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Volume 82 (1983)
- Issue 6 Pages 411-
- Issue 5 Pages 303-
- Issue 4 Pages 223-
- Issue 3 Pages 171-
- Issue 2 Pages 103-
- Issue 1 Pages 1-
Volume 82, Issue 4
Displaying 1-6 of 6 articles from this issue
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Kohsuke UCHIDA1983 Volume 82 Issue 4 Pages 223-235
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSPharmacological characteristics of the post-junctional adrenoceptors in the muscularis mucosae of the guinea-pig esophagus were examined in vitro. In the presence of propranolol (3 μM), all catecholamines, phenylephrine and methoxamine produced a weak contraction of the isolated muscularis mucosae. The order of potency of the contractile response was adrenaline > noradrenaline > methoxamine > phenylephrine and much weaker isoproterenol, dopamine and clonidine. The contractile responses to noradrenaline (10 μM) and adrenaline (10 μM) were markedly inhibited by phentolamine (3 μM), prazosin (3 μM), indomethacin (1 μM), aspirin (100 μM) and polyphloretin phosphate (30 μg/ml), and slightly by yohimbine (3 μM). On the other hand, all catecholamines and terbutaline produced relaxation of the isolated muscularis mucosae which was maximally contracted with carbachol (3 μM) in the presence of phentolamine (10 μM), in a concentrationdependent manner. The order of potency of the inhibitory response was isoproterenol > noradrenaline > adrenaline and much weaker terbutaline and dopamine. The inhibitory responses to catecholamines were competitively antagonized by three β blockers, being in the following order of potency as estimated by their pA2 values: propranolol > atenolol ?? butoxamine. The pretreatment of the tissue with indomethacin (1 μM) did not modify the inhibitory responses to catecholamines. These results suggest that the guinea-pig esophageal muscularis mucosae has excitatory α1 adrenoceptors and inhibitory β1 adrenoceptors, and the α1, but not β1, adrenoceptors may link with the endogenous arachidonic acid cascade.View full abstractDownload PDF (5754K) -
Kazuo WATANABE, Hiroshi WATANABE, Masaki MAEDA-HAGIWARA, Rumi KANAOKA1983 Volume 82 Issue 4 Pages 237-245
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSEffects of tizanidine, a centrally acting muscle relaxant, on gastric acid secretion and gastric ulcers were studied in the rat. Tizanidine (5 mg/kg, s.c.) did not influence basal acid secretion, but inhibited the centrally stimulated acid secretion in anesthetized rats. Intraduodenal administration of tizanidine (10 mg/kg) also inhibited the centrally stimulated acid secretion. The compound potentiated bethanechol-induced acid secretion at 10 mg/kg, s.c. Clonidine was found to have similar effects to tizanidine at the lower dose. Both tizanidine and clonidine inhibited basal acid secretion at a relatively low dose in conscious rats. Tizanidine (5 mg/kg, s.c.) did not modify indomethacin and stress-induced ulcers, but Shay ulcers were slightly inhibited by the drug. Indomethacin ulcers were significantly inhibited by 10 mg/kg, s.c., 10 mg/kg, p.o. or 20 mg/kg, p.o. of tizanidine. Clonidine also was found to be a strong inhibitory agent of indomethacin-, stress and Shay-ulcers. These results suggest that similar to clonidine, a high dosage of tizanidine influences gastric acid secretion and gastric ulcers, although the activity is lower than that of clonidine.View full abstractDownload PDF (3655K) -
Hiroshi WATANABE, Sunao HATA, Kazuo WATANABE1983 Volume 82 Issue 4 Pages 247-257
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSIn order to elucidate pharmacological properties of rotational behaviour produced by unilateral electrical stimulation of the substantia nigra, effects of 6-hydroxydopamine treatment, dopamine receptor antagonists and agonists were investigated in the rat. Dopamine and its metabolites in the striatum were estimated after the stimulation. Intranigral treatment of 6-hydroxydopamine remarkably inhibited rotational behaviour induced by electrical stimulation. Antipsychotic drugs, 1 mg/kg haloperidol i.p. and 1 mg/kg pimozide i.p., decreased the behaviour by 50% of the control level. Sulpiride and metoclopramide did not exert significant influences on the behaviour. The dopamine receptor agonist apomorphine, 0.5 and 1 mg/kg s.c., markedly suppressed the stimulation-induced rotation, although it produced stereotypy, i.e. sniffing and gnawing. Bromocriptine, 10 mg/kg i.p., also suppressed rotational behaviour and produced locomotor activation without electrical stimulation. Methamphetamine did not have significant effects on the behaviour. Unilateral electrical stimulation of the substantia nigra produced an increase in the content of dopamine metabolites in the ipsilateral striatum of the rat pretreated with probenecid. These results suggest that the nigrostriatal dopaminergic system plays an important role in rotational behaviour produced by the electrical stimulation, and dopamine receptor agonists suppress the behaviour through a stimulating effect on the presynaptic dopamine receptor.View full abstractDownload PDF (4843K) -
Kazuki MATSUNAGA, Motohiko UEDA1983 Volume 82 Issue 4 Pages 259-266
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSThe development and mechanism of acute tolerance to hypotension produced by pindolol in conscious SHR were examined. At a daily dose of 3 mg/kg, i.p., the hypotensive effect of pindolol (50±4 mmHg) on the first day was attenuated to 12±2 mmHg on the fourth day. The development of this acute tolerance was not reduced by combined administration with captopril or trichlormethiazide. The hypotensive effect of pindolol was not reduced by repeated administration of isoproterenol. Thus, activation of the renin-angiotensin system, fluid retention and β-adrenoceptor subsensitivity seemed to be ruled out from the mechanism of this acute tolerance to pindolol. SHR tolerant to pindolol displayed marked hypotensive effects to prazosin, clonidine, hydralazine, nifedipine and captopril, which were similar to those in saline-treated SHR. However, the depressor response to isoproterenol was markedly reduced in SHR tolerant to pindolol. The correlation between the hypotensive responses to isoproterenol (X) and pindolol (Y) in these SHR could be expressed by: Y=1.00X+0.56, γ=0.837 (P<0.001). Therefore, acute tolerance to pindolol seemed to be mainly due to “ autoblockade” by the remaining pindolol in the body.View full abstractDownload PDF (3654K) -
Yutaka GOMITA, Michio MORII, Yasuyuki ICHIMARU, Minehiro MORIYAMA, Sho ...1983 Volume 82 Issue 4 Pages 267-292
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSBehavioral and electroencephalographic effects of clobazam (CBZ), a 1, 5 benzodiazepine, were investigated in mice, rats and rabbits and compared with the effects of diazepam (DZP) and chlordiazepoxide (CDP). In EEG studies of rabbits, CBZ, DZP and CDP at doses of 2-10 mg/kg, i.v., caused a drowsy pattern, i.e., high voltage slow waves in the frontal cortex and the desynchronization of hippocampal theta wave. EEG arousal responses induced not only by auditory stimulation but also by electric stimulation of the mesencephalic reticular formation were inhibited by CBZ; CBZ was less potent than DZP, but more potent than CDP. On hypothalamic self-stimulation behavior of rats, low rate responses induced by low current brain stimulation, VI or DRL procedure were increased by oral administration of the three drugs. CBZ was less potent than DZP in the above respondings, but the same potency as CDP in VI or DRL responding and more potent in low rate responding induced by low current stimulation. The preventive effect of CBZ on MES convulsion in mice was less potent than DZP, but 2.5 times as potent as CDP. The preventive effect of CBZ was 1.3 times as potent as DZP and 2.5 times as potent as CDP. CBZ reduced the hyperemotionality of olfactory bulbectomized rats, and this effect was less than DZP in suppressing muricide. The muscle relaxant effect of CBZ in inclined screen and rotarod tests of mice was less than that of DZP. CBZ was 2.2 times as potent as CDP in potentiating thiopental sleep in mice, but less than DZP. These results indicate that CBZ is qualitatively similar to 1, 4 benzodiazepines, DZP and CDP, and is more potent than CDP, but less potent than DZP.View full abstractDownload PDF (9667K) -
Masahiro IIZUKA, Makizo HIRABAYASHI1983 Volume 82 Issue 4 Pages 293-301
Published: 1983
Released on J-STAGE: March 07, 2007
JOURNAL FREE ACCESSCharacteristics of changes in ambulatory activity after repeated administration of morphine, 5, 10 or 20 mg/kg s.c., were investigated in male mice of dd strain. The drug was administered 10 times at intervals of 1, 3-4 or 7 days, and the ambulatory activity of each mouse was measured by a tilting-type round activity cage with a 25 cm diameter for 180 min after each administration. Morphine, 5-20 mg/kg induced a dose-dependent increase in the ambulatory activity, and this effect attained to a peak at 60-90 min and persisted for 120-180 min after the administration. An augmentation of sensitivity (a reverse tolerance) to the ambulation-increasing effect of morphine was induced by the repeated administration of 10 and 20 mg/kg morphine, regardless of the intervals. The reverse tolerance achieved the maximum on the 5-6th administration day, and almost the same level of sensitivity was maintained until the 10th administration day. There was no significant difference in the activity counts at the peak time among the groups of mice varing the administration intervals. However, the persistence of increased ambulatory activity tended to be longer in the group of mice given morphine at intervals of 7 days than in the group given it at intervals of 1 day. The reverse tolerance, once produced, attenuated 2 months after the cessation of the repeated administration. However, the ambulatory activity counts did not return to those on the 1st administration day. In contrast, development of reverse tolerance to the ambulation-increasing effect of morphine could not be observed when mice were put into a glass jar, in which the ambulation was completely restricted, for 180 min after each administration. The factors involved in the production of reverse tolerance to morphine are discussed.View full abstractDownload PDF (4790K)
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