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Volume 39, Issue 1
Displaying 1-16 of 16 articles from this issue
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Hiroshi ASANUMA, Robert MACKEL1989 Volume 39 Issue 1 Pages 1-19
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSDownload PDF (1576K) -
Yoshinobu OHIRA1989 Volume 39 Issue 1 Pages 21-31
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSEffects of denervation and deafferentation on mass and enzyme activity of soleus and plantaris muscles were studied when the synergistic gastrocnemius was either intact or tenotomized in adult male Wistar rats. Denervation of the sciatic nerve at L4 and L5 induced a severe atrophy (approximately 50%) in both soleus and plantaris within 2 weeks. Deafferentation at L4 and L5 also caused a decrease in muscle weight for soleus and plantaris (approximately 11 and 24%, respectively). No compensatory response to the tenotomy was induced either for muscle weight or enzyme activity in both denervated and deafferentated muscles. It is suggested that the efferent information(s) through the nerve fibers has an important effect of the regulation of both muscle mass and enzyme activity. Its effect on the activities was greater in mitochondrial than cytoplasmic enzymes. The data also suggest that the afferent information(s) plays a significant role for the regulation of muscle mass, including an induction of compensatory hypertrophy, but not for enzyme activity.View full abstractDownload PDF (824K) -
Yuji AMAGAI, Shiro KASAI1989 Volume 39 Issue 1 Pages 33-42
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSUnder a high-Ca condition (>5mM), myotubes of a mouse myogenic cell line MC3T3-A1/M13 generated a long-lasting Ca action potential and a prolonged afterhyperpolarization (a. h. p.) during their in vitro development. The action potential was sensitive to Co or verapamil. Under a voltage-clamp condition, membrane depolarization more positive than -20mV evoked a Ca-dependent inward current, which was apparently prolonged and responsible for the generation of the long-lasting action potential. The appearance of the Ca action potential preceded that of a Na spike by about 24h, and it developed so that the maximum rate of rise became 26±4V/s by day 7. Then this Ca-dependent potential faded as the myotubes matured, until the action potentials became solely Na-dependent. The a. h. p. was evoked accompanying the Ca action potential and was inhibited by quinine or quinidine, showing that it is operated by Ca-activated K channels. This channel developed together with the Ca channel and continued to exist during the myotube maturation process. These results indicate that the MC3T3-A1/M13 myotube at the initial stage of development has a highly developed Ca spike system that is due mostly to a high-threshold-type Ca channel.View full abstractDownload PDF (745K) -
Haruo TANAKA, Yusuke IMAI1989 Volume 39 Issue 1 Pages 43-50
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe short-circuit current (Isc) across the frog skin in the steady state reflects the active Na+ transport. Inhibition of the Na+-K+ pump by ouabain causes slow decay of Isc. It has been suggested that this slow ouabain effect on Isc could be due to the asymmetric ionic permeations of frog skin. That is, Na+ flux at the apical membrane and K+ flux at the basolateral membrane transiently generate the transepithelial cationic fluxes and are measured as the Isc even under the condition of active Na+ transport arrest. However, this hypothesis on the transient Isc has not been studied experimentally. In the present study, transient inward and outward Isc were observed alternately even after pump arrest by changing the ionic compositions of the bathing solutions in a Ussing's chamber. The time constant of Isc decay was 20-30min. The Isc responses were quicker and stronger on the isolated epithelia than on the whole skin. Both Isc responses were blocked by amiloride, a Na+ channel blocker. Measurements of the ionic composition of isolated epithelia under experimental conditions indicate that the passive Na+ flux across the apical membrane and the passive K+ flux across the basolateral membrane cause both transient inward and outward Isc under the ouabain-treated condition of frog skin.View full abstractDownload PDF (530K) -
Guifa CHEN, Hikaru SUZUKI1989 Volume 39 Issue 1 Pages 51-65
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of ACh and histamine on electrical and mechanical properties of intrapulmonary artery and vein muscles were studied in rats. In the artery, ACh and histamine indirectly relaxed the precontracted muscles in high-[K]o solution via the release of endothelium-derived relaxing factor (EDRF) from the endothelial cells, and also produced contractions by acting directly to the muscles. ACh and histamine elicited a transient hyperpolarization of the arterial smooth muscle membrane mainly due to an increase in K permeability, only in the presence of endothelial cells. In the absence of endothelial cells, histamine and ACh depolarized the arterial smooth muscles. The intrapulmonary vein consisted of the invaded cardiac muscles; and ACh, but not histamine, hyperpolarized the membrane of these muscles by an increase in K permeability, with no relationship to the endothelial cells. It is concluded that in the rat intrapulmonary artery, ACh and histamine elicit excitatory and inhibitory responses in hese vascular muscles in direct and indirect manners. The indirect actions involve relaxing and hyperpolarizing factors released from the arterial endothelial cells. ACh but not histamine elicited inhibitory responses to the intrapulmonary vein muscles in a direct manner.View full abstractDownload PDF (999K) -
Poul-Erik PAULEV, Jens E. THORBØLL, Ulla NIELSEN, Peter KRUSE, ...1989 Volume 39 Issue 1 Pages 67-74
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe purpose of this study was to evaluate the role of endogenous opiates in modulating physical performance during dynamic exercise in conscious man. The plasma concentration of β-endorphin (BEP) and of adrenocorticotropic hormone (ACTH) along with muscle pain (McGuill Pain Questionnaire) were assessed in 17 trained, male runners before and after running the longest possible distance within 12min (i.e., the Cooper test). Each runner participated twice in the test (double-blind cross-over design), with a 1-week interval-with or withoutan injection of the opiate antagonist naloxone (0.8mg i. v.). The average (SEM) distance reached was 3, 198 (45)m in the naloxone test and 3, 240 (38) m in the placebo test. The BEP increased significantly during the tests by a factor of 4.1 on naloxone and by 2.8 on placebo (from the normal resting averages of 1.7 and 2.1pmol/l, respectively). The ACTH also increased significantly by a factor of 2.0 on naloxone and 2.5 on placebo (from the normal resting averages of 19.3 and 16.8pmol/l, respectively). There were no significant differences between the naloxone and the placebo test with respect to the increments of BEP or ACTH by exercise. However, the perception of muscle pain was enhanced with naloxone. The increased perception of pain did not decrease the athletes ability to perform in terms of the distance run. We conclude that endogenous opiates are involved in the perception of pain associated with exhaustive exercise and may subserve psychological rather than physiological functions during exercise.View full abstractDownload PDF (599K) -
Yoriko TAKIKAWA1989 Volume 39 Issue 1 Pages 75-85
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of Cs ions on the frequency of miniature end-plate potentials (MEPPs) were. investigated at the frog neuromuscular junction. The frequency of MEPPs increased gradually with time, after a delay, when part of the NaCl in normal Ringer's solution was replaced isotonically with CsCl. The delay was greatly prolonged and the rate of increase in MEPP frequency slowed when a low concentration-between 6 and 40mM-of CsCl was applied. As the external concentration of CaCl2 (0.4-6.3mM) was increased, the delay was prolonged and the rate of increase became slower. The effect of Mg ions was qualitatively the same as that of Ca ions. In the case of reapplication, Cs ions produced a prompt increase in MEPP frequency and the rate was much faster than before. When the solution contained no added Ca and 1mM EGTA, no appreciable change in MEPP frequency was observed when CsCl was applied. It is suggested that the first step in the gradual increase in MEPP frequency is the slow entry of Cs ions into the nerve terminal, following which transmitter release is mainly induced by the influx of external Ca ions.View full abstractDownload PDF (783K) -
Hiroko TOYOTA, Moto MATSUMURA1989 Volume 39 Issue 1 Pages 87-100
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSMembrane potential and contraction were investigated in cultured chick embryonic heart cell aggregate. The cells were stimulated through the intracellular microelectrode, and the contraction of the cell aggregate was measured from the shortening of the diameter. The contraction decreased if the stimulation frequency was raised in the range between 20/min and 100/min; namely, the negative relationship between contraction strength and stimulation frequency. The peak action potential or plateau duration was not affected by the change in the stimulation frequencies unless they exceeded 60/min, but they were shortened at frequencies higher than 75/min. In the latter case, the decrease of contration strength was related to the shortening of plateau duration. If the stimulation frequency was lowered suddenly, the following contraction was transiently increased without any noticeable change in the shape of the action potential. When TTX was added (3-10×10-6M), the rate of the spontaneous activity was reduced, which made it possible to study the contraction strength at low stimulation frequencies. In TTX medium, similar to the observations in the control medium, the relationship between contraction strength and stimulation frequency was also negative. In the medium containing TTX plus verapamil (5-9×10-7M), the peak action potential was inhibited during the repetitive stimulation dependently on the stimulation frequency, accompanied by the concomitant decrease of contraction strength. These results suggest that the negative inotropic effect of the stimulation frequency is caused in part by the change in Ca2+ inflow.View full abstractDownload PDF (1029K) -
Hiroko TOYOTA, Moto MATSUMURA1989 Volume 39 Issue 1 Pages 101-114
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe rate of the spontaneous activity of cultured cells from the chick embryonic ventricle was only slightly increased by norepinephrine (NE) or epinephrine (EP), even if it was applied close to the cell. On the other hand, the amplitude of contraction, measured from the shortening of the diameter of the cell aggregate, was clearly augmented by up to 50%. Intracellularly injected cAMP also potentiated contraction. Namely, NE, EP, or CAMP showed positive inotropic action but slight Chronotropic action on cultured ventricle cells. NE produced an increase in the action potential amplitude, shortening of action potential, and slight hyperpolarization in 17- to 19-day-old but not in 7- to 9-day-old embryo. If NE was applied to the cells whose plateau potential was inhibited by the previous treatment with nifedipine, NE recovered the plateau level to the control. Iontophoretically injected cAMP also recovered the plateau level once it had been inhibited by nifedipine or verapamil. In some cells, the membrane was transiently depolarized after the end of injection and turned back to the control level. This transient depolarization took place spontaneously again. It was suggested that the Ca2+-induced Ca2+ release mechanism from the sarcoplasmic reticulum was involved in the cyclic depolarization.View full abstractDownload PDF (1087K) -
Seishi HAKOZAKI, Mitsuhiko MATSUMOTO, Kazuhiko SASAKI1989 Volume 39 Issue 1 Pages 115-130
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSRaising the temperature from 22 to 32°C induced a marked hyperpolarization (15-30mV) associated with an increase in membrane conductance of Aplysia neurons, whereas lowering the temperature from 22 to 12°C caused a significant depolarization (10-20mV) with a decrease in conductance. These temperature effects were far greater than those expected from the Nernst equation. The reversal potentials of these temperature responses corresponded with the equilibrium potential of K+, suggesting these responses were produced by opening or closing of K+ channels. Ouabain (5×10-4M) did not affect these temperature responses though it depolarized all cells examined (5-25mV). Intracellularly injected guanosine 5′-O-(2-thiodiphosphate) (GDPβS) selectively depressed the response to warming without affecting the response to cooling. Intracellular application of guanosine 5′-O-(3-thiotriphosphate) (GTPγS) produced a gradual increase in K+ conductance of the resting membrane and apparently depressed the response to warming while it markedly augmented the response to cooling. These results suggest that GTP-binding protein can be activated thermally to open K+ channels without receptor stimulation. It is significant that the resting membrane potential of the neuron in the central nervous system may be regulated not only by Na+ pump but also by spontaneous activation of a certain GTP-binding protein, at least in Aplysia.View full abstractDownload PDF (1056K) -
Pratima PAL, Juthika KOLEY, Somnath BHATTACHARYYA, Jyoti Sen GUPTA, Bi ...1989 Volume 39 Issue 1 Pages 131-144
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn total, 86 units were recorded from T2 and T3 left thoracic rami of cat. These receptors were located on the circumflex coronary artery, anterior descending coronary artery, and its adjacent myocardial ragions. The conduction velocity of these fibres was in the range of "C" (0.5 to 1.8m/s) and "A δ" (5.96 to 17m/s) fibres. Out of these 86 units, only 28 units were activated by coronary occlusion. The average resting frequency of the spontaneous unit was 0.8±0.06impulses/s which increased to 35±4.8impulses/s on mechanical probing. In order to examine whether the units sensitive to coronary occlusion were also responsive to algesic agents, some of these units were studied applying lactic acid, bradykinin, prostaglandins, and nicotine. It was observed that these ischemia-sensitive units are also sensitive to lactic acid (10 units), bradykinin (16 units), prostaglandins (12 units), and nicotine (15 units). These ischemia-sensitive units are presumably nociceptors and activated by algestic agents that cause cardiac ischemic pain.View full abstractDownload PDF (973K) -
Biswanath KOLEY, Pratima PAL, Juthika KOLEY1989 Volume 39 Issue 1 Pages 145-153
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSA total of 25 afferent units were recorded in the thoracic sympathetic rami (T3-T4) localised at the base of the bracheocephalic trunk and the descending aorta. Two types of receptors, Type I and Type II, were found. Type I receptors, localised at the base of the bra-cheocaphalic trunk, were fast adapting and exhibited synchronous discharge with each systolic height of blood pressure and behaved like baroreceptors. There was no discharge at the diastolic phase of the cardiac cycle. These receptors also gave occasional single spike at each systolic height of pressure of about 90-120mmHg. When the systemic pressure was increased from 120 to 180mmHg due to occlusion of the descending aorta or intravenous administration of adrenaline, the frequency of discharge of Type I receptors increased and they behaved like the typical sino-aortic baroreceptors. Type II receptors, localised over the wall of the descending aorta, fired irregularly and they did not have any relation with heart beat and did not behave like baroreceptors. On the basis of the present observation it may be suggested that Type I receptors are high threshold baroreceptors which play a role in the homeostatic control during high blood pressure and that Type II receptors do not play such a role.View full abstractDownload PDF (581K) -
Kazuo YOSHIZAKI, Yoshiaki TAKANASHI, Takao MOTONAGA, Shod NARUSE, Hiro ...1989 Volume 39 Issue 1 Pages 155-167
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe activity of electroencephalogram (EEG) and cortical somatosensory evoked potential (SEP) was suppressed during cerebral Ischemia in rats subjected to the 4-vessel occlusion. Considerable variations were demonstrated in the decrease of phosphocreatine and ATP concentration during ischemia among the rats measured with 31P-NMR, accompanied with cerebral acidification. Hypercapnia, induced in the rats studied by the inhalation of a gas mixture of 3O-4O% CO2, suppressed the activity of EEG and cortical SEP. The cerebral acidification observed during the ischemia was more severe than that under the hypercapnia, implying that cerebral acidification is one of the possible causes for the decrease in the electrical activity of the brain during ischemia.View full abstractDownload PDF (903K) -
Ippei HATAKEYAMA, Zyn'ichi SIMADA1989 Volume 39 Issue 1 Pages 169-181
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSElectrocapacitography devised for medical purposes by Hatakeyama was applied as a noninvasive volumetric method to investigate circulation in the rabbit head and brain. The effective electric capacitance was measured by means of a highly sensitive device. An electrocapacitogram (ECPG) of the head, considered to reflect the volume of intracranial as well as extracranial blood vessels, varied rhythmically with cardiac beat and respiratory movement. In general, the pulsatile variations of ECPG in synchronization with cardiac beat (ECPG pulse) bore a resemblance to arterial pulse. Occlusion of the common carotid artery caused the ECPG level corresponding to mean vascular volume to fall markedly and in most cases the amplitude of ECPG pulse was diminished. By rapid infusion of 5ml of the blood into intracranial blood vessels via the internal carotid artery or into extracranial blood vessels via the external carotid artery, ECPG level was raised transitorily, the effect of extracranial infusion being larger than that of intracranial infusion. Stimulation of the central cut end of the cervical sympathetic nerve reduced ECPG level considerably. This response was greatly diminished by carotid occlusion and sometimes a temporary rise of ECPG was observed at the beginning of the stimulation. In several cases the effect was reversed completely by carotid occlusion and an increase of ECPG during the stimulation was observed. These findings suggest the existence of a sympathetic vasoconstrictor in the head as well as a sympathetic vasodilator of the brain, although in confirmation of this review further investigation is required. ECPG of the head is demonstrated to be a useful method for investigating circulation in the head including brain.View full abstractDownload PDF (878K) -
Jin-Hong FAN, Susumu TERAKAWA1989 Volume 39 Issue 1 Pages 183-189
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe turbidity of the mouse adrenal medulla was measured using a photodiode and a video system equipped with an image processor. Acetylcholine applied at concentrations of 30 to 100μM induced a slow decrease in turbidity by about 0.1% of the resting value. This response was suppressed by Cd-containing or Ca-deficient medium. These results and a video image suggested a structural change in the chromaffin cells associated with the secretory activity.View full abstractDownload PDF (717K) -
Tsukasa TAMEYASU1989 Volume 39 Issue 1 Pages 191-197
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe author attempted to deduce a possible cross-bridge (XB) distribution as a function of x, the amount of stretch of the XB, by applying the Huxley-Simmons theory with their recent experimental data to a steady isometric contraction. I found no XB distribution which satisfied at once the Huxley-Simmons theory, their data and observations in muscle energetics and biochemistry. Further, a computation with a simple model suggested that the XB distribution could be broadened by the elasticity of the thick and/or the thin filament if it existed.View full abstractDownload PDF (431K)
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