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Volume 102 (1993)
- Issue 6 Pages 355-
- Issue 5 Pages 301-
- Issue 4 Pages 257-
- Issue 3 Pages 161-
- Issue 2 Pages 59-
- Issue 1 Pages 1-
Volume 102, Issue 2
Displaying 1-8 of 8 articles from this issue
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Hideaki SADA, Takashi BAN, Yoshio EBINA1993 Volume 102 Issue 2 Pages 59-68
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSThe sodium channel plays essential roles in the initiation and propagation of action potentials (APs) in excitable tissues including the heart, nerves, and muscles. Na channels in these tissues undergo so-called activation and then inactivation upon step-depolarizations of the cell membrane. Hodgkin and Huxley, early in the 1950s, proposed a mathematical model to describe such events, which was based on voltage-clamp (V-C) data on axonal membranes. However, for the next 30 years or so since the pioneering work of the above workers, electrophysiological studies of the Na channel kinetics in the heart had relied exclusively on AP data (Vmax) as an indirect measure of the Na current instead of V-C data due to difficulty in determing V-C from the complex geometry of cardiac tissues. However, recent development of an isolation procedure for preparing single heart cells and the use of single patch-pipettes for high resolution V-C experiments on these cells have made direct recording of Na channel currents also possible in the heart. Voltage-clamp studies carried out for the last decade have provided several lines of evidence supporting the view that the Na channel properties in the heart of any animal species are somehow more complex than in the axonal membrane and hence showing that Hodgkin-Huxley model can not be directly applied to describe the Na channel behavior in the former type of tissues. Here, we review recent results from V-C studies on Na channel properties with special reference to the macroscopic Na current in cardiac tissues.View full abstractDownload PDF (1831K) -
[in Japanese]1993 Volume 102 Issue 2 Pages 69-76
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSDownload PDF (3571K) -
[in Japanese], [in Japanese]1993 Volume 102 Issue 2 Pages 77-83
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
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Tadashi KISHIMOTO, Yoshiaki OKAMIYA, Kumiko AOKI, Mikio OTA, Kenji HOS ...1993 Volume 102 Issue 2 Pages 85-100
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSThe antianginal effects of palonidipine, a novel 1, 4-dihydropyridine derivative, and nifedipine on various myocardial ischemic models were compared. (1) Palonidipine at 0.5 mg / kg, p.o. significantly inhibited vasopressin-induced ST depression of ECG in Donryu rats. This activity was about 5 times more potent than that of nifedipine and was long-lasting. (2) Palonidipine at 1 mg/kg, i.d. significantly inhibited ST depression induced by isoproterenol in Wistar rats. This activity of TC-81 was more potent than that of nifedipine. (3) Palonidipine at 3 itg/kg, i.v. produced an increase in regional myocardial tissue blood flow in the ischemic region of chronic coronary artery occluded dogs. (4) In isolated dog coronary artery, palonidipine at a concentration of 10-10M or greater inhibited the amplitude of 3, 4-DAP-induced cyclic contractions in a concentration-dependent manner. This activity was 10-30 times more potent than that of nifedipine. (5) An intracoronary injection of endothelin (30pmol/kg) reduced the coronary blood flow, subepicardial tissue blood flow, and subepicardial pH in anesthetized dogs.The ST elevation of ECG over 0.1 mV also occurred in 8 of 10 cases. In all the cases, ventricular extrasystoles were noted, and 9 out of 10 animals died. Pretreatment with palonidipine (3μg/kg, i.v.) inhibited endothelin-induced ischemic changes, with a potency greater than that of nifedipine. These results suggest that palonidipine may be useful for the therapy of angina-pectoris.View full abstractDownload PDF (4479K) -
Hideki TAKASE, Kazunori YAMAMOTO, Keizo ITO, Eizaburou YUMIOKA1993 Volume 102 Issue 2 Pages 101-112
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSWe studied the effects of berberine and Geranii Herba extract (GH) on different diarrheal models of mice, on the contractions of the isolated guinea pig intestinal smooth muscle and on the peristalsis in the rat intestine, comparing these effects with those of atropine (ATR) and papaverine (PAP). 1) Berberine significantly in hibited both the diarrhea induced by castor oil and that induced by BaCl2 at doses higher than 25 mg/kg, p.o., but did not inhibit diarrhea induced by pilocarpine or serotonin even at 250 mg/kg, p.o. GH exhibited a significant inhibition of BaC12 induced diarrhea. ATR prevented pilocarpine-induced diarrhea most strongly in diarrheal models. PAP significantly inhibited castor oil-, BaCl2-and pilocarpine-induced diarrhea, but not the serotonin-induced one. 2) Berberine inhibited ACh-or Ba2+-induced contractions of the ileum and colon at a concentration of about 10-5 g/ml, and PAP did so at about 10-6 g/ml, but GH (10-3 g/ml) failed to inhibit them. ATR prevented the ACh-induced contraction of the ileum and colon at concentrations 1/1000 of those needed to prevent the Ba 2+-induced one. On the other hand, berberine as well as PAP exhibited a noncompetitive inhibition of the contractile response induced by ACh, whereas ATR showed a competitive inhibition. 3) Berberine, GH, ATR and PAP showed significantly inhibited the spontaneous peristalsis in the intestine. These results suggest that berberine and GH have antidiarrheal action and that the mechanism of action of berberine may be somewhat differ from that of GH.View full abstractDownload PDF (4977K) -
Yukihiro IKOMA, Tetsuo AKAI, Yukie NAKATA, Kimio HARA, Helmut WACHTEL, ...1993 Volume 102 Issue 2 Pages 113-129
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSEffects of terguride, a 9, 10-dihydrogenated derivative of lisuride, on the central nervous system were investigated in rodents in comparison with those of lisuride. In vitro binding studies in rat brains showed that terguride, similar to lisuride, had a high affinity for D2-, 5-HT 1A-, 5-HT 2-, α1- and α2- receptors. Terguride, as does lisuride, induced hypomotility and yawning at low doses in rats, suggesting its presynaptic D2-agonist action. Terguride, unlike the postsynaptic D2-agonist lisuride, induced neither hypermotility nor stereotypy in rats and guinea pigs, but suppressed the hypermotility and stereotypy induced by apomorphine. Terguride suppressed haloperidol-induced catalepsy in rats and induced contralateral rotations in unilaterally 6-0HDA-lesioned rats, as does lisuride. These effects may be due to the postsynaptic D2 partial agonist action. Terguride, unlike lisuride, neither induced the serotonin syndrome nor generalized to the discriminative stimuli of the 5-HT1A-agonist 8-OH-DPAT in rats. Terguride did not induce head twitch in mice. Terguride blocked noradrenaline-induced lethality and clonidine-induced hypothermia at high doses in mice. Repeated ad-ministration of terguride did not affect the behavioral actions in rats. Thus, the effects of terguride on the central nervous system seems to be produced by mediation of the agonist and partial agonist actions at presynaptic and postsynaptic D2- receptors, respectively.View full abstractDownload PDF (3490K) -
(2) The vasodilator action of F-0401 in isolated canine arteries.Noriko KASE, Tetsuaki YAMAURA, Haruo OHNISHI1993 Volume 102 Issue 2 Pages 131-139
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSF-0401 ((+) - (E) -3- [4- (1-imidazolyl) methylphenyl] -2-propen-l-y1 methyl 1, 4-dihydro-2, 6-dimethyl-4- (3-nitropheny1) -3, 5-pyridinedicarboxylate) is a newly synthesized dihydropyridine derivative. We investigated the vasodilator action of F-0401 in isolated canine cerebral and peripheral arteries. F-0401 reduced KC1-induced contraction of the arteries in a concentration-dependent manner. The inhibitory action on cerebral arteries was greater than that on the peripheral ones. Its pD'2 values were as follows : Middle cerebral (8.3), basilar (8.1) > coronary (6.9) > femoral, renal, internal carotid, vertebral, mesenteric (6.0-5.5) arteries. The cerebrovascular-selectivity (the ratio of the pD'2 of the basilar artery to that of the femoral one) of F-0401 was 4, 25 and 40 times as large as that of flunarizine, nicardipine and nimodipine, respectively. F-0401 shifted to the right the concentration-response curve for CaCl 2 in the depolarized basilar artery (pA 2 value : 8.9). However, the reductions of 5-HT and PGF 2α-induced contractions by F-0401 in thisartery were very weak (pD'2 value : 5.9 and <4.5). These results suggest that F-0401 is a potent cerebrovascular-selective vasodilator and its effects were attributed to the inhibitory effect on the voltage-dependent Ca 2+ channels.View full abstractDownload PDF (1336K) -
Relation to its anti-tremorgenic actionYouichi HARA, Shin-ichi SUGIMOTO, Hideki ONO1993 Volume 102 Issue 2 Pages 141-151
Published: August 01, 1993
Released on J-STAGE: September 07, 2011
JOURNAL FREE ACCESSThe effect of arotinolol on the incomplete tetanic contractions of the cat soleus muscle was studied. Isoproterenol and epinephrine injected intravenously decreased the tension and degree of fusion of incomplete tetanic contractions of the soleus muscle in anesthetized cats. Intravenous arotinolol (>3μg/kgkg), propranolol (>30μg/kg) and pindolol (>3μg/kg) blocked the effects of isoproterenol and epinephrine, but atenolol (-300μg/kg), prazosin (0.1-10μig/kg) and phentolamine (10, 30μg/kg) did not block them. These results indicate that the receptors involved can be classified as of the β2-type. It is proposed that arotinolol may inhibit β2-adrenoceptors in the extrafusal muscle fibers of slow muscle, and thereby reduces the amplitude of tremor by changing the incomplete tetanic contractions of the muscle to the complete ones.View full abstractDownload PDF (4498K)
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