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F Hata

Publications and source records attributed to F Hata.

At least 73 records · Page 4Linked to original sources
PubMed1997

Muscarinic autoinhibition and modulatory role of protein kinase C in acetylcholine release from the myenteric plexus of guinea pig ileum.

The modulatory role of protein kinase C on phospholipase A2, activation of which had been suggested to result in acetylcholine release from cholinergic neurons, was studied in longitudinal muscle preparations with the myenteric plexus of guinea pig ileum. The relationship of muscarinic autoinhibition to the modulation was also examined. Phorbol-12,13-dibutyrate (PDBu), an activator of protein kinase C, dose-dependently increased spontaneous and electrical field stimulation-induced acetylcholine releases from the preparation. The inhibitors of protein kinase C, staurosporine and calphostin C, inhibited the stimulatory effects of PDBu, but neither inhibitor affected spontaneous or electrical field stimulation-induced acetylcholine release in the absence of PDBu. On the other hand, atropine significantly increased electrical field stimulation-induced release by blocking a muscarinic autoinhibitory mechanism. Under the auto-inhibition blocked condition, U73122, an inhibitor of phospholipase C, and staurosporine significantly inhibited the effect of atropine on electrical field stimulation-induced release. An inhibitor of phospholipase A2, mepacrine, inhibited PDBu-induced acetylcholine release and also inhibited the effect of atropine on electrical field stimulation-induced release. An activator of phospholipase A2, melittin, and a product of the phospholipase, arachidonic acid, increased the spontaneous and electrical field stimulation-induced releases. These results suggest that the phospholipase C-protein kinase C system modulates acetylcholine release from cholinergic neurons by activating phospholipase A2 in the myenteric plexus of guinea pig ileum, and the activation of muscarinic autoreceptor may negatively modulate acetylcholine release at a point upstream of the system.

Acetylcholine↗
PubMed1997

Characterization of antimuscarinic effect of cimetropium bromide in guinea pig ileum.

Pharmacological characteristics of cimetropium bromide (cimetropium), a muscarinic receptor antagonist, were studied in longitudinal muscle preparations with myenteric plexus of guinea-pig ileum. Cimetropium was shown to have more potent antimuscarinic effect than butylscopolamine in inhibition of contraction of the preparations. Interestingly, when the inhibitory effects of cimetropium were compared in respect of relative potency to atropine between its effects on electrical field stimulation or nicotine-, and exogenous ACh-induced contraction, it has a more potent effect on the former contraction than that on the latter one. In the superfusion experiments of the preparation which had been preloaded with labelled choline, cimetropium decreased the labelled ACh release induced by electrical field stimulation under the muscarinic autoinhibition blocked-condition. From these findings, two pharmacologically characteristic effects of cimetropium in addition to post-synaptic muscarinic receptor antagonism were suggested: one is a weak effect on muscarinic autoreceptors in comparison to atropine and the other is an inhibitory effect on the ACh release.

Acetylcholine↗
PubMed1996

Ca(2+)-independent fusion of synaptic vesicles with phospholipase A2-treated presynaptic membranes in vitro.

To clarify the mechanism of exocytosis in neurotransmitter release, the fusion of synaptic vesicles with presynaptic membranes prepared from rat brain synaptosomes and concomitant acetylcholine (ACh) release induced by fusion of them were studied in vitro. Fusion of the synaptic vesicles with presynaptic membranes was measured by a fluorescence-dequenching assay with octadecyl rhodamine B. Synaptic vesicles fused with presynaptic membranes which had been pretreated with porcine phospholipase A2 (PLA2) in the presence of 20 microM Ca2+ and released ACh, whereas synaptic vesicles did not interact with non-pretreated membranes. The fusion followed by ACh release depended (i) on the activity of PLA2 during the membrane pretreatment, (ii) on the amount of pretreated membrane and (iii) on the duration of the pretreatment. The presence of Ca2+ ions during the pretreatment was essential for inducing a fusogenic activity of the membranes, but Ca2+ ions were not required for the fusion itself because the fusion experiment was carried out in the presence of 5mM EGTA without added Ca2+. The presence of quinacrine, an antagonist of PLA2, during the membrane pretreatment inhibited their fusogenic activity, suggesting the importance of activation of PLA2. Presence of albumin during the pretreatment, which is an adsorbent of free fatty acids, also inhibited the fusogenic activity. Arachidonic acid, when added during the pretreatment, potentiated the fusogenic activity of the membrane. These findings suggest that the conformational change in the presynaptic membrane phospholipids induced by PLA2 and the presence of arachidonic acid produced by PLA2 are important in the process of fusion of synaptic vesicles with the presynaptic membranes of rat brain, and that the fusion process itself is independent of Ca2+.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1996

VIP- and PACAP-mediated nonadrenergic, noncholinergic inhibition in longitudinal muscle of rat distal colon: involvement of activation of charybdotoxin- and apamin-sensitive K+ channels.

1. The mediators of nonadrenergic, noncholinergic (NANC) inhibitory responses in longitudinal muscle of rat distal colon were studied. 2. An antagonist of pituitary adenylate cyclase activating peptide (PACAP) receptors, PACAP6-38, concentration-dependently inhibited the rapid relaxation of the longitudinal muscle induced by electrical field stimulation (EFS), resulting in a maximal inhibition of 47% at 3 microM. 3. PACAP6-38 inhibited the relaxation by 75% in the presence of the vasoactive intestinal peptide (VIP) receptor antagonist, VIP10-28 at 3 microM, which inhibited the relaxation by 44%. 4. An antagonist of large conductance Ca(2+)-activated K+ channels, charybdotoxin, concentration-dependently inhibited the rapid relaxation of the longitudinal muscle, resulting in a maximal inhibition of 58% at 100 nM. 5. An antagonist of small conductance Ca(2+)-activated K+ channels, apamin, concentration-dependently inhibited the relaxation (58% at 1 microM). 6. Treatment with both K+ channel antagonists resulted in 84% inhibition of the EFS-induced relaxation, which is comparable to the extent of inhibition induced by PACAP6-38 plus VIP10-28. 7. The inhibitory effect of VIP10-28 and of apamin, but not of charybdotoxin was additive: the same applied to PACAP6-38 and charybdotoxin, but not apamin. 8. Exogenously added VIP (100 nM 1 microM) induced a slow gradual relaxation of the longitudinal muscle. Charybdotoxin, but not apamin significantly inhibited the VIP-induced relaxation VIP10-28, but not PACAP6-38 selectively inhibited the VIP-induced relaxation. 9. Exogenously added PACAP (10-100 nM) also induced slow relaxation. Apamin and to a lesser extent, charybdotoxin, inhibited the PACAP-induced relaxation. PACAP6-38, but not VIP10-28 selectively inhibited the PACAP-induced relaxation. 10. Apamin at 100 nM inhibited inhibitory junction potentials (i.j.ps) induced by a single pulse of EFS Apamin also inhibited a rapid phase, but not a delayed phase of i.j.ps induced by two pulses at 10 Hz. VIP10-28 did not inhibit i.j.ps induced by a single pulse, but significantly inhibited the delayed phase at two pulses. A combination of apamin and VIP10-28 abolished the i.j.ps induced by two pulses. 11. Both VIP and PACAP induced slow hyperpolarization of the cell membrane of the longitudinal muscle. Apamin inhibited the PACAP-, but not VIP-induced hyperpolarization. 12. From these findings it is suggested that VIP and PACAP are involved in NANC inhibitory responses of longitudinal muscle of the rat distal colon via activation of charybdotoxin- and apamin-sensitive K+ channels, respectively.

Animals↗
PubMed1996

Nitric oxide-mediated relaxation without concomitant changes in cyclic GMP content of rat proximal colon.

1. We studied the relation of nitric oxide-mediated relaxation of longitudinal muscle to changes in cyclic GMP content of the tissue in the proximal colon of rats. 2. Dimethylphenylpiperazinium (DMPP) and electrical field stimulation (EFS) induced nitric oxide-mediated relaxation of the segments with a concomitant increase in cyclic GMP content. 3. LY 83583 and methylene blue, soluble guanylyl cyclase inhibitors, significantly inhibited the stimulatory effects of DMPP and EFS on the cyclic GMP content, but did not affect the relaxant responses of the segments to DMPP and EFS. 4. Rp-8 bromo cyclic GMPS, an inhibitor of cyclic GMP-dependent protein kinase had no effect on DMPP- and EFS-induced relaxation. 5. These data strongly suggested that nitric oxide-mediated relaxation of the rat proximal colon is not associated with change in cyclic GMP content of the tissue.

Aminoquinolines↗
PubMed1996

Cooperation of ATP and norepinephrine in inducing contraction in guinea pig vas deferens is not associated with change in intracellular Ca2+ level.

Contractile responses and fura-2 fluorescence signals were simultaneously recorded in fura-2 loaded longitudinal muscle strips of guinea pig vas deferens to examine the relationship between cooperation of ATP and norepinephrine (NE) in the contractile response and intracellular Ca2+ level. ATP or NE induced a rapid or delayed contraction, respectively, with concomitant changes in fura-2 signal. Addition of both agonists potentiated the rapid, but not delayed contraction, while there was no potentiation in the fura-2 signal. In another series of experiments, NE (> or = 10 microM) contracted the muscle without further concomitant increase in Ca2+ level, indicating "Ca2+ sensitization" of the contractile apparatus. These findings suggest that cooperation of ATP and NE in inducing a rapid contraction of guinea pig vas deferens is mainly due to the "Ca2+ sensitization" effect of NE.

Adenosine Triphosphate↗
PubMed1995

Ca(2+)-independent fusion of secretory granules with phospholipase A2-treated plasma membranes in vitro.

The fusion of secretory granules with plasma membranes prepared from rat parotid gland was studied in vitro to clarify the mechanism of exocytosis. Fusion of the granules with plasma membranes was measured by a fluorescence-dequenching assay with octadecyl rhodamine B, and release of amylase was also measured to confirm the fusion as a final step of the secretory process. Plasma membranes that had been pretreated with porcine phospholipase A2 (PLA2) in the presence of 20 microM Ca2+ fused with the granules within 30 s, and induced amylase release by reacting with the membranes of granules, whereas without this pretreatment they had no significant effect. The fusion process accompanied by amylase release was induced in the presence of 10 mM EGTA, and therefore was apparently Ca(2+)-independent. On the other hand, the presence of EGTA or 100 microM quinacrine, an inhibitor of PLA2, during treatment of plasma membranes with PLA2 inhibited their fusogenic activity, suggesting the importance of activation of PLA2. Arachidonic acid and linoleic acid were released from the plasma membranes during the PLA2 treatment. The presence of albumin, an adsorbent of fatty acids, during the treatment also inhibited the activity. Pretreatment of the membranes with arachidonic acid or linoleic acid did not have any effect, but the presence of exogenously added arachidonic acid during PLA2 treatment enhanced the membrane-fusion-inducing effect of PLA2. Pretreatment of the membranes with lysophosphatidylcholine induced fusogenic activity. These findings suggest that the conformational change in the plasma-membrane phospholipids induced by PLA2 and the presence of arachidonic acid or linoleic acid produced by PLA2 are important in the process of fusion of secretory granules with the plasma membranes of rat parotid acinar cells and that the fusion process itself is independent of Ca2+.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1995

Effects of H-89, an inhibitor of protein kinase A, on the acetylcholine release from myenteric plexus of guinea pig ileum.

In order to clarify the involvement of cyclic AMP-dependent protein kinase (protein kinase A) in acetylcholine (ACh) release from myenteric plexus of guinea pig ileum, the effect of H-89, a specific inhibitor of protein kinase A, on the ACh release was investigated. H-89 (0.1-10 microM) inhibited the spontaneous and nicotine-induced release of ACh in a concentration dependent manner. It at 1 microM decreased both kinds of release of ACh to almost half of the control, but it did not affect the ACh release evoked by electrical field stimulation and by 5-hydroxytryptamine. H-89 had no significant effect on the indomethacin (IND), an inhibitor of PG synthesis, -insensitive component of the spontaneous and nicotine-induced release of, ACh. OP-41483, an analog of PGI2 and forskolin, an activator nicotine-induced release of, ACh. OP-41483, an analog of PGI2 and forskolin, an activator of adenylate cyclase, reversed the inhibitory effect of IND on the ACh release. H-89 at 1 microM completely inhibited the reverse effects of OP-41483 and forskolin. These results suggest that activation of protein kinase A is essential for modulation of the nicotine-induced and spontaneous ACh release from myenteric plexus of guinea pig ileum and the activity of protein kinase A is regulated by endogenous PGs via intracellular cyclic AMP level.

Acetylcholine↗
PubMed1995

Necessity of newly synthesized ATP by creatine kinase for contraction of permeabilized longitudinal muscle preparations of rat proximal colon.

Necessity of newly synthesized ATP by creatine kinase for synthesis of ATP as an energy source for smooth muscle contraction was studied in permeabilized longitudinal muscle preparations of rat proximal colon. In alpha-toxin-permeabilized preparations, Ca++ induced "phasic type" contraction in a normal bath solution containing 4 mM ATP and 5 mM phosphocreatine. Omission of phosphocreatine from the solution resulted in significant decrease in phasic contraction, and omission of ATP resulted in loss of the response to Ca++. When ADP, but not adenosine-5-O-(2-thiodiphosphate), with phosphocreatine was added as a substitute for ATP, Ca++ induced the same type of contraction as with ATP. The maximum tensions of the phasic and tonic phases of the contraction with ADP were approximately 60% of, and almost the same, respectively as those with ATP. A selective inhibitor of creatine kinase, 2,4-dinitrofluorobenzene, inhibited the phasic contraction induced by Ca++. After irreversible inhibition of endogenous creatine kinase by DNFB in beta-escin-permeabilized preparations, treatment of the preparations with exogenous creatine kinase restored Ca(++)-induced contraction. These findings suggest that ATP synthesized from ADP and phosphocreatine by creatine kinase was necessary for phasic contraction of permeabilized smooth muscle and that exogenous ATP was mainly used after its hydrolysis to ADP.

Adenosine Diphosphate↗
PubMed1995

Involvement of heterotrimeric GTP-binding protein and rho protein, but not protein kinase C, in agonist-induced Ca2+ sensitization of skinned muscle of guinea pig vas deferens.

We studied the involvement of protein kinase C (PKC) and a small GTP-binding protein (G-protein), rho, in receptor-mediated Ca2+ sensitization of the contractile apparatus of smooth muscle of guinea pig vas deferens. In beta-escin-permeabilized smooth muscle strips, norepinephrine (NE) in the presence of GTP caused further contraction of the preparations at a constant Ca2+ level (Ca2+ sensitization). Prazosin and GDP beta S, a nonhydrolyzable GDP analogue, inhibited NE-induced Ca2+ sensitization, indicating an alpha-1 adrenoceptor/G-protein mediated response. GTP alone (> 10 microM) and GTP gamma S, a non-hydrolyzable GTP analogue, also induced Ca2+ sensitization. Pretreatment of preparations with C3 exoenzyme of Clostridium botulinum, which is known to ADP-ribosylate rho family proteins, with NAD resulted in complete inhibition of NE- and GTP (GTP gamma S)-induced Ca2+ sensitization. AIF4-, which activates heterotrimeric G-, but not small G-protein also induced Ca2+ sensitization. Interestingly, AIF4(-)-induced Ca2+ sensitization was inhibited by not only GDP beta S but also C3-treatment, suggesting that activation of heterotrimeric GTP-binding protein precedes activation of rho protein. On the other hand, phorbol 12,13-dibutyrate, like NE, also induced Ca2+ sensitization. The sensitization was inhibited by PKC(19-31), a PKC inhibitor peptide. However, PKC(19-31) did not have any effect on NE- or AIF4(-)-induced Ca2+ sensitization.(ABSTRACT TRUNCATED AT 250 WORDS)

ADP Ribose Transferases↗
PubMed1994

Changes in neuronal contribution to contractile responses of vas deferens of young and adult guinea pigs.

The response characteristics of vas deferens to electrical hypogastric nerve stimulation at various frequencies was studied in guinea pigs of 2 to 15 weeks old. In 2-week-old guinea pigs the stimulation induced monophasic contraction, some of which remained after blocking alpha 1-adrenoceptor and desensitizing P2-purinoceptors with prazosin and alpha, beta-methylene ATP, respectively. In guinea pigs of 10 to 15 weeks old stimulation induced biphasic contraction, which was almost completely inhibited by both blockers. These results suggest that some unknown component other than ATP and norepinephrine is involved in the transmission at 2 weeks, and that its relative significance changes during development.

Adenosine Triphosphate↗
PubMed1994

Differences in relaxant effects of cyclic GMP on skinned muscle preparations from the proximal and distal colon of rats.

The relationship between the intracellular cyclic GMP content and relaxation of smooth muscle was studied in preparations from the proximal and distal colon of rats. Nitric oxide increased the cyclic GMP content of longitudinal muscle of both preparations to approximately the same extents. However, although nitric oxide at 0.03-10 microM induced concentration-dependent relaxation of the proximal segments, it did not induce any significant relaxation of the distal segments. The longitudinal muscle preparations were permeabilized by treatment with alpha-toxin to examine the relaxant effects of cyclic GMP on the contractile elements. Ca2+ induced contraction of the permeabilized muscle, the contraction consisting of a transient and subsequent tonic phases. Cyclic GMP (3-100 microM) reversed the tonic contractions induced by various Ca2+ concentrations (1-30 microM). The magnitude of the relaxant effect of cyclic GMP was significantly more in the proximal region than in the distal region. But in contrast to nitric oxide, cyclic GMP induced slight, but clear relaxation of the distal colon. The inhibitory effects of cyclic GMP on phasic contraction, like those on tonic contraction, were high in the proximal region and low in the distal region. These results suggest that the difference in the relaxant effects of nitric oxide in the proximal and distal longitudinal muscles is not due to a difference in extents of cyclic GMP generation, but mainly to a difference in the sensitivities of the contractile elements in the two regions to cyclic GMP.

Animals↗
PubMed1994

Tissue transmigration of CZON (Cosmosin) to middle ear mucosa, maxillary sinus mucosa, and palatine tonsils.

The concentration of CZON was determined by HPLC in surgical patients with chronic otitis media, sinusitis, and tonsillitis. One gram of CZON was injected intravenously prior to surgery. The time course of the mean tissue CZON level was as follows: In the middle ear mucosa, 3.7 micrograms/g at 15 min, 7.2 micrograms/g at 30 min, and 2.9 micrograms/g at 1 hr (the half life: 21.3 min). In the maxillary sinus mucosa, 10.5 micrograms/g at 15 min, 11.8 micrograms/g at 30 min, and 2.8 micrograms/g at 1 hr (the half life: 17.5 min). In the tonsils, 14.9 micrograms/g at 15 min, 9.3 micrograms/g at 30 min, and 2.0 micrograms/g at 1 hr (the half life: 13.2 min). The concentration was high in the maxillary sinus mucosa and the tonsils, but was low in the middle ear mucosa. In the formers the transfer ratio reached its peak 15 to 30 min after administration, but in the latter the peak was reached 30 to 60 min after administration. The order of the transfer ratio at each region was above 25%. The tissue concentration exceeded the MIC80s of frequent isolates from these infections. CZON is considered to be a highly useful drug in the treatment of these infections.

Adolescent↗
PubMed1994

Nitric oxide-mediated inhibitory response of rat proximal colon: independence from changes in membrane potential.

1. We studied the relation of nitric oxide-mediated relaxation of smooth muscle to changes in membrane potential of cells in the proximal colon of rats. 2. The resting membrane potential and electrical field stimulation (EFS)-induced junction potentials were recorded from the circular and longitudinal muscle cells. 3. Localized distension with a small balloon caused relaxation of the circular muscle on the anal side of the distended region (descending relaxation). Relaxation of the longitudinal muscle was also induced by EFS. 4. Inhibitory junction potentials (i.j.ps) were recorded from all circular muscle cells tested, but rarely from the longitudinal muscle cells. 5. The i.j.ps were recorded only in the presence of atropine but relaxations of both muscles were induced even in the absence of atropine. 6. Apamin (100 nM) completely abolished the i.j.ps recorded in both circular and longitudinal muscle cells, but had no significant effect on the relaxations of either. 7. In contrast to apamin, Ng nitro-L-arginine (10 microM) inhibited the relaxations of both muscles, but did not affect the i.j.ps. 8. Exogenously added nitric oxide (0.1-10 microM) induced relaxations of both muscles concentration-dependently, but did not affect the membrane potentials at these concentrations. 9. These data strongly suggest that nitric oxide-mediated relaxation of rat proximal colon is not associated with the i.j.ps of the cell membrane.

Animals↗
PubMed1993

Neuronal pathway involved in nitric oxide-mediated descending relaxation in rat ileum.

The neuronal pathway that initiates nitric oxide-mediated descending relaxation in rat ileum was studied. The descending relaxation, which was suggested to be mediated by nitric oxide from our previous study, was selectively inhibited by 5-HT3 receptor antagonists. It was also inhibited by a nicotinic acetylcholine receptor antagonist. Exogenous 5-hydroxytryptamine (5-HT) and a selective 5-HT3 receptor agonist induced dose-dependent relaxation of ileal circular muscle. 5-HT-induced relaxation was selectively inhibited by 5-HT3 receptor antagonists. Nicotine also induced relaxation of the circular muscle, and its effect was inhibited by 5-HT3 receptor antagonists. 5-HT and nicotine increased the cyclic GMP content of the ileal tissue. Nitro-L-arginine inhibited the increases induced by both compounds in the cyclic GMP content, and a 5-HT3 receptor antagonist also inhibited that induced by nicotine. These results indicate that activation of a cholinergic neuron-5-HT neuron pathway initiates nitric oxide-mediated descending relaxation in rat ileum.

Animals↗