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Volume 33 (1983)
- Issue 6 Pages 875-
- Issue 5 Pages 687-
- Issue 4 Pages 507-
- Issue 3 Pages 309-
- Issue 2 Pages 151-
- Issue 1 Pages 1-
Volume 33, Issue 3
Displaying 1-16 of 16 articles from this issue
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Ken'ichi MATSUNAMI, Ikuma HAMADA1983 Volume 33 Issue 3 Pages 309-322
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe neuronal activity in the motor cortex of the rhesus monkey was investigated in three different tasks performed with finger, wrist, and arm movements. A total of 125 neuronal activities were analysed. They were classified into five groups in terms of muscular contractions provoked by intracortical stimulation; neurons related to contractions of finger, wrist, elbow, shoulder, or trunk muscles. The neuronal activities in three tasks performed with finger, wrist, or arm movements were investigated for each group. Most of the neurons related to the contractions of elbow, shoulder, or trunk muscles were associated solely with arm movement. Smaller numbers of neuronal activities changed their firing frequencies in association with two or three tasks. Neurons related to the contractions of finger and wrist muscles showed various firing patterns in the three tasks; some responded to a single task with wrist or arm movement, while others changed their activities in association with more than one task. The presence of multi-task related neurons is discussed with respect to the multisegmental termination of corticospinal axons in the spinal cord.View full abstractDownload PDF (1131K) -
Norio AKAIKE, Toshikazu KIYOHARA, Yasuo OYAMA1983 Volume 33 Issue 3 Pages 323-336
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSCentral nervous system (CNS)-induced suppression on the muscle Na-pump activity was studied in soleus (SOL) muscles of hypokalemic rats. Peripheral nerve section, cervical soleus and brainstem transection, decerebration, and cortical spreading depression with 20% KCl activated the Na-pump in SOL muscles during hypokalemia. Blockage of the nerve conduction by tetrodotoxin (TTX) also activated the Na-pump in SOL muscles. The activation of Na-pump after the denervation was completely abolished by the pre-treatment of ouabain. However, the muscle cation contents were not affected by the injection of curare and atropine. The activation of Na-pump in the muscles after denervation in the curarized hypokalemic rats was completely removed by electrical stimulus of the distal nerve stump of cut sciatic nerve. α-Adrenoreceptor antagonists (phenoxybenzamine, phentolamine and dibenamine, and prazosin) stimulated the Na+ and K+ transports in the SOL muscles during hypokalemia while β-adrenoreceptor antagonist (propranolol) had no effect. The denervation effect on SOL muscle cation contents was not affected with or without the presence of propranolol. It is concluded that CNS acts to inhibit the Na-pump mechanism in SOL muscles of hypokalemic rats and the inhibition is achieved by the apparent release of catecholamines onto muscle following neural activity. Thus, the CNS-induced suppression on the muscle Na-pump is prevented by denervation and by treatment with drugs that block either nerve conduction or α-adrenoreceptor.View full abstractDownload PDF (1104K) -
Tetsuro SAKAI, Akihiko HIROTA, Shiroh FUJII, Kohtaro KAMINO1983 Volume 33 Issue 3 Pages 337-350
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe propagation of spontaneous action potentials in 7-9 somite embryonic pre-contractile chick hearts was measured optically using a potential -sensitive merocyanine-rhodanine dye. Spontaneous optical signals, corresponding to action potentials, were recorded simultaneously from 8-16 different sites of the primitive embryonic heart. Short delays were observed in the time of occurrence of optical signals obtained from the different regions. We have found (i) switching phenomena: the site exhibiting pacemaking priority was first situated in the right pre-atrium, thereafter it switched over to the left pre-atrium, or vice versa, and (ii) double pacemakers: two different pacemaking areas were situated independently in the right and left pre-atrial portions of the heart. On the basis of analysis of such behavior, it was concluded that the regional priority of the pacemaking activity is not rigid but is flexible, that and the direction of the spread of excitation is adaptable to the circumstances in the early embryonic heart.View full abstractDownload PDF (1013K) -
Masahiro AOMINE, Makoto ARITA, Tatsuto KIYOSUE, Sunao IMANISHI1983 Volume 33 Issue 3 Pages 351-365
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe relationship among Na, K-ATPase activity, ATP and inorganic phosphate (Pi) concentrations in functionally different regions of cardiac and skeletal muscles were studied in the Japanese monkey (Macaca fuscata). The activity of Na, K-ATPase was determined by the method of Fiske and SubbaRow, and the concentrations of ATP and Pi, by isotachophoresis. The ATP concentrations in several regions of cardiac and skeletal muscles correlated positively with the Na, K-ATPase activities and Pi, concentrations, whereas there was no significant correlation between the Na, K-ATPase activities and the Pi concentrations. Therefore, the ATP concentrations in functionally different regions of the tissues seemed to be a feasible measure of Pi concentrations and the Na, K-ATPase activities. The Na, K-ATPase activity was significantly higher in the epicardium than in the endocardium of the ventricle. The post-overdrive hyperpolarization was compared in these two tissues, using microelectrode methods. The hyperpolarization which followed overdrive stimulation (3.3-3.8Hz) in the epicardium exceeded that in the endocardium, and was attributed to the difference in Na, K-ATPase activity. Our findings suggest that tissues with a higher Na, K-ATPase activity may have a more potent Na, K-pump activity, in association with higher tissue concentrations of ATP and Pi.View full abstractDownload PDF (1054K) -
Takehiro YAHATA, Yoshiaki HABARA, Akihiro KUROSHIMA1983 Volume 33 Issue 3 Pages 367-376
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSAfter 30min infusion of glucagon or noradrenaline, blood flow through brown adipose tissue (BAT) from various sites was investigated with the aid of 113Sn-labeled microspheres under hexobarbital anesthesia in cold-acclimated (CA), heat-acclimated (HA), and warm control (WC) rats. Glucagon increased cardiac output in both CA and HA, while noradrenaline increased it in HA but not in CA. Blood flow through BAT as well as the fractional distribution of cardiac output to BAT increased by glucagon dose-dependently and reached a maximum level in a dose of 2μg/min. These glucagon-induced responses were significantly higher in CA and smaller in HA as compared with WC. Noradrenaline in a dose of 2μg/min caused larger responses than glucagon in all groups. Glucagon- or noradrenaline-induced blood flow per unit weight of BAT increased or tended to increase by cold acclimation. These results suggest that an in vivo enhanced glucagon-induced thermogenesis in cold-acclimated BAT is partly due to an increased blood flow through this tissue.View full abstractDownload PDF (771K) -
Junko NITTA, Tomiyasu KOYAMA, Yuji KIKUCHI, Yoshio SHINDO1983 Volume 33 Issue 3 Pages 377-390
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe possibility of measuring erythrocyte flow velocity by means of a grating laser microscope has been examined in an in vitro test using erythrocytes smeared on glass plates and in vivo using microvessels in the web of a frog foot. Magnified projections of flowing erythrocytes are spatially filtered by a simple glass plate grating and then detected by a photomultiplier. Output signals from the photomultiplier are first electronically filtered so as to yield oscillating burst-like wave signals. Moving erythrocytes resulted in burst-like oscillation in output signals whose wave period (T) changed with their velocities. These results suggest that the velocity (V) of erythrocytes could be given by V=d/MT, where d and M represent the grating constant and the optical magnification, respectively. The requirement for the establishment of this relation was examined by the microscopic observation of smeared erythrocyte preparation. It was shown that the flow velocity of erythrocyte could be measured even when the size of magnified images of erythrocytes strongly exceeded the value of d and even when many erythrocytes existed.
A preliminary experiment to confirm the possibility of methodological adaptation was made by measuring the flow velocity in venules of foot web of frogs. Heart rate increased in all six frogs studied when the frog body was warmed. However, the peripheral flow velocity increased only in three frogs, while it remained almost unaffected in the other three. This result suggests that the frog peripheral microcirculation is affected by complicated intrinsic factors.View full abstractDownload PDF (1346K) -
Machiko SHIRAHATA, Yoshikazu OKADA, Ishio NINOMIYA1983 Volume 33 Issue 3 Pages 391-401
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSWe recorded renal nerve activity (RNA) together with arterial pressure (AP) and heart rate (HR) in 24 Wister rats anesthetized with nitrous oxide to investigate the effects of ketamine on the sympathetic nerve activity and the cardiovascular dynamics. The magnitude and time course of the responses to four graded doses of ketamine (1, 5, 10, 25mg/kg) were studied in 19 rats. RNA responded biphasically, initially decreasing dose-dependently to minimal values of 89±4.4, 77±8.2, 54±5.2, and 17±3.7% of control for 1, 5, 10, and 25mg/kg, respectively, and then increasing above control dose-independently. AP showed a biphasic response. HR first decreased dose-dependently but then increased slightly. In the remaining five rats, we compared the effects of ketamine 5mg/kg on RNA, AP, and HR before surgical baroceptor denervation with those after the denervation. The denervation abruptly increased RNA, AP, and HR. Ketamine decreased RNA, AP, and HR in the denervated state and returned them to pre-ketamine values without overshoot. The finding that in the nerve intact state ketamine produced the characteristically biphasic response of RNA could be explained by the following mechanisms: (1) ketamine depresses the vasomotor center causing the initial decrease in RNA; (2) ketamine depresses the inhibitory effects of baroreflex causing the successive increase in RNA. The biphasic change in AP could be partly attributed to biphasic responses of RNA to ketamine.View full abstractDownload PDF (857K) -
Atsuko YATANI, Masayosi GOTO1983 Volume 33 Issue 3 Pages 403-415
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSWhen the electrical properties of single, isolated, rat ventricular cells at low pH were examined, the amplitude of the action potential and its duration were found to decrease at low pH (<5.5). In voltage clamp experiments, the low pH depressed IS and slowed the inactivation process, yet the outward currents reflecting the plateau range of the action potential were not affected. The I-V curve of IS shifted to less negative potentials at low pH. Similar results were obtained in ISr and IBa at low pH.
The alteration of the action potential of single ventricular cells at low pH is attributed to the suppression of IS. The mechanism of this reduction of IS might be due to the presence of a surface potential capable of affecting gating and permeation mechanisms of IS. channel or to the protonation of some acidic group that must be ionized for the IS channel to function normally.View full abstractDownload PDF (1072K) -
Tsunenobu TERANISHI1983 Volume 33 Issue 3 Pages 417-428
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSOne type of light-induced response (photopic L-type S-potential) recorded from isolated carp (Cyprinus carpio) retinas was identified by its spectral response and later confirmed by morphological localization of the recorded sites ionophoretically marked by a fluorescent dye, Lucifer yellow. Such L-type S-potentials could be recorded from the soma and from the axon terminal of external horizontal cells. The spatial property of the S-potentials from the soma was compared with that recorded from the axon terminal by enlarging the diameter of a light spot (0.25 to 4.0mm) and by displacing the spot (0.5mm dia.) along a straight 4-mm line which passed over the recording point at the middle. The half decay distance of decremental amplitude with spot displacement was significantly (P<0.001) shorter in recordings from the soma than from the axon terminal, indicating that the spatial summation is less in the soma than in the axon terminal. The spatial summation was found to be greater in response to longer wavelengths than to shorter wavelengths for the two parts of the cell. Therefore, the soma and axon terminal appear to function as a single unit with respect to spectral information, but as two separate units with respect to spatial information. Electrical and dye couplings are assumed to take place at two different (cell body and axon terminal) levels, possibly being separated by the high resistance of the slender axon in the carp retina.View full abstractDownload PDF (1007K) -
Hiroshi KAWATA1983 Volume 33 Issue 3 Pages 429-448
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of twitch trains on the contractility of succeeding tetani were investigated in the frog toe muscle. The changes in isometric tension and its first derivative were analyzed. Tetani of 1 sec duration were induced every 5min and trains of twitches (less than 250) with 0.1 to 3Hz were interposed between two successive tetani. A twitch train which clearly shows an ascending staircase exerted at least three different effects on the following tetani. These were a rapidly decaying potentiation (P1), a slowly decaying potentiation (P2), and an inhibitory effect (I) which was regarded as fatigue. These after-effects were modified by various interventions. Increasing of the twitch frequency at a constant number of stimuli augmented both the potentiating and the inhibiting effects. When the bath temperature was lowered to 4°C, the potentiation was masked by a marked inhibition. At a higher temperature (28°C) the potentiating effect was facilitated. Prolonged perfusion of low concentration (0.5mM) of caffeine mimicked the effects of low temperature. Effects of twitch train on the contracture induced by 5mM caffeine were examined and it was found that the repetitive twitches had no effect on the following caffeine contracture. Although the exact mechanism for these after-effects was not clear, it was assumed that the intracellular calcium turnover may play some role in the observed phenomena.View full abstractDownload PDF (1322K) -
Kiyokazu KITAMURA, Midori SHIMAOKA, Hideji MATSUI, Miharu MIYAMURA1983 Volume 33 Issue 3 Pages 449-458
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe present study was undertaken to examine whether or not there were any differences between untrained and trained subjects in the changes of blood flow in the ipsilateral and contralateral lower limbs after isometric exercise. Blood flow of the thigh and calf in both right and left legs were measured simultaneously before and after isometric contraction with mercury-in-silastic strain gauge venous occlusion plethysmography. In the present study, the main pattern of blood flow responses in the active and non-active limbs was strikingly similar in all subjects : a significant fall in blood flow immediately after isometric contraction at a force of about 50% of maximal muscle strength for 15sec was observed in the non-active lower limbs. Peak blood flow of the exercised thigh in the trained group was significantly higher than that in the untrained ones. From these results, it was suggested that higher blood flow after isometric exercise in the trained subjects may be due to the improvement of degree of vasodilation in the lower limb as a result of physical training.View full abstractDownload PDF (785K) -
Nobuaki SHIMIZU, Norio AKAIKE, Yutaka OOMURA, Juro MARUHASHI, Manfred ...1983 Volume 33 Issue 3 Pages 459-467
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSResponses of identified single neurons in the isolated right cerebral ganglion of Onchidium to bath applied γ-aminobutyric acid (GABA) and lioresal (LRS) were measured using conventional intracellular microelectrode techniques under current and voltage clamp conditions. In normal medium the neurons responded to both GABA and LRS. GABA induced two successive hyperpolarizations (phase I and II). Phase I was a short-lasting Cl- permeability increase while phase II was a long-lasting K+ permeability increase. LRS evoked only a long-lasting K+ permeability increase. In Ca2+-free high Mg2+ medium GABA produced only short-lasting hyperpolarization while LRS had no effect. GABA-induced phase I responses behaved as a simple Cl- electrode following changes of external Cl- concentrations. The Hill coefficient obtained from the relation between the relative change in the GABA current and the GABA concentration was almost one during the current increase phase in Ca2+-free high Mg2+ medium. These results indicate that GABA has a direct Cl- permeability increase action on the postsynaptic cell membrane of the identified Onchidium neuron while LRS has no such direct action.View full abstractDownload PDF (668K) -
Junichiro YAMAMOTO, Utako OKAMOTO, Shigeru MORITA, Kojiro KIKUI, Yoshi ...1983 Volume 33 Issue 3 Pages 469-484
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSPlasminogen, a precursor of proteolytic enzyme plasmin which lyses thrombi in vivo, is postulated to be adsorbed onto fibrin and is converted into a modified form by plasmin. The properties of the modified form examined in vitro support this hypothesis. Nevertheless, it has been postulated that no conversion of native plasminogen into the modified form occurs in plasma, since α2-plasmin inhibitor rapidly inactivates plasmin formed. However, we suggested production of the modified form in the "post-exercise" plasma. The present study was undertaken to examine production of the modified form in a simpler system, urokinase-activated plasma. The amount of the modified form in the plasma was estimated using the previous method with modification, ε-aminocaproic acid-containing polyacrylamide gel disc electrophoresis. The amount in the post-exercise plasma was also re-estimated by the present method. The amount of the modified form increased with the increase in urokinase concentration added to plasma. The presence of the modified form in the post-exercise plasma was also confirmed. The modified form could be produced in the plasma where an excess amount of α2-plasmin inhibitor was expected to exist. The present results indicate that conversion of native plasminogen into the modified form may occur in vivo, supporting the hypothesis mentioned above.View full abstractDownload PDF (1635K) -
Takuro OSA, Toshiyasu OGASAWARA1983 Volume 33 Issue 3 Pages 485-495
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSComparative effects of Mg were studied on circular muscle strips of pregnant rat myometrium near term and during delivery. Frequency and amplitude of spontaneous contraction were markedly depressed by adding 0.6mM Mg to Mg-free Krebs solution in the muscle strips taken in the morning of Days 19 and 22 of pregnancy. Frequency decreased, whereas the amplitude was not depressed by 0.6mM Mg in muscle strips taken during delivery. Plateau potential dominated in the circular muscle taken in the morning on Days 19 and 22, and it was depressed by Mg, leaving the evoked spike potential nearly unaffected. Burst of spike potentials dominated in the circular muscle during delivery, and 0.6mM Mg did not affect the burst discharge. In contrast to the variable effects of 0.6mM Mg on the polarized muscle strips of different pregnant stages, application of Mg (0.6-3.6mM) caused commonly a potentiation of tonic contraction of K-contracture generated in muscle strips of any pregnant stage. Prolonged perfusion with Mg-free Krebs solution (several hours) of the muscle strip taken in the morning on Day 22 caused a transformation of membrane activity from a plateau dominant type to a spike dominant one. With the same procedure, the depressant effect of Mg on phasic contractions was progressively decreased.View full abstractDownload PDF (861K) -
Takashi MAENO1983 Volume 33 Issue 3 Pages 497-502
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSUsing curarized frog sartorius muscles, selective presynaptic facilitatory effects of two structurally related chemicals, noradrenaline (NA) and catechol (pyrocatechol, PC), were compared by calculating the fractional release (P) from the rundown of endplate potential during a train-of-three stimulation. Below 10μM, both NA and PC increased P in a similar manner. At higher concentrations, however, the effects of NA were found to be quite different from those of PC. NA never increased further the value of P (0.11-0.13) whereas PC augmented P in a dose dependent fashion up to about 0.76. Thus, the present data suggested that NA and PC facilitate the transmitter release via different mechanisms. The effects of the latter were identical to the case of "chemical potentiation or accelerated evoked release" by 4-aminopyridine.View full abstractDownload PDF (410K) -
Shigeo MORI, Akira TAKABAYASHI, Genyo MITARAI, Shinji SAKURAI1983 Volume 33 Issue 3 Pages 503-506
Published: 1983
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSBy determining a ceiling for heart rate increase in a given exercise with increment of simulated altitude up to 7, 000m, a reduction of maximum heart rate (HRmax) in acute hypoxia was experimentally ascertained. Such a reduction was similarly observed immediately after a high-altitude expedition. In addition, the reduction rate against altitude was close to that shown previously in chronic hypoxia, indicating that the reduction of HRmax might be independent of altitude acclimatization.View full abstractDownload PDF (300K)
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