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Volume 52 (1990)
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Volume 52, Issue 1
Displaying 1-24 of 24 articles from this issue
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Tsutomu SUZUKI1990 Volume 52 Issue 1 Pages 1-10
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSPhysical and psychic dependence on opioids and CNS depressants in rodents were examined using the drug-admixed food (DAF) method. A comparison of several methods for developing physical dependence on opioids was made. The DAF method has the advantage of rapidly inducing a high degree of physical dependence without causing morbidity or mortality. When morphine-dependent rats were pretreated with several opioids, naloxone-precipitated weight loss was suppressed in a dose-dependent manner. A procedure for the development of severe physical dependence on CNS depressants was also established. Drug concentrations were rapidly increased until animals showed moderate to severe CNS depression, and then this condition was maintained for at least 10 days. With this procedure, animals became severely dependent on CNS depressants. Another technique, intermittent infusion, was developed that has been used to quantify shortacting CNS depressant dependence potential. The sedative effects of pentobarbital were used as an index in the determination of the injection intervals. These results suggest that the DAF method and the new approaches are useful tools for assessing the physical dependence potential of new drugs. Moreover, oral self-administration and weight pulling procedures were utilized along with the DAF method. Procedures for the oral self-administration of opioids and CNS depressants were established. Opioid-dependent rats pulled the weight to obtain the DAF even though they had free access to normal food. This weight-pulling procedure may be useful for assessing the degree of reinforcing effects for drugs in rats.View full abstractDownload PDF (537K) -
Ryoji KOJIMA, Mikio ITO, Yoshio SUZUKI1990 Volume 52 Issue 1 Pages 11-21
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSWe investigated the effect of pyridoxal-5'-phosphate (PALP) on tobramycin (TOB)-induced nephrotoxicity in rats. Paper electrophoretic analysis showed that in the mixture of TOB and PALP, the spot corresponding to TOB alone almost disappeared and the spot associated with TOB overlapped with that associated with PALP, although the spots of TOB alone and PALP alone were observed as single spots on the cathode and anode sides, respectively. The overlapping of both compounds indicated that TOB could directly interact with PALP in vitro. In the assay of TOB binding to renal brush border membranes (BBMs), PALP significantly inhibited the binding of TOB to BBMs by interacting with TOB outside of BBMs vesicles. Intrarenal TOB levels in rats receiving TOB and PALP were lower than those in rats given TOB alone. Combination with PALP markedly suppressed the urinary protein content, urinary N-acetyl-β-D-glucosaminidase activity and blood urea nitrogen content elevated by TOB, and also reduced the degree of TOB-induced renal tubular cell necrosis. These results indicate that PALP protects the rat kidneys from TOB-induced nephrotoxicity and that the protective effect of PALP may be due to the reduced intrarenal TOB concentration and less binding of TOB to BBMs induced by the interaction of PALP with TOB.View full abstractDownload PDF (649K) -
Minoru ODA, Yoshitaka INO, Kazunori NAKAMURA, Shigeru KURAMOTO, Kazuno ...1990 Volume 52 Issue 1 Pages 23-34
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSFUT-187, a newly synthesized compound, was studied on its inhibitory activities mainly on proteolytic enzymes, in comparison with those of FUT-175 and FOY-305, known serine protease inhibitors. FUT-187, as well as FUT-175 and FOY-305, had selective inhibitory activities on serine proteases including CIF, CIs, kallikrein, trypsin, plasmin and thrombin; its activities on these enzymes except Clr and pancreatic kallikrein were relatively lower than those of FUT-1 75 and FOY-305. Further studies were conducted focusing on complement-mediated reactions. In spite of its lower activities against Clr and Cls, inhibitions by FUT-1 87 on the complement-mediated hemolysis in vitro and in vivo were only a little weaker than or equivalent to that of FUT-1 75. FOY-305 was ineffective in these tests. Forssman shock in guinea pigs is known to be initiated by the activation of the complement system. The protective effect of intravenous or oral FUT-1 87 against this shock was definitely superior to that of FUT-175. Furthermore, FUT-187 inhibited changes accompanied with Forssman shock, such as increase in lung weight, the decrease in platelet counts and CH50, and histopathological changes. These results suggested that FUT-187 should be a more potent oral therapeutic agent than FUT-175 for various inflammatory diseases attributed to the excessive activation of the complement system followed by platelet aggregation.View full abstractDownload PDF (671K) -
Yoshimi IMURA, Zen-ichi TERASHITA, Yumiko SHIBOUTA, Yoshiyuki INADA, K ...1990 Volume 52 Issue 1 Pages 35-43
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSAA-2414, (±)-7-(3, 5, 6-trimethyl-1, 4-benzoquinon-2-yl)-7-phenylheptanoic acid, inhibited the aggregation of guinea pig platelets induced by a prostaglandin endoperoxide (PGH2) analogue, U-44069 and the specific binding of another analogue, [3H]U-46619 to washed guinea pig platelets with IC50 values of 3.1×10-7 and 8.2×10-9 M, respectively. AA-2414 competitively inhibited the contraction of rabbit aorta and pig coronary arteries induced by U-44069 with pA2 values of 8.3 and 9.0, respectively. AA-2414 also inhibited the contraction of rabbit aorta induced by PGF2α (pA2: 7.8) and the contraction of pig coronary arteries induced by PGF2α, PGD2 and 9α, 11β-PGF2 with pA2 values of 7.8, 8.6 and 7.8, respectively. But, AA-241 4 had no effect on the antiaggregatory effect of PGD2 on the aggregation of guinea pig platelets. In experiments with guinea pigs ex vivo, AA-2414 (0.1-1 mg/kg, p.o.) dose-dependently inhibited the platelet aggregation induced by U-44069; the inhibition at a dose of 1 mg/kg was 100% at 1 hr and was 89% even at 24 hr after the administration. The thromboxane (TX) A2/PGH2 receptor antagonistic action of AA-2414 was stereospecific. These results show that AA-2414 is a potent, orally active and long acting TXA2/PGH2 receptor antagonist. In addition, AA-2414 has PGF2α, PGD2 and 92α, 11β-PGF2 antagonistic effects.View full abstractDownload PDF (516K) -
Mayumi TSUJI, Kyoko KODAMA, Katsuji OGUCHI1990 Volume 52 Issue 1 Pages 45-49
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSEffects of S-adenosyl-L-methionine disulfate tosylate salt (SAMe-ST) and L-methionine (L-Met) on rat erythrocytes and primary cultured hepatocytes were studied. SAMe-ST in concentrations of 0.2 to 5.0 mg; ml protected erythrocytes from hypotonic hemolysis. Almost an identical level of protection was provided by SAMe chloride, suggesting that this protective effect is due to the SAMe moiety itself but not its sulfate or tosylate moiety. L-Met also showed a slight protective effect, but at higher concentrations, it slightly enhanced hemolysis. When the cultured hepatocytes were treated with SAMe-ST, the leakage of enzymes from the hepatocytes were significantly decreased compared with that in the control. L-Met also showed similar protective effects, but to a lesser degree than in the case of SAMe-ST. SAMe-ST significantly increased Na+, K+-ATPase activity. The present results indicate that SAMe remarkably inhibits hypotonic hemolysis and enzyme leakage from cultured hepatocytes and that its mechanism is probably related to a change in the membrane property.View full abstractDownload PDF (293K) -
Shigefumi SERIKYAKU, Michiko SAITO, Ryoichi ISHITANI1990 Volume 52 Issue 1 Pages 51-57
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSTo investigate the biochemical nature of temperature-induced highaffinity [3H]tryptamine binding sites, we subjected whole rat brain synaptic membranes to treatment with various protein-modifying reagents and examined the subsequent [3H]tryptamine binding properties of the membranes. Pretreatment of the membrane preparations with NEM, NBS, PCMB, PAPMA and MA, but not with iodoacetamide, DTT, glutathione and cysteine, reduced the [3H]tryptamine binding. In addition, to at least approx. 10-4 M, the inactivation properties of NEM, PCMB, PAPMA and MA, except for NBS, were temperature-dependent. Furthermore, it was revealed that the Scatchard plot of [3H]tryptamine binding in membranes pretreated with these thiol reagents conformed to a curved line, as well as in the case of the control membranes. Nonlinear regression analysis of these data showed that NEM decreased the Bmax values of both the high and low affinity binding sites with no significant alteration in the KD values, whereas PCMB, PAPMA and MA increased only the KD value of the high affinity sites, accompanying the decrease of the Bmax values of both sites. These results indicate that the temperature-induced high-affinity [3H]tryptamine binding molecule(s) is a thiol protein.View full abstractDownload PDF (363K) -
Hitoshi KONTANI, Tsutomu INOUE, Takeshi SAKAI1990 Volume 52 Issue 1 Pages 59-67
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSWe studied the effects of apomorphine (AM) on bladder motility in anesthetized rats in which Tyrode's solution was continuously infused into the bladder at a constant rate, inducing an almost constant rate of bladder contraction accompanying micturition. AM at a dose of 1 mg/kg, i.v., caused a hyperactive bladder response, during which micturition disappeared. AM (12.5 μg) for intracerebroventricular (i.c.v.) injection or 50 μg for intrathecal (i.t.) injection also caused a hyperactive response in about half of the rats. Supersensitization to AM appeared in reserpine-treated rats (2.5 mg/kg, i.p., 48 and 24 hr before the experiment). Haloperidol (1 mg/kg; i.v.) or SCH 23390 (5 mg/kg, i.v.) completely suppressed the hyperactive bladder response induced by AM (5 mg/kg, i.v.), and then the bladder contraction accompanying micturition reappeared after administration of these drugs. Pretreatment with sulpiride (100 mg/kg, i.p.) for 60 min, which hardly affected the bladder contraction induced by infusion of Tyrode's solution, suppressed the hyperactive bladder response induced by AM. These results suggest that the hyperactive bladder response induced by i.v.-injected AM results from synchronous stimulation of the micturition reflex centers in the brain stem and sacral cord and that the hyperactive bladder response is elicited via both D1 and D2 receptors.View full abstractDownload PDF (383K) -
Kunio AKAHANE, Yasuyuki FURUKAWA, Yasuyuki KARASAWA, Lei-Ming REN, Shi ...1990 Volume 52 Issue 1 Pages 69-79
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSPositive chrono and inotropic responses to denopamine (TA-064, (-)(R)-1-(p-hydroxyphenyl)-2-[(3, 4-dimethoxyphenethyl)amino] ethanol), a new and orally active cardiotonic agent, were investigated in the canine isolated right atrial or left ventricular preparation which was cross-circulated with blood from another support dog. Denopamine dose-dependently increased the sinus rate, right atrial and left ventricular contractile force. Denopamine was one to two orders of magnitude less potent than isoproterenol. The positive chrono and inotropic effects of denopamine in isolated, blood-perfused right atria were dose-dependently inhibited by treatment with propranolol and atenolol. The effects of denopamine were only slightly attenuated by ICI 118, 551 in doses which completely suppressed the positive chrono and inotropic effects of procaterol. The increases in sinus rate and atrial contractility induced by denopamine were partially but significantly attenuated by treatment with imipramine in a dose which suppressed the effects of tyramine and potentiated the effects of norepinephrine. These results indicate that denopamine is a highly selective beta-1 adrenoceptor agonist in isolated, bloodperfused dog heart preparations, and they also suggest a mild catecholaminereleasing activity through tyramine-like action in isolated right atria.View full abstractDownload PDF (594K) -
Akibumi NOGUCHI, Mitsuyuki TAKAMURA, Kenji YAMADA, Shohei TOU, Masahir ...1990 Volume 52 Issue 1 Pages 81-85
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSEffects of procaine on dibutyryl adenosine 3', 5'-cyclic monophosphate ((Bu)2cAMP)-, Ca2+ or forskolin-induced steroidogenesis were examined in isolated bovine adrenocortical cells. Procaine (<1.0 mM) caused a marked suppression of (Bu)2cAMP or forskolin-induced steroidogenesis in the absence of extracellular Ca2+, but did not affect on Ca2+-induced steroidogenesis in the cells. (Bu)2cAMP decreased the cell associated 45Ca2+. However, procaine (300 μM) inhibited this effect of (Bu)2cAMP. These results suggest that procaine may abolish (Bu)2cAMP-induced Ca2+ release from intracellular calcium store(s) and inhibits steroidogenesis.View full abstractDownload PDF (252K) -
Eiichi MAKINO, Tetsuo OHASHI, Hiromi TAKAHASHI, Hideo KATO, Yasuo ITO, ...1990 Volume 52 Issue 1 Pages 87-94
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSAntiallergic effects of 6-(1-pyrrolidinyl)-N-(1 H-tetrazol-5-yl)-2-pyrazinecarboxamide (HSR-6071), a newly synthesized agent, were investigated. The 48-hr homologous passive cutaneous anaphylaxis (PCA) in rats was inhibited in a dose-dependent manner by i.v. and p.o. administration of the agent (ED50=0.0096 mg/kg and 0.18 mg/kg, respectively). The IgE-mediated histamine release from rat peritoneal exudate cells was inhibited by HSR-6071, with an IC50 of 4.6×10-10 M. Regarding the non-immunological histamine release, HSR-6071 inhibited compound 48/80-induced, but not A23187-induced and spontaneous histamine release. On the other hand, an increase in vascular permeability induced by histamine, serotonin and bradykinin was unaffected by HSR-6071 in doses sufficient to inhibit PCA. In addition, the contractile responses of isolated guinea pig ileum to histamine, acetylcholine and serotonin were also unaffected by the agent even in a high concentration of 10-4 M. These results indicate that HSR-6071 possesses a potent antiallergic activity and that the inhibition of PCA by HSR-6071 may be due to the suppression of chemical mediators release from mast cells.View full abstractDownload PDF (384K) -
Shohei KASUGAI, Nozomi HASEGAWA, Hideaki OGURA1990 Volume 52 Issue 1 Pages 95-100
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSA simple colorimetric assay using MTT has been developed to monitor mammalian cell survival and proliferation in vitro. In this study we used a clonal fibroblastic cell line (RPC-C2A) from rat incisal dental pulp to examine the effectiveness of the colorimetric assay to test for the toxicity of eugenol, which is frequently used to treat inflammed dental pulp. A technical problem encountered was the insolubility of MTT formazan, produced by the activity of mitochondria dehydrogenases. Dimethyl sulfoxide (DMSO) seemed to be the best solvent. Doses of eugenol causing a 50% inhibition in the colorimetric assay were calculated as 0.6 mM and 1 mM for cells in the growing phase and for cells at confluence, respectively. These values exist in the concentration range reported in the previous studies. Although the correlation between spectrophotometric absorbance and cell number was not completely linear, this method could be used effectively as a simple preliminary assay to test for the toxicity of dental drugs and materials.View full abstractDownload PDF (323K) -
Katsuhiko TANIGUCHI, Yasusuke MASUDA, Koichiro TAKANAKA1990 Volume 52 Issue 1 Pages 101-108
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSSites of the inhibitory action of antiallergic drugs (azelastine, oxatomide, tranilast, repirinast and amlexanox) on human neutrophils were investigated by measuring leukotriene B4 formation, arachidonic acid release and superoxide generation. Results obtained in this study were as follows: (i) Formations of leukotriene B4 by neutrophils activated with a calcium ionophore (A23187) were effectively inhibited by all types of antiallergic drugs examined here, although the required concentrations were within a range of 20-200 μM. (ii) Releases of arachidonic acid from activated cells were diminished by azelastine and oxatomide that were classified as basic antiallergic drugs. On the contrary, acidic antiallergic agents including repirinast, amlexanox and tranilast enhanced the arachidonic acid liberation. (iii) Generations of superoxide from neutrophils activated with either phorbol 12-myristate 13-acetate or n-formyl-methionyl-leucyl-phenylalanine were effectively diminished only by the basic antiallergic drugs.View full abstractDownload PDF (453K) -
Keiji YOKOYAMA, Osamu YAGASAKI1990 Volume 52 Issue 1 Pages 109-114
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSIn the present study, we investigated the effects of various Ca2+ blockers on the release of acetylcholine (ACh) induced by nicotine, electrical field stimulation (EFS) and high-K+. Cd2+ markedly depressed the ACh release due to these stimuli. Verapamil inhibited the nicotine-induced ACh release remarkably and the EFS or the high-K+-induced ACh release to a lesser extent. Since the nicotine and the EFS-induced ACh releases were inhibited by procaine, the local anesthetic property of verapamil likely contributes in part to the inhibition. Diltiazem abolished the nicotine-induced ACh release completely but did not affect the EFS-induced release and significantly increased the high-K+-induced ACh release. These results suggest the absolute requirement for extracellular Ca2+ in the release of ACh induced by nicotine as well as EFS and high-K+. In addition, these stimuli may open the same Ca2+ channel to evoke ACh release.View full abstractDownload PDF (314K) -
Koichi NAGATA, Kazuho ABE, Chao-Hsiung WANG, Hiroshi SAITO, Norio MATS ...1990 Volume 52 Issue 1 Pages 115-121
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSCharacteristics of β-adrenoceptor in the tracheal smooth muscle of Suncus murinus (suncus) were studied in comparison with those of rats and guinea pigs. lsoproterenol induced concentration-dependent relaxation of suncus trachea. However, the maximal relaxation was very small, and about 1000 times higher concentration was necessary compared to the case of the guinea pig. The order of the sensitivity to isoproterenol and the maximal relaxation was guinea pig>>rat> suncus. Tracheae from younger suncus were more sensitive to isoproterenol, but the maximal relaxation was not significantly different from the results using adult animals. Forskolin, a direct activator of adenylate cyclase, relaxed tracheae to similar extents in the three species. Though the affinity of specific [3H]dihydroalprenolol binding was not significantly different, the maximal number of binding sites was in the order of rat>guinea pig>suncus. However, the differences in density of the binding among the three species were not as great as differences in isoproterenol-induced relaxation. These results suggest that 1) β-adrenoceptor-mediated relaxation of tracheal smooth muscle is not well-developed in the suncus and 2) the deficient relaxation is probably caused by insufficient coupling between adrenoceptors and adenylate cyclase.View full abstractDownload PDF (380K) -
Buichi FUJITANI, Korekiyo WAKITANI1990 Volume 52 Issue 1 Pages 123-130
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSAnti platelet and antithrombotic effects of OP-41483, a PG121 analog, were studied in experimental animals, and the following results were obtained: 1) With 10 min-intravenous infusion to guinea pigs, OP-41483 inhibited platelet adhesiveness and platelet aggregation at 300-1000 ng/kg/min and 1000 ng/kg/ min, respectively. In these effects, OP-41483 was 1-3 times more potent than carbacyclin and 3 times less potent than PGI2. 2) With oral administration to guinea pigs, OP-41483 given as its α-cyclodextrin clathrate (OP-41483 α-CD) inhibited platelet adhesiveness at doses higher than 1.0 mg/kg (expressed in terms of OP-41483), whereas PGI2 and carbacyclin did not at 10 mg/kg. OP-41483 α-CD also inhibited platelet aggregation after a single dose of 3 mg/kg and repeated doses of 3 mg/kg/day for 7 days. 3) In the electrically induced thrombosis model of guinea pig mesenteric artery, OP-41483 (300-1000 ng/kg/min, i.v.-infusion) and OP-41483 α-CD (1.0-3.0 mg/kg, p.o.) inhibited thrombus formation, but heparin (1.0-10 U, /kg/min, i.v.-infusion) did not. 4) In the rabbit extracorporeal circulation thrombosis model, OP-41483 (100 and 300 ng/kg/min, i.v.-infusion) inhibited thrombus formation in the extracorporeal shunt and prevented the decrease in platelet count, hematocrit and fibrinogen level in circulating blood. Heparin (1.0-3.0 U/kg/min, i.v.-infusion) also inhibited the thrombus formation and the decrease in fibrinogen level, but did not inhibit the decrease in hematocrit and platelet count.View full abstractDownload PDF (414K) -
Tomohisa HATTORI, Mikio ITO, Tadashi NAGAMATSU, Yoshio SUZUKI1990 Volume 52 Issue 1 Pages 131-140
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSWe investigated the antinephritic effects of TJ-8014, in comparison to dipyridamole, on crescentic-type anti-GBM nephritis in rats. When administration of test drugs was started from the heterologous phase (from the day after the anti-GBM serum injection), TJ-8014 at 2.0 g/kg/day, p.o., markedly inhibited the urinary protein excretion and elevations of plasma cholesterol and urea nitrogen levels as well as glomerular histopathological changes (i.e., crescent formation, adhesion and fibrinoid necrosis) throughout the 40-day observation period. TJ8014 at 0.1 and 0.5 g/kg/day, p.o., and dipyridamole at 0.4 g/day, p.o., inhibited only the histopathological changes. When treatment was started from the autologous phase (from the 22nd day after the anti-GBM serum injection) after the disease had been established, only the high dose of 5.0 g/kg/day of TJ-8014, p.o., was effective in improving the histopathological changes of the established nephritis, as assessed on the 53rd day. The !ow doses of TJ-8014 and dipyridamole were ineffective. These results suggest that TJ-8014 may be a useful Japanese herbal medicine against rapidly progressive glomerulonephritis, which is characterized by severe glomerular lesions with the extensive formation of crescents. Furthermore, the mechanisms of action of this medicine will be discussed.View full abstractDownload PDF (576K) -
Kazuo KOBAYASHI, Eiichi NAKAJIMA, Yoshiko KUBO, Yoshie YASUKAWA, Nobuy ...1990 Volume 52 Issue 1 Pages 141-148
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSThe average values of the local cerebral glucose utilization (LCGU) were approx. 35-110 μmol/100 g/min in various nuclei in the brain of shamoperated animals. The values, however, were decreased by 25-75% in all areas examined at 24 hr after 4-vessel occlusion (forebrain ischemia) for 0.5 hr. Particularly, the LCGU values in the forebrain nuclei such as the cerebral cortices and thalamus were severely reduced, while that in the nuclei in the midbrain and hindbrain such as the red nucleus, chochlear nucleus and vestibular nucleus were slightly reduced. In rats treated with S-adenosyl-L-methionine (SAM, 100 mg/kg, i.p.) every 1 hr for 6 times from the recirculation, however, the LCGU values were increased in all brain structures by 35-195% in the forebrain ischemic rat. A significant increase was observed in the cerebral neocortices, caudate-putamen, lateral septal nucleus, thalamic nuclei, substantia nigra, cerebellum and some other nuclei. In some forebrain structures whose LCGU were mildly reduced to approx. 60-70% by the ischemia, SAM recovered the LCGU to more than 90% of the value in the sham-operated group. Thus it was concluded that SAM ameliorated widely ischemia-induced reduction of LCGU in the rat.View full abstractDownload PDF (431K) -
Ichiro NISHIYAMA, Tomoko FUJII1990 Volume 52 Issue 1 Pages 149-153
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSDevelopmental changes in calcitonin (CT) secretory capacity of C-cells were studied by using primary cultures prepared from the thyroid glands of rat fetuses at 1 6th, 1 8th and 20th day of gestation and the thyroid glands of 28-day-old rats. Both CT content of C-cells and high Ca2+-stimulated CT secretion increased with the age of the rats. The ratio of secreted CT to the CT content of C-cells also increased according to the age. These results demonstrated the functional development of C-cells during the fetal period.View full abstractDownload PDF (235K) -
Seiji ICHIDA, Kazuo YOSHIOKA, Shunji ARIYOSHI, Takashi FUJISUE1990 Volume 52 Issue 1 Pages 154-159
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSAcetylcholine (ACh)- and high KCI-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 (LMet). 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 KCI 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 KCI is mainly due to an increase in Ca2+ uptake into the uterine muscle.View full abstractDownload PDF (282K) -
Kenji YOGO, Shingo YANO, Kazuo WATANABE1990 Volume 52 Issue 1 Pages 160-163
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSIn the isolated rat stomach perfused with Krebs-Henseleit solution at 36°C, endothelin induced vasoconstriction in a dose-dependent manner. The threshold dose for inducing vasoconstriction was very small, and the pressor response to a bolus injection at 0.1 nmol lasted more than 1 hr. I n contrast, the vasoconstrictor effects of noradrenaline and serotonin were transient. The magnitude of the maximal response to endothelin was almost the same as that to noradrenaline, but greater than that to serotonin. The pressor response to serotonin, but not noradrenaline, was greatly augmented after pretreatment with endothelin. These results suggest that endothelin causes a long-lasting vasoconstriction, which would be associated with its ulcerogenic activity, especially in combination with other vasoactive agents under some pathophysiological conditions.View full abstractDownload PDF (217K) -
Yoshimi KUWAHARA, Yoko SUNAGAWA, Yoshimi IMOTO, Susumu OKABE1990 Volume 52 Issue 1 Pages 164-166
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSWe examined the effects of orally administered human epidermal growth factor (hEGF) on healing of acetic acid-induced gastric ulcers in rats. hEGF, given twice daily at 30 and 100 μg/kg for 2 weeks or at 100 μg/kg for 4 weeks to rats with ulcers, had no effect on natural healing or the gastric secretion, delayed one caused by indomethacin. Oral hEGF had no effect on basal histamine-stimulated gastric secretion, and stomach weight. These results indicate that oral hEGF has no biological activity on the pathophysiology of the stomach.View full abstractDownload PDF (178K) -
Yuta KOBAYASHI, Keisuke HATTORI1990 Volume 52 Issue 1 Pages 167-169
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSEffects of NG-nitro-L-arginine (NO 2Arg), a guanidinonitro arginine derivative, on acetylcholineinduced relaxation of rabbit thoracic aorta ring preparation were studied. Relaxation by acetylcholine was inhibited by NO2Arg dose-dependently and the maximum relaxation with 10 μM NO2 Arg was reduced to 10.1±4.3% (n=5). L-arginine (10 μM) did not affect the acetylcholine-induced relaxation. Relaxation by glyceryltrinitrate or papaverine was not affected by NO2Arg. These results indicate that NO2Arg is a novel inFiibitor of endothelium-derived relaxation.View full abstractDownload PDF (147K) -
Noboru TODA, Tomio OKAMURA1990 Volume 52 Issue 1 Pages 170-173
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSTreatment with L-NG-monomethyl arginine (L-NMMA) increased the vasoconstriction induced by adrenergic nerve stimulation in perfused dog mesenteric artery segments and suppressed the relaxant response to transmural nerve stimulation in dog cerebral artery strips, the effects of L-NMMA being reversed by L-arginine. The observed changes in nerve function may be associated with the inhibition of synthesis of nitric oxide.View full abstractDownload PDF (194K) -
Yoshio GOSHIMA, Shinichi NAKAMURA, Yoshimi MISU1990 Volume 52 Issue 1 Pages 174-177
Published: 1990
Released on J-STAGE: August 25, 2006
JOURNAL FREE ACCESSIn rat hypothalamic slices, antagonism by L-DOPA methyl ester and (-)-propranolol against L-DOPA-induced facilitation of endogenous noradrenaline (NA) release was characterized under the inhibition of dopadecarboxylase. L-DOPA at 10 nM to 1 μM facilitated the evoked NA release in a concentration-dependent manner. L-DOPA methyl ester (3, 10 and 30 nM) progressively shifted the concentration-release curve for L-DOPA to the right: Schild plots gave a straight line with a slope of 1.00 and pA2 was 8.9. This antagonistic action was not mimicked by L-phenylalanine, a substrate for L-DOPA transport system. In contrast, 10 and 100 nM propranolol concentration-dependently reduced the maximal effect of LDOPA without rightward shift of the concentration-release curve. L-DOPA methyl ester is a potent competitive antagonist for the action of L-DOPA, and the recognition site of L-DOPA differs from presynaptic β-adrenoceptors.View full abstractDownload PDF (226K)
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