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Volume 94 (1989)
- Issue 6 Pages 329-
- Issue 5 Pages 257-
- Issue 4 Pages 207-
- Issue 3 Pages 159-
- Issue 2 Pages 91-
- Issue 1 Pages 1-
Volume 94, Issue 4
Displaying 1-6 of 6 articles from this issue
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Machiko MATSUMOTO, Hiroko TOGASHI, Mitsuhiro YOSHIOKA, Hideya SAITO1989 Volume 94 Issue 4 Pages 207-222
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSThe role of serotonin (5-HT) in blood pressure (BP) regulation was reviewed. Central and peripheral 5-HT receptors can be divided into three receptor subtypes: 5-HT1 (5-HT1A, 5-HT1B, 5-HT1C), 5-HT2 and 5-HT3 receptors. The selective agonists and antagonists of these receptor subtypes are useful for investigating the BP regulation by 5-HT. The central 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) produced hypotension and decreases in sympathetic nerve activity (SNA). This suggests that central 5-HT may cause decreases in both BP and SNA via 5-HT1A receptors. Since the 5-HT2 receptor antagonist ketanserin, which has an antihypertensive effect, decreased SNA and the 5-HT2 agonist 1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) increased SNA, central 5-HT2 receptors may be connected with the 5-HT-induced increases in both BP and SNA. On the other hand, ketanserin's antihypertensive effects via its 5-HT2 receptor blocking action in the vascular system indicates that peripheral 5-HT may contribute to the initiation or the maintenance of elevated vascular resistance in several forms of hypertension including essential hypertension. However, ketanserin also possesses α1-adrenoceptor blocking action, and its precise antihypertensive mechanism has not been established. Further study of the antihypertensive mechanism of ketanserin will help clarify the precise role of 5-HT in BP regulation.View full abstractDownload PDF (13657K) -
Masami KOJIMA, Hiroshi KANETO1989 Volume 94 Issue 4 Pages 223-228
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSA simple and reliable method for the preparation of an ischemia-induced amnesic model was developed in mice and the model animals were employed for screening of the antiamnesic effect of drugs. Under light thiopental anesthesia the bilateral carotid arteries were exfoliated from the surrounding tissues. Each artery was threaded through a small polyethylene tube, and the incision was sutured, leaving the tip of the tube and both ends of the thread out of the skin. To prevent the tube from falling off, both ends of the thread was ligated at the tip of the tube. Cerebral ischemia was attained by pulling the artery into the tube, and the occlusion was rapidly released by cutting the ligation in the thread and taking off the tube. Twenty-four hours after the surgery, the animals were used for the one trial passive avoidance learning test. In ddY strain mice, the amnesic state was obtained by 5 to 30 min cerebral ischemia, which was applied immediately after the acquisition trial. Mice of the ICR strain were more sensitive to the ischemic treatment and 2 min occlusion of the carotid arteries resulted in a high degree of amnesia. A potent prolyl endopeptidase inhibitor, Z-thiopro-thiazolidine, and 2 novel pyrrolidone derivatives, p-chlorobenzyl-2-pyrrolidone-5-carboxylate and N-(2-pyridylmethyl)-2-pyrrolidone-5-carboxamide, improved the acquisition of the passive avoidance response in the ischemia-induced amnesic models.View full abstractDownload PDF (4082K) -
Hirohiko SAKAMOTO, Nobuharu YOKOYAMA, Takashi NISHIMOTO, Shigekatsu KO ...1989 Volume 94 Issue 4 Pages 229-236
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSThe effects of tricyclic antidepressant drugs on cardiac receptor binding sites and Ca2+ binding to cardiac sarcoplasmic reticulum were investigated in rats. 1) Quinupramine was found to possess higher affinity for muscarinic cholinergic receptor binding sites in brain and heart, compared with imipramine. 2) Repeated quinupramine treatment induced a significant increase in the Bmax value in cardiac muscarinic cholinergic receptors. 3) In imipramine treated heart, isoproterenol-induced stimulation of ornithine decarboxylase activity was significantly decreased compared with that in the vehicle control. 4) Repeated quinupramine and imipramine treatment caused a significant reduction of Bmax of 45Ca2+ binding in cardiac sarcoplasmic reticulum fractions. 5) After single quinupramine treatment, its concentrations in heart were higher than those in brain and plasma. 6) After the repeated quinupramine treatment, its concentration in heart was 2.4 times higher than that after single treatment. These results demonstrate that repeated tricyclic antidepressant drug treatment caused a functional impairment in Ca2+ binding sites of cardiac sarcoplasmic reticulum and adaptive changes of receptor binding sites.View full abstractDownload PDF (6258K) -
Shuichiro HAMANO, Hidetada KOMATSU, Shigeru IKEDA, Nobuo SAKURAGAWA1989 Volume 94 Issue 4 Pages 237-242
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSEffects of low molecular weight heparin (FR-860) were investigated on the arterio-venous (A-V) shunt model and on the in vitro blood coagulation system compared to conventional unfractionated heparin (UF-heparin) in rabbits. In the A-V shunt model, FR-860 (12.5^50 U/kg, i.v.) and UF-heparin (25 and 50 U/kg, i.v.) dose-related inhibited thrombotic formation in the tube of the A-V shunt at 30 min after starting blood circulation. Both FR-860 and UF-heparin dose-relatedly increased the anti-F.Xa activity at 5 min after starting blood circulation. However, FR-860 showed weaker effects in a prolongation of the aPTT, PT and thrombin time than UF-heparin in the A-V shunt model. Neither FR-860 nor UF-heparin had any influence on platelet aggregation. FR-860 also had a weaker effect in the prolongation of the plasma recalcification time, aPTT and PT than UF-heparin in vitro. FR-860 showed equipotent efficacy on the anti-F.Xa activity and had weak antithrombin activity compared to that of UF-heparin in vitro. These results suggest that the antithrombotic effect of FR-860 mainly depends on its anti-F.Xa activity but not on the antithrombin activity. Therefore, FR-860 is more efficient and lower in bleeding risk than UF-heparin in hemodialysis and thrombotic disorders.View full abstractDownload PDF (3876K) -
Shuichiro HAMANO, Mayumi KINUKAWA, Hidetada KOMATSU, Shigeru IKEDA, No ...1989 Volume 94 Issue 4 Pages 243-249
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSWe studied the effects of FR-860 on coagulative and fibrinolytic activities in human plasma compared to conventional unfractionated heparin (UF-heparin). Both FR-860 and UF-heparin dose-dependently prolonged the recalcification time, activated partial thromboplastin time, prothrombin time, factor Xa (F.Xa) clotting time and thrombin time. These effects of FR-860 were weaker than that of UF-heparin. FR-860 showed equipotent efficacy on the anti-F.Xa activity, and weak antithrombin activity compared to UF-heparin. FR-860 had no effects on the activity of ATIII and fibrinolytic activity. UF-heparin shortened the urokinase-activated euglobulin lysis time and showed antiplasmin activity, but did not influence the activities of ATIII, plasminogen and α2-plasmin inhibitor. UF-heparin decreased the fibrinogen level at higher doses. These efficacies of FR-860 were weaker than that of UF-heparin. These results suggest that FR-860 is more efficient and lower in bleeding risk than UF-heparin in clinical use.View full abstractDownload PDF (4453K) -
Masahisa KAWAKAMI, Ka BIAN, Noboru TODA1989 Volume 94 Issue 4 Pages 251-256
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSFelodipine [ethylmethyl 4-(2, 3-dichlorophenyl)-1, 4-dihydro-2, 6-dimethyl-3, 5-pyridinedicarboxylate], a new Ca2+ entry blocker, relaxed isolated canine arteries and veins precontracted with prostaglandin (PG) F2α, in a concentration-dependent manner. Felodipine dilated cerebral arteries predominantly over the other arteries. Relaxations by felodipine, in low concentrations, were greater in mesenteric vein strips than in mesenteric artery strips isolated from the same dogs. The inhibitory effect of felodipine in high concentrations (10-7 M or higher) were not reversed by repeated washing. In coronary arteries exposed to Ca2+-free media under anoxia, PGF2α and Ca2+ produced persistent contractions. Reoxygenation from anoxia elicited an additional contraction. Felodipine did not affect PGF2α-induced contraction in Ca2+-free media, but significantly reduced the contractions caused by Ca2+ and reoxygenation. These findings suggest that felodipine is a potent, long-acting Ca2+ entry blocker with characteristics such as a greater action on cerebral arteries and mesenteric veins than coronary and mesenteric arteries.View full abstractDownload PDF (4593K)
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