PubMed Health⌕ Search

Biomedical subjects

S Ichida

Publications and source records attributed to S Ichida.

At least 19 recordsLinked to original sources
PubMed1992

Effects of GTP analogues and activation of endogenous protein kinases on photoaffinity labeling with [3H](+)PN200-110 of crude membranes from rat heart and brain.

The effects of GTP analogues and conditions in which various endogenous protein kinases were activated on photoaffinity labeling with [3H](+)PN200-110 (PN) of crude membranes from rat cardiac muscle and whole brain were investigated. Photoaffinity labeling with 20 nM [3H](+)PN of these crude membranes was decreased by 100 microM GTP-gamma-S, but not by 100 microM GTP or 100 microM GDP-beta-S. Similar results were obtained on the effects of GTP and its analogues on the specific binding of 20 nM [3H](+)PN to these crude membranes under the same conditions. Activation of endogenous protein kinases in these crude membranes did not influence the photoaffinity labeling with [3H](+)PN. These results suggested the binding sites, or DPH-sensitive, or L-type, calcium channels in curde membranes from rat cardiac muscle and whole brain are directly or indirectly modulated by endogenous GTP-binding protein, but not by various endogenous protein kinases in these crude membranes.

Affinity Labels↗
PubMed1991

Effects of calcium channel agonists (BAY K 8644, CGP28392 and YC-170) on 45Ca uptake by rat uterine segments.

The characteristics of the stimulating effects of the calcium channel agonists BAY K 8644, CGP28392 and YC-170 on 45Ca uptake by rat uterine segments were investigated. BAY K 8644, CGP28392 and YC-170 caused about 150, 100 and 150% increase, respectively in the 45Ca uptake induced by 20 mM KCl. The ED50 values of BAY K 8644, CGP28392 and YC-170 were 1.8 X 10(-9), 2.5 X 10(-8) and 9.8 X 10(-9) M, respectively. These agonists had little effect on the 45Ca uptake induced by 10(-6) M acetylcholine. They also did not affect the basal 45Ca uptake. Their enhancing effects were blocked by the Ca channel antagonist nitrendipine. We conclude that rat uterine segments have voltage-sensitive Ca channels that are stimulated by Ca channel agonists (BAY K 8644, CGP28392 and YC-170) under depolarizing conditions and that the characteristics of the stimulating effects of CGP28392 and YC-170 on 45Ca uptake by rat uterine segments are qualitatively the same as those of BAY K 8644.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

Enhancement by L-methionine on the contractile response of uterine segments to acetylcholine and high KCl is mainly due to enhancement of Ca uptake.

Acetylcholine (ACh)- and high KCl-stimulated 45Ca uptake into rat uterine segments was inhibited by 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL), and this inhibitory effect was attenuated by L-methionine (L-Met). Ca-depleted Ringer solution in which uterine muscle had been incubated with L-Met did not enhance the contractile response of another uterine segment to ACh and high KCl in the presence of 3-DAA plus HCTL. These findings together with previous results suggest that the enhancing effect of L-Met on the contractile responses to ACh and high KCl is mainly due to an increase in Ca2+ uptake into the uterine muscle.

Acetylcholine↗
PubMed1989

Characteristics of specific bindings of nitrendipine and PN200-110 to various crude membranes: induction of irreversible bindings by UV irradiation.

The characteristics of the specific bindings of [3H]nitrendipine (Nit) and [3H](+)PN200-110 (PN) to crude membranes from rat skeletal, cardiac, and uterine muscle and whole brain were investigated, with special interest in the effect of UV irradiation on these bindings. The specific bindings of [3H]Nit and [3H](+)PN to these crude membranes were saturable and reversible. The specific bindings of [3H]Nit to all these membranes except crude skeletal membranes was maximum in the presence of 0.15 M NaCl plus 1 mM CaCl2 and minimal in the absence of these ions, but the specific bindings of [3H](+)PN to these crude membranes was not affected significantly by these ions. A calcium agonist and antagonists inhibited the specific bindings of [3H]Nit and [3H](+)PN to these crude membranes, the order of their inhibitory effects on specific [3H]Nit bindings being roughly Nit greater than or equal to (+)PN greater than or equal to (-)PN much greater than Bay K 8644 (Bay) greater than verapamil (Ver) greater than diltiazem (Dil). In crude skeletal membranes only, PN caused significant stereospecific inhibition. The order of inhibitions of specific [3H](+)PN bindings to these crude membranes was generally (+)PN greater than Nit greater than or equal to (-)PN greater than Bay much greater than Ver greater than or equal to Dil. In all these crude membranes, UV irradiation completely prevented decrease in the amount of specific binding of [3H](+)PN binding on addition of excess unlabeled (+)PN. These findings suggested that [3H]Nit and [3H](+)PN bind to voltage-sensitive calcium channels in crude membranes from rat skeletal, cardiac, and uterine muscle and whole brain, and that UV irradiation changes the specific bindings of [3H]Nit and [3H](+)PN from reversible to irreversible bindings.

Animals↗
PubMed1989

Photoaffinity labeling with dihydropyridine derivatives of crude membranes from rat skeletal, cardiac, ileal, and uterine muscles and whole brain.

The characteristics of photoaffinity labeling with the calcium agonist [3H]Bay K 8644 (Bay) and the calcium antagonists [3H]nitrendipine (Nit) and (+)PN200-110 (PN) of crude membranes from rat skeletal, cardiac, ileal, and uterine muscles and whole brain were investigated. In all these crude membranes, [3H](+)PN (20 nM) was mainly photoincorporated into one protein band with a molecular weight of 30,000 - 41,000 Da. It was also incorporated into some other bands of all these crude membranes. The photoincorporation of [3H](+)PN into these crude membranes was inhibited by the presence of 20 microM unlabeled (+)PN. The photoincorporation of [3H](+)PN into these crude membranes depended on its dose and on the time of UV irradiation. No incorporation of [3H](+)PN was observed in the absence of UV irradiation. The incorporation was not affected by the presence of 1 mM CaCl2 and/or 0.15 M NaCl, but was significantly decreased by 20 microM (+)PN and slightly decreased by 20 microM (-)PN, 20 microM Bay, 1 mM diltiazem, or 1 mM verapamil. Namely, enantiomers of PN caused various extents of stereoselective inhibition of photoaffinity labeling by [3H](+)PN of specific protein bands in these crude membranes. [3H]Nit was photoincorporated into these crude membranes in the same way as [3H](+)PN, but [3H]Bay was not photoincorporated. However, 20 microM unlabeled Nit did not consistently inhibit photoaffinity labeling with [3H]Nit. These findings suggested that measurement of photoaffinity of crude membranes from rat skeletal, cardiac, and uterine muscles and whole brain with [3H](+)PN by UV irradiation is a useful method for investigating the characteristics of the voltage-dependent calcium channels that are affected by 1,4-dihydropyridine derivatives.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Studies on chemical modification of Tulipa gesneriana lectin.

Modification of lysine, tyrosine, histidine, aspartic acid and glutamic acid residues did not affect the agglutinating activity of the Tulipa gesneriana lectin (TGL). Modification of two arginine residues per subunit in the lectin with either 2,3-butanedione or phenylglyoxal led to an almost complete loss of activity. An inactive lectin modified with 2,3-butanedione recovered a full activity on dialysis against Tris-HCl buffer. The presence of 0.1 M (alpha-1----6) linked mannotriose, a potent inhibitor of the lectin, protected all the arginine residues from modification and the lectin was fully active. Circular dichroism spectroscopy showed that no significant conformational change of TGL occurred following arginine modification. A treatment of the lectin solution with N-bromosuccinimide or 2-hydroxy-5-nitrobenzyl bromide, chemical reagents for tryptophan modification, caused turbidity of the solution, accompanied with complete loss of activity. The fluorescence emission spectrum of the lectin showed a characteristic tryptophan emission with a maximum centered at 336 nm. Upon addition of manno-oligosaccharides a decrease of the fluorescence intensity was observed, indicating that the environment of tryptophan residues altered. These results suggest that arginine and tryptophan residues are importantly involved in the sugar binding of TGL.

Amino Acids↗
PubMed1988

Extra- and intracellular calcium in vanadate-induced contraction of vascular smooth muscle.

The effects of extracellular Ca and Ca antagonists on vanadate-induced contractions of vascular smooth muscles of aortae and mesenteric arteries from rabbits, guinea pigs, and Wistar-Kyoto (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) were studied. Vanadate-induced contractions of aortae were greatly diminished by extracellular Ca removal; the size of the remaining contraction was variable. Vanadate-induced contractions of mesenteric arteries, which were only observed in the presence of elevated K, were suppressed by the removal of Ca. Verapamil and nifedipine depressed vanadate-induced contractions of aortae from WKY and SHRSP, whereas they produced no or only slight inhibition of responses in guinea pig and rabbit aortae. Ca uptake into smooth muscle cell increased in the presence of vanadate, but the increase was much less than that induced by high K. In saponin-skinned smooth muscle, vanadate depressed the Ca-induced contraction. It is concluded that the vanadate-induced contraction utilizes both extracellular and intracellularly bound Ca, the relative contribution of which varies from preparation to preparation.

Animals↗
PubMed1988

Characteristics of acetylcholine-induced phosphorylase a activity in uterine segments as a substitute for contractile response to acetylcholine.

Studies were made on whether the ACh-induced phosphorylase a activity in isolated rat uterine muscle segments could be used as a substitute for the contractile response to ACh. This ACh-induced phosphorylase a activity was dependent upon the concentration of ACh and was inhibited by atropine, suggesting that it was linked to muscarinic ACh receptors. Both extracellular calcium and an increase of the intracellular calcium concentration were needed for its activation by ACh. Ca2+-antagonists such as Co2+, diltiazem, nitrendipine and verapamil inhibited the ACh-induced activity, suggesting that the activation by ACh required the influx of calcium ions into the uterine muscle through Ca2+-antagonist sensitive Ca2+ channels. The IC50 values of CoCl2, diltiazem, nitrendipine and verapamil on the ACh-induced phosphorylase a activity were 3.4 x 10(-3) M, 2.5 x 10(-4) M, 2.5 x 10(-5) M and 1.1 x 10(-4) M, respectively. These values were comparable with the IC50 values of these Ca2+-antagonists on the contractile response of isolated rat uterine muscle segments to 3 x 10(-4) M ACh. The inhibitory effects of Co2+, nitrendipine and verapamil, but not diltiazem, on ACh-induced phosphorylase a activity were attenuated by higher concentrations of CaCl2 (0.36 to 2 mM). These findings suggested that the ACh-induced phosphorylase a activity in isolated rat uterine muscle segments could be used as a substitute for the contractile response to ACh.

Acetylcholine↗
PubMed1988

Effects of synthetic omega-conotoxin on the contractile responses of segments of rat ileum, stomach fundus and uterus and guinea pig taenia coli.

The effect of synthetic omega-conotoxin (omega-CgTX) on the contractile responses of segments of rat ileum, stomach fundus and uterus and guinea pig taenia coli were investigated. Omega-CgTX (10(-9)-5 x 10(-6) M) did not inhibit the contractile responses of all smooth muscle segments to high KCl and/or ACh. However, unexpectedly, omega-CgTX (3 x 10(-7)-10(-5) M) alone caused dose-dependent contraction of segments of the stomach fundus and uterus. These contractile responses to omega-CgTX alone depended upon the presence and/or the influx of extracellular Ca2+; and they were inhibited by calcium antagonists such as diltiazem, nitrendipine and verapamil, with the exception that the segments of stomach fundus was not inhibited by verapamil. With the segments of uterus, but not those of other tissues, omega-CgTX (10(-7)-5 x 10(-6) M) significantly enhanced the contractile responses to various concentrations of ACh and high KCl. With rat ileum and guinea pig taenia coli segments, omega-CgTX (10(-9)-5 x 10(-6) M) did not induce a contractile response or have an enhancing effect. These findings suggest that omega-CgTX may have a calcium agonist-like effect on smooth muscles such as the stomach fundus and uterus of rats.

Acetylcholine↗
PubMed1987

A new agglutinin from the Tulipa gesneriana bulbs.

Two agglutinins with different agglutinating activity exist in Tulipa gesneriana bulbs. One is the T. gesneriana lectin which agglutinates yeasts as reported previously [Oda, Y. and Minami, K. (1986) Eur. J. Biochem. 159, 239-245]. The other agglutinin is a new one which agglutinates animal erythrocytes and was purified from the tulip bulbs using affinity chromatography on thyroglobulin-Sepharose 4B. The agglutinin agglutinated mouse and rat erythrocytes at a minimum concentration of 2 micrograms/ml and 30 micrograms/ml respectively, but did not agglutinate erythrocytes from other animals and yeasts even at a concentration of 1000 micrograms/ml. The agglutinin appeared homogeneous by disc gel electrophoresis at pH 4.3 and gel filtration. Its relative molecular mass was determined by gel filtration to be approximately 40,000. It was suggested that the agglutinin was composed of two different subunits of 26 kDa and 14 kDa by sodium dodecyl sulfate/polyacrylamide gel electrophoresis analysis. Binding of radioiodinated agglutinin to mouse erythrocytes indicated that the presence of a high-affinity site with a dissociation constant of 2.00 X 10(-9) M. In inhibition experiments thyroglobulin glycopeptides were the most potent inhibitors; thyroglobulin was also a potent inhibitor. Orosomucoid and mucin showed weak inhibition. The other glycoproteins, glycopeptides and sugars examined showed no inhibition.

Agglutination Tests↗
PubMed1987

[Specific inhibitory action of a novel antidepressant paroxetine on 5-HT uptake].

Effect of a novel antidepressant, paroxetine, on the uptake of serotonin (5-HT), noradrenaline (NA) and dopamine (DA) as well as on various neuro-receptors were investigated in comparison with those of the tricyclic antidepressants amitriptyline, chlorimipramine and imipramine. Paroxetine showed a potent 5-HT uptake inhibitory action, giving the NA/5-HT ratio of 886 in comparison with the ratios of 1.7, 15 and 1.5 for amitriptyline, chlorimipramine and imipramine, respectively. On the other hand, paroxetine showed almost no inhibitory action on the binding of the [3H]-labeled ligands examined in this study [( 3H]quinuclidinyl benzilate, [3H]5-HT, [3H]ketanserine, [3H]pyrilamine, [3H]dihydroalprenolol, [3H]prazosin, [3H]clonidine and [3H]spiroperidol). In contrast, the tricyclic antidepressants showed inhibitory action on a number of bindings and also revealed comparatively high affinities especially for muscarine, histamine-1 and alpha 1-adrenaline receptors responsible for the side effects. From the above findings, it can be concluded that paroxetine has only a weak affinity for various neuro-receptors and inhibits specifically 5-HT uptake.

Animals↗
PubMed1987

L-methionine enhances the contractile response to norepinephrine of rat vas deferens.

Under Ca-depleted conditions, the contractile responses of rat vas deferens in the presence of norepinephrine were not elicited until the addition of CaCl2. L-Methionine enhanced the contractile response of vas deferens in the presence of methylation blockers under these conditions. The enhancing effect of L-methionine on some other smooth muscles could not be determined because under Ca-depleted conditions, these muscles showed 60-80% of the maximal contractile response on addition of CaCl2 alone. These findings suggested that L-methionine has an enhancing effect on contraction of the rat vas deferens as it does on rat uterine muscle.

Animals↗
PubMed1987

Enhancement by L-methionine of contractile responses to acetylcholine and high KCl in uterine segment.

The contractile responses of isolated uterine segments from 17 beta-estradiol-3-benzoate-treated ovariectomized rats to acetylcholine (ACh) and high KCl in Ca-depleted modified Locke-Ringer solution on addition of CaCl2 were used as indicators of Ca2+ influxes through ACh receptor- and voltage-operated Ca2+ channels, respectively. L-Methionine (L-Met) significantly enhanced these responses. The enhancement depended on the time of treatment with L-Met and concentration of L-Met. 3-Deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL), which inhibit S-adenosylmethionine-dependent methylation, caused dose-dependent inhibition of these contractile responses to ACh and high KCl. These inhibitory effects of 3-DAA plus HCTL were significantly attenuated in the presence of L-Met. Protein carboxylmethyltransferase and phospholipid methyltransferase activities were detected in the isolated uterine segment under conditions similar to those in which the contractile responses were observed. 3-DAA plus HCTL inhibited these enzyme activities. These findings suggest that S-adenosylmethionine-dependent methylations of protein and/or phospholipid in isolated uterine segment are involved in the contractile responses to ACh and high KCl in Ca-depleted modified Locke-Ringer solution on addition of CaCl2.

Acetylcholine↗
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↗