (NH4+-potential) and K+ diffusion potential (K+-potential) were observed in the synaptosomes. Upon replacement of medium Cl- with SCN-, both K+- and NH4+-potentials depolarized. On the other hand, replacement of medium Cl- with gluconate resulted in the hyperpolarization of K+-potential, but not of NH4+-potential. Ethacrynic acid (0.3 mM), a Cl- -ATPase inhibitor, depolarized both K+(Cl-)- and NH4+ (Cl-)-potentials. In the presence of ethacrynic acid, both of the potentials were further depolarized by replacement of medium Cl- with SCN-, but not with gluconate-. Picrotoxin (5 mM), a Cl- channel inhibitor, did not significantly affect either K+- or NH4+-potential. In the presence of picrotoxin, replacement of medium Cl- with SCN- depolarized both K+- and NH4+-potentials with or without ethacrynic acid. Gluconate depolarized the K+-potential with ethacrynic acid and the NH4+-potential with or without ethacrynic acid. These findings suggest that NH4+ forms a diffusion potential in nerve endings, and inhibits the anion-mediated hyperpolarization through mechanisms other than anion channels.

Ammonia↗

PubMed1987

Histochemical demonstration of Cl(-)-ATPase in rat spinal motoneurons.

Using an enzyme-histochemical technique, rat spinal cords were stained for Cl(-)-ATPase, Na+,K+-ATPase and anion-insensitive Mg2+-ATPase. Cl(-)-ATPase activity was demonstrated in plasma membranes of spinal motoneurons, Na+,K+-ATPase activity and anion-insensitive Mg2+-ATPase activity were detected in neuronal plasma membranes and blood vessels, respectively.

Animals↗

PubMed1987

Inhibition of neuronal Cl-stimulated Mg-ATPase by alpha-human atrial natriuretic polypeptide.

Effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on neuronal membrane-bound adenosine triphosphatases (ATPases) (Na, K-ATPase, Cl-stimulated Mg-ATPase and anion-insensitive Mg-ATPase) were examined using rat brain microsomes. This peptide inhibited Cl-stimulated Mg-ATPase in a dose-dependent manner. The inhibition was non-competitive with respect to ATP, and was not affected by Cl-, the most potent stimulator of this enzyme. The activities of Na,K-ATPase and anion-insensitive Mg-ATPase were not changed by alpha-hANP at all.

Animals↗

PubMed1987

Effects of extracellular anions on cell growth of Chinese hamster V-79 cells.

The effects of extracellular anions (10-150 mM, added as Na salts to normal growth medium) on the growth of Chinese hamster V-79 cells were examined. Additions of NaCl and NaNO3 at concentrations greater than 60 mM reduced the growth rate dose-dependently. Several other anions also inhibited cell growth in the decreasing order of potency, SCN- greater than NO2- greater than NO3- greater than Br- greater than Cl- greater than gluconate- glutamate- greater than Mes-. When the added anions were removed, the growth rate was restored to the control rate. Cell survival was markedly reduced by the addition of SCN-, but was less affected by other anions (Cl-,NO3- and NO2-) of comparable potency. The respective syntheses of cellular DNA and protein, as estimated from the incorporation of [3H]-thymidine and [14C]leucine, also decreased with the increase in the concentration (60-120 mM) of anions added, the order of potency being SCN- greater than NO2- greater than NO3- greater than Cl-. After anion-treatment, the cellular Na+ concentration increased and the cellular Cl- concentration decreased in the order of SCN- greater than NO2- greater than NO3-, Cl-, but, the cellular K+ concentration did not change significantly. These data suggest that changes in extracellular anions affect cell growth and survival, probably through changes in the intracellular Na+ or Cl- concentration and in the rates of protein and/or DNA synthesis.

Animals↗

PubMed1987

Solubilization and separation of ethacrynic acid (EA) highly sensitive and EA less sensitive Mg2+-ATPases in the rat brain.

Rat brain microsomal Mg2+-ATPases with two distinct activities: ethacrynic acid (EA) highly sensitive and EA less sensitive Mg2+-ATPase activities were solubilized by the combined treatment with 10 mM 3-(3-chlolamidopropyl)-dimethylammonio-1-propane-sulfate (CHAPS) and 30 mM octyl-beta-D-glucoside. The solubilized enzymes had properties similar to those of the membrane-bound enzyme in microsomes with respect to the sensitivity to EA and Cl-, although the optimal pH and the affinity to ATP were slightly altered after the solubilization. Fast protein liquid chromatography of the solubilized enzymes on an anion-exchanger (Mono Q) column with a linear NaCl gradient (0-1.0 M) yielded separate peaks for EA highly sensitive and EA less sensitive Mg2+-ATPase activities at 0.1 and 0.35 M NaCl, respectively. Polyacrylamide gradient gel electrophoresis of the samples from the peak-fractions of EA highly sensitive and EA less sensitive Mg2+-ATPase activities yielded prominent bands at 600 and 70 kDa, respectively. These results indicate that EA highly sensitive Mg2+-ATPase is solubilized and separated from EA less sensitive Mg2+-ATPase as a large enzyme molecule with anion-sensitive sites.

Animals↗

PubMed1987

Sensitization to heat by amiloride analogues in Chinese hamster cells.

Effects of five amiloride analogues on thermal cell killing were examined using Chinese hamster V-79 cells. When cells were exposed to 42 degrees C hyperthermia in the presence of 0.2 mM amiloride or its analogue, cell survival decreased with increasing exposure time, as compared with that for exposure to 42 degrees C alone. The degree of the thermosensitizing effect varied among the test compounds, and three analogues were found to be more potent than amiloride. The results suggest that some of the amiloride analogues may be useful as hyperthermic sensitizers in the clinical treatment of cancer.

Amiloride↗

PubMed1986

[Properties of ATP-dependent H+-transport in rat brain synaptosomes].

Properties of the ATP-dependent H+-transport system in rat brain synaptosomes were examined using the acridine orange fluorescence quenching method. ATP-dependent H+-accumulation assessed by the quenching of acridine orange fluorescence was observed with the synaptosomes treated with hypotonic solution (hypotonic shock-synaptosomes), but not with the intact synaptosomes. With hypotonic shock-synaptosomes, H+-transport was activated in the presence of Cl- or Br-. However, this transport activity was markedly reduced in the presence of Mes-, NO3-, I- or SCN-. On the other hand, H+-transport activity was less effective with cations other than K+ in the following decreasing order of potency: K+ greater than Cs+ greater than Na+ greater than Li+. The H+-transport activity was inhibited by 0.3 mM ethacrynic acid, 10 microM 4-acetamide-4'-isothiocyanostilbene-2,2'-disulfonic acid or 1 mM 4-aminopyridine to 39.2%, 36.3%, or 33.1% of the control, respectively, but was not inhibited by 1 mM ouabain, 500 microM vanadate, 10 microM picrotoxin and 100 microM gamma-aminobutyric acid. These results suggest that the ATP binding site of the synaptosomal ATP-dependent H+-transport system exists on the internal surface of synaptosomal plasma membranes and that the H+-transport system is stimulated by the presence of Cl- or Br- and by K+ movement through the K+ channel.

Adenosine Triphosphate↗