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S Ichida

Publications and source records attributed to S Ichida.

At least 55 records · Page 3Linked to original sources
PubMed1987

General characteristics of the superprecipitation reaction of rat crude uterine myosin B: effects of L-methionine and/or transmethylation blockers on the reaction.

The characteristics of superprecipitation of uterine myosin B from 17 beta-estradiol-3-benzoate-treated rats and the effects of L-methionine and/or 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL) on the reaction were investigated. The slope and plateau phases of the superprecipitation were dependent on ATP, calcium and magnesium. The calmodulin antagonists, trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide, inhibited the slope and plateau phases, but not the basal superprecipitation. SDS-polyacrylamide gel electrophoresis of the precipitate obtained in complete medium showed the presence of actin and myosin. Addition of 3 mM L-methionine had little affect on either the slope or plateau phases of the basal- or calcium-dependent superprecipitation, while 500 microM 3-DAA plus 1 mM HCTL caused only 9 to 20% decrease in the calcium-dependent superprecipitation in the presence of 0.1 mM or 1 mM ATP. These findings suggest that the calcium-dependent superprecipitation of rat uterine myosin B reflected the contractile response of uterine muscle, and that L-methionine and/or 3-DAA plus HCTL did not affect the calcium-dependent superprecipitation of uterine myosin B.

Animals↗
PubMed1986

L-methionine enhances the contractile responses of rat uterine smooth muscle to acetylcholine and high KCl.

The contractile responses of isolated uterine smooth muscle from estradiol-treated ovariectomized rats to acetylcholine and high KCl in Ca-depleted modified Locke-Ringer (without CaCl2 and with 0.1 mM EGTA) solution on addition of CaCl2 (final concentration, 5 mM) are used as an indicator of Ca influx through the Ca channel. L-Methionine significantly enhanced these responses in the absence and presence of 3-deazaadenosine plus homocysteine thiolactone, blockers of methylation. These findings suggest that methylations of some components in isolated uterine smooth muscle seem to be important in stimulation-contraction coupling in the muscle.

Acetylcholine↗
PubMed1986

Total acetylcholine content, and activities of choline acetyltransferase and acetylcholinesterase in brain and duodenum of SART-stressed (repeated cold-stressed) rat.

The cholinergic activities in SART (specific alternation of rhythm in temperature)-stressed (repeated cold-stressed) rats, which are diseased rats with vagotonic-type dysautonomia, were examined with the following results. A decreased content of total acetylcholine (T-ACh) and increased activities of choline acetyltransferase (CAT) and acetylcholinesterase (ACh) in the basal ganglia and an increase in the T-ACh content and decrease in the AChE activity in the duodenum of SART-stressed rats reached the respective plateaus on day 5 of stress, which were maintained thereafter. CAT activity, however, in the hypothalamus was activated most on day 2. These changes in SART-stressed rats were different from those in simple cold-stressed rats. Subdiaphragmatic vagotomy inhibited the appearance of the changes in the duodenum, but not those in the hypothalamus of SART-stressed rats. The sedative analgesic Neurotropin prevented all the changes in SART-stressed rats described above. These results suggest that cholinergic neurons may be activated in both the hypothalamus and basal ganglia of the brain of SART-stressed rats, and the characteristic peripheral changes of the cholinergic system in the duodenum of SART-stressed rats may be under the control of the parasympathetic center.

Acetylcholine↗
PubMed1986

[Postural effects in the jugular phlebogram in patients with complete absence of the left pericardium].

To elucidate the function of the pericardium, alterations in jugular phlebograms, intracardiac pressures and cardiac volumes induced by postural changes were examined in seven patients with complete absence of the left pericardium. Ten patients with ischemic heart disease were studied as controls. Jugular phlebograms in patients with complete absence of the left pericardium showed decreased depths of the x descent and the tall v waves followed by the deep y descents (M-shaped pattern) in the supine position. These jugular abnormalities were exaggerated in the left lateral decubitus position. By contrast, the jugular phlebograms tended to return to normal, but remained abnormal in the right lateral decubitus position. Right atrial pressure curves showed similar postural effects. However, the jugular phlebograms and right atrial pressure curves in patients with ischemic heart disease were not altered by postural changes. The characteristic alterations of the jugular phlebograms are useful indicators for diagnosing complete absence of the left pericardium. The lack of a prompt decrease in pericardial pressure during ventricular ejection due to the absence of the pericardium is one of the causes of a decreased depth of the x descent in pericardial defect. However, this cannot explain the postural alteration of the jugular phlebogram. Another possible mechanism is the decreased excursion of the tricuspid ring during systole. As indicated in our previous report, there is anterior movement of the cardiac apex during systole in cases of pericardial defect, which is exaggerated in the left lateral decubitus position and decreased in the right lateral decubitus position due to the lack of normal pericardial support. This anterior swinging motion may inhibit the descent of the tricuspid ring toward the apex, resulting in a decreased depth of the x descent of the jugular phlebogram and the right atrial pressure curve and their postural alterations. The right ventricular volume as calculated from cardiac computerized tomography and the right ventricular end-diastolic pressure were not altered significantly by postural changes in the control cases. These indices increased to a greater extent in the left lateral decubitus position than in other postures in cases with pericardial defects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Estradiol-induced increase of specific [3H]ketanserin binding sites on rat uterine membranes.

[3H]Ketanserin, a specific serotonin (5-HT) antagonist, was used to investigate whether 5-HT receptors increased in the uterine membranes of ovariectomized rats on administration of 17 beta-estradiol-3-benzoate (estradiol) and also to investigate the characteristics of specific [3H]ketanserin binding to the uterine membranes from estradiol-treated ovariectomized rat. Administration of estradiol significantly increased the amount of [3H]ketanserin specifically bound at equilibrium but did not change the apparent affinity of specific [3H]ketanserin binding. The specific [3H]ketanserin binding to estradiol-treated ovariectomized preparations was rapid and reversible. The Scatchard plots of the saturation curves of specific [3H]ketanserin binding to untreated and estradiol-treated ovariectomized preparations were convex. The apparent Ki values of various serotonergic agents deduced from displacements by these compounds of specific [3H]ketanserin binding to estradiol-treated ovariectomized preparations were two to four orders of magnitude smaller than those of adrenergic, dopaminergic and histaminergic agents. These results suggest that [3H]ketanserin binds mainly to 5-HT receptors in the uterine membranes of estradiol-treated ovariectomized rats.

Animals↗
PubMed1985

Clinical characteristics of coronary artery spasm: electrocardiographic, hemodynamic and arteriographic assessment.

We studied the clinical characteristics of 153 patients with angina pectoris associated with coronary artery spasm (CAS). The study was designed to investigate the relationship of CAS to ST segment deviation and to the site of fixed stenosis, and hemodynamic alteration during a spastic event. Analysis of coronary arteriograms and multilead electrocardiograms obtained simultaneously from 170 events of CAS by the use of radioluscent carbon-fiber electrodes resulted in 58 events with ST elevation which were related to total occlusion of major coronary arteries due to CAS; another 54 events with ST depression, in which the affected coronary arteries demonstrated severe but incomplete occlusion, or total occlusion but were visualized via collateral vessels; and remaining 58 events without ST deviation showing mild occlusion. The results indicate a close correlation between magnitude of CAS and ST segment deviation. CAS occurred at the site of pre-existing fixed stenosis including minor plaque defect in 133 patients and at apparently normal site in 20 patients. In the former group, only four patients had triple vessel disease, while 95 had nonsignificant fixed lesion. In the latter group, 10 patients had minor lesion distant from the site of CAS. Thus, CAS is closely related to fixed stenosis, which may have but a limited role as a cause of CAS. Hemodynamic measurements during spastic events were obtained from 49 patients including 41 events with spasm of the left anterior descending artery (LAD) and 21 events with spasm of the right coronary artery (RCA). The onset of an increase in left ventricular (LV) filling pressure and a reduction in LV dP/dt preceded ST segment deviation in all events. The first hemodynamic variable manifested in the spastic event was the reduction of LV contraction dP/dt in the majority of patients. The increase of LV filling pressure was greater in LAD spasm than RCA spasm (11 +/- 6 mmHg vs 7 +/- 4 mmHg, P less than 0.0125) and in events with ST elevation than with ST depression (11 +/- 5 mmHg vs 6 +/- 5 mmHg, p less than 0.001). Right ventricular functional impairment was mild in most patients during CAS. The study indicates that mechanical impairment precedes electrical impairment during CAS and that LAD spasm with ST elevation represents the most severe LV dysfunction.

Adult↗
PubMed1984

Absence of correlation between ACh-induced Ca influx and phosphatidic acid labeling in rat uterus.

Rat uterine smooth muscle was preincubated in Ca-depleted modified Locke-Ringer solution to investigate the correlation between the 32Pi incorporation into phosphatidic acid induced by acetylcholine and the contractile response to acetylcholine induced by the addition of CaCl2 (Ca influx). The results showed that in rat uterine smooth muscle under these conditions phosphatidic acid does not act as a Ca ionophore or as a trigger for opening the Ca channel.

Acetylcholine↗
PubMed1984

Purification and characterization of a fish lectin from the external mucus of ophidiidae, Genypterus blacodes.

A lectin was isolated from the external mucus of fish, Genypterus blacodes. This is the first lectin isolated from fish. The molecular weight of the lectin, determined by gel filtration, was approximately 32 000, whereas 8 000 was indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol. Amino acid analysis demonstrated that the lectin contained large amounts (near 30% of the residues) of lysine, but no tryptophan. The lectin agglutinated mouse, rabbit and human erythrocytes at a concentration of 15.6 micrograms/ml. An inhibition test revealed that the lectin was strongly inhibited by N-acetyl-glucosamine, mucin and orosomucoid. Binding studies performed with iodinated asialo-orosomucoid indicated that the lectin contained a high affinity binding site with a dissociation constant of 1.1 X 10(-8) M. The lectin required the presence of calcium ion for both its hemagglutination and binding activity.

Amino Acids↗
PubMed1984

Mitogenic activity and in vitro fertilization inhibitory activity of Genypterus blacodes lectin.

A lectin which we purified from the mucous of Ophidiidae Genypterus blacodes showed a potent mitogenic activity which was comparable to that of concanavalin A (con A). On the other hand, the lectin treated with 2-mercaptoethanol showed an anti-mitogenic activity against con A and lipopolysaccharide (LPS). Lymphocytes were separated into a T cell rich fraction and B cell rich fraction by soybean agglutinin. The mitogenic activity of G. blacodes lectin was examined using these cells. It was suggested that the mitogenic activity of G. blacodes lectin was based on the stimulation of T cells. The lectin was also subjected to both the sperm agglutination and the in vitro fertilization tests in mouse. It was demonstrated that: a) the lectin receptors were ubiquitous on sperm; b) in vitro fertilization of mouse ova was completely blocked by the binding of the lectin to the zona pellucida of the ova.

Animals↗
PubMed1984

Characteristics of ca influxes through voltage- and receptor-operated Ca channels in uterine smooth muscle.

The characteristics of Ca channels in isolated uterine smooth muscles from estradiol-treated ovariectomized rats were investigated. When the muscles were preincubated in Ca-depleted Ringer's solution for about 60 min and then immersed in Ca-depleted high K Ringer's solution or treated with acetylcholine (ACh) and serotonin (5-HT), no contractile response was observed. However, in both cases when CaCl2 was then added, a contractile response was induced. The contractile responses induced by KCl, ACh and 5-HT were inhibited dose-dependently by Ca antagonists and these inhibitions were counteracted competitively by an increase in the concentration of CaCl2. The characteristics of KCl-, ACh- and 5-HT-stimulated 45Ca uptake were investigated under the same conditions as the contractile responses. Results indicated that the contractile responses to high KCl, ACh and 5-HT induced by addition of CaCl2 in Ca-depleted Ringer's solution were dependent upon influx of Ca ions into uterine smooth muscle cells.

Acetylcholine↗
PubMed1984

Mechanisms of specific change by estradiol in sensitivity of rat uterus to serotonin.

The sensitivity (contractile response) to serotonin (5-HT) of the isolated rat uterus was increased either during estrus or by administration of estradiol to ovariectomized rats. These increases in sensitivity to 5-HT were specific, because the sensitivities to acetylcholine and oxytocin were not influenced in either case. Pargyline (10(-5) M), an inhibitor of monoamine oxidase, did not affect the contractile responses to 5-HT, acetylcholine and oxytocin of uterus from ovariectomized rats. The monoamine oxidase activities in 100,000 X g precipitates and supernatants of homogenates for uteri from ovariectomized rats were either increased or unchanged by administration of estradiol. The contractile response to 5-HT of the uterus of untreated ovariectomized rats was not affected by chlorimipramine at 10(-6) M, a concentration that inhibits 5-HT uptake. Administration of estradiol increased significantly the number of [3H]spiroperidol binding sites (5-HT receptors) from 0.56 +/- 0.04 to 1.23 +/- 0.11 pmol/mg of protein, but did not change the apparent affinity of 5-HT receptors. Administration of estradiol did not change the dissociation constant or number of binding sites for [3H]quinuclidinyl benzilate (muscarinic acetylcholine receptors) significantly. These results indicate that the specific increase in sensitivity to 5-HT on administration of estradiol is due to change in the number of 5-HT receptors, but not to change in 5-HT uptake or in metabolic degradation of 5-HT.

Animals↗
PubMed1983

Selective inhibition by ketanserin and spiroperidol of 5-HT-induced myometrial contraction.

The inhibitory effects of ketanserin and spiroperidol (a neuroleptic drug) on the contractile response of isolated rat uterus to serotonin (5-HT) were investigated. Ketanserin caused non-competitive inhibition of the contractile response to 5-HT and showed more selective inhibition than the other 5-HT antagonists tested. The inhibitory effect of spiroperidol was comparable with the effects of classical 5-HT antagonists. These results suggest that ketanserin and spiroperidol selectively inhibit the contractile response of isolated rat uterus to 5-HT.

Animals↗
PubMed1983

Increase of serotonin receptors in rat uterus induced by estradiol.

[3H]Spiroperidol was used to label uterine membrane-binding sites that have the characteristics expected of serotonergic receptors. The characteristics of specific [3H]spiroperidol binding to the uterine membrane of 17 beta-estradiol-3-benzoate-treated ovariectomized rats were studied. The specific [3H]spiroperidol binding was rapid and reversible, and the half-maximal saturation, taken as the apparent dissociation constant (KD) for [3H]spiroperidol, was 5.16 +/- 0.24 (n = 12) nM [3H]spiroperidol. Scatchard plots of saturation curves of the specific [3H]spiroperidol binding were convex and the Hill coefficient was 2.06 +/- 0.11 (n = 12). Cinanserin, mianserin, metergoline (which are serotonergic antagonists), and serotonin (5-HT) inhibited the [3H]spiroperidol binding with apparent Ki values of 21.2, 14.1, 14.1, and 176.5 microM, respectively. Concentrations of 1 mM sulpiride (a dopaminergic antagonist) and dopamine reduced [3H]spiroperidol binding only 26 and 23%, respectively. 1 mM GTP reduced the potency of 5-HT (10(-6) - 10(-3) M) to displace bound [3H]spiroperidol. The uterine membranes were treated with various enzymes and protein-modifying reagents, and binding studies on the treated uterine membranes showed that protein(s), phospholipids, and N-acetyl-neuraminic acid in uterine membranes were important as specific binding sites of [3H]spiroperidol. Measurement of the specific binding of [3H]spiroperidol to uterine membranes from untreated and estradiol-treated ovariectomized rats showed that estradiol significantly increased the number of specific binding sites of [3H]spiroperidol, but did not change the apparent affinity of specific [3H]spiroperidol binding. Estradiol also did not change the dissociation constant or the number of binding sites for [3H]3-quinuclidinyl benzilate, which binds to muscarinic acetylcholine receptors. These findings suggest that [3H]spiroperidol mainly binds to 5-HT receptors in the uterine membrane of estradiol-treated ovariectomized rats. The finding that administration of estradiol significantly increased the number of [3H]spiroperidol-binding sites is consistent with the specific increase in the contractile response to 5-HT observed in isolated uterus from ovariectomized rats treated with estradiol.

Animals↗
PubMed1982

Effects of neurotransmitter candidates on 45Ca uptake by cortical slices of rat brain: stimulatory effect of L-glutamic acid.

The effects of neurotransmitter candidates and the characteristics of the stimulatory effect of L-glutamic acid (L-Glu) on 45Ca uptake by rat brain slices were investigated. 45Ca uptake was significantly stimulated by acetylcholine, serotonin and especially L-Glu, but not by other neurotransmitter candidates. L-Glu caused dose-dependent stimulation of 45Ca uptake (L-Glu-stimulated 45Ca uptake), its effect being half-maximal at 1 microM. The related compounds D-glutamic acid, D,L-alpha-aminoadipic acid and N-methyl-D,L-glutamic acid (final conc. of 10 microM) also stimulated 45Ca uptake, but less than 10 microM L-Glu. D,L-alpha-Methylglutamic acid and L-glutamic acid diethylether (final conc. of 10 microM), which are specific inhibitors of L-Glu, inhibited L-Glu-stimulated 45Ca uptake. Mg,Ca-ATPase activity was hardly affected by a concentration of 10 microM L-Glu that caused maximal stimulation of 45Ca uptake. These findings suggest that L-Glu-stimulated 45Ca uptake by brain cortical slices is linked to L-Glu receptor.

Acetylcholine↗
PubMed1981

Potassium stimulated 45Ca uptake by cortical slices of rat brain: effects of cyclic nucleotide derivatives.

The effects of dibutyryl cyclic GMP (db-cGMP) and dibutyryl cyclic AMP (db-cAMP) on potassium-stimulated 45Ca uptake by cortical slices of rat brain were investigated. db-cGMP specifically inhibited the initial rate of potassium-stimulated 45Ca uptake in a dose-dependent manner. Our findings supported the suggestion that cyclic GMP may play a regulatory role in depolarization-elicited Ca2+ influx in nerve endings in situ.

Animals↗