The Japanese Journal of Physiology
Print ISSN : 0021-521X
24 巻, 5 号
選択された号の論文の6件中1~6を表示しています
  • 堀 清記, 井上 章, 飯塚 平吉郎, 山田 敏男
    1974 年 24 巻 5 号 p. 463-474
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    1. Physiological responses to heat and heat tolerance were examined in summer and winter on 39 male college students. After having been in the chamber for 30 min, sweating was induced by immersing both legs up to the kness for 90 min a water bath of 42°C in a climatic chamber maintained at 30°C with 70% relative humidity.
    2. Heat tolerance was assessed by heat strain cau ed by a certain heating condition. The heat strain was represented by a combination of relative increase in rectal temperature (B) plus relative water loss (A) and salt loss (C). Indices I and S were defined, as reported previously, as (A2+B2+C2) 1/2 and B/(A2+C2) 1/2, respectively, to assess the heat tolerance.
    3. Sweating reaction in summer was characterized by a relatively smaller salt loss despite a greater water loss, while the rise in rectal temperature was less in summer than in winter.
    4. The mean value of Index I showed no significant seasonal differences, being 0.24 in both seasons. The mean values of Index S in summer and winter were 0.81 and 1.42, respectively, the difference being statistically significant.
    5. The mean value of Index I for the athlete group, which included college sportsmen, was significantly lower than that of the non-athlete group (0.21 and 0.27, respectively, irrespective of the seasons), while no significant difference was found in Index S between the two groups.
    6. Despite the lack of seasonal variation of Index I, the magnitude of individual I showed a good correlation with heat tolerance as judged by the sweating type, n a classification system originally deve oped by Ohara.
    7. Based on these results, applicability of the indices for the assessment of individual heat tolerance is discussed.
  • 小川 徳雄
    1974 年 24 巻 5 号 p. 475-489
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    Periodic radiant heat was applied to the back of the human trunk by the use of an infrared lamp and the sweat rate of non-irradiated regions was recorded continuously by means of resistance hygrometry. A general trend was observed that the sweat rate increased as the irradiated area was warmed during the lamp-on phase and decreased with the cooling of the area during the lamp-off phase, with a delay of a few seconds. The degree of such synchronization of sweat rate withthe heating cycle was largely affected by the length of the on-off period, and varied with individuals. The individuality appeared to be most distinct with repetitive irradiation of a two-minute period, consisting of one minute each of lamp-on and lamp-off phases.
    The magnitude of the sweat response was affected by the basal level of sweat rate and by the skin region, but the pattern of the sweat response was not significantly influenced by them. No significant seasonal differences were noted in the pattern of sweat response.
    Well-synchronized sweat response was observed in a majority of natives from warm regions and in many athletes, but in few non-athletic individuals from cool districts. This type of sweat response is considered to be mediated through neural reflex pathways involving the central thermoregulatory mechanism. Improvement in sweat responsiveness may result from facilitation somewhere along these pathways, which may be acquired only by long-term heat acclimatization or adaptation to torrid climate.
  • 松尾 理, 美原 恒, 足立 千鶴子
    1974 年 24 巻 5 号 p. 491-500
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    Perforated capsules were implanted into the brain parenchyma, subcutaneous tissue, and muscle (denoted BC, SC, and MC, respectively) of dogs. After implantation, tissue grew and fluid was retained within the capsules. The effects of vasoactive drugs on the intracapsular fluid and cerebrospinal fluid (CSF) pressures were observed. Adrenalin and noradrenalin were used as pressor agents, and acetylcholine, isoproterenol, and isoxsuprine as depressor agents, together with certain other drugs. The following results were obtained:
    1. The observed changes in CSF and intracapsular fluid pressures were largely dependent on the induced blood pressure changes following drug administration.
    2. The CSF pressure was increased by both the pressor agents and depressor agents.
    3. The SC and MC pressures were decreased by the pressor agents and generally increased by the depressor agents.
    4. BC pressure was increased by the pressor agents and decreased mostly by isoproterenol, affected rather variably by isoxsuprine, while there was an initial decrease and subsequent increase with acetylcholine.
    5. The pattern of these pressure responses in the BC fluid was clearly different from that in the CSF. The direction of pressure fluctuation in BC was opposite to that in both SC and MC.
    6. Possible mechanisms for these capsular and CSF pressure fluctuations are discussed.
  • 簑田 昇一
    1974 年 24 巻 5 号 p. 501-512
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    1. Tetraethylammonium (TEA) augmented the amplitude of the later phase of the post-tetanic hyperpolarization (PTH) in bullfrog sympathetic ganglion cells. The present report deals with the mechanism underlying the later phase (the late slow component) of PTH.
    2. The late slow component persisted in the presence of ouabain, suggesting that it was not associated with the activation of the Na pump.
    3. The membrane conductance was increased during the development of the late slow component. The polarity of the late slow component was reversed when the conditioning hyperpolarization exceeded the potassium equilibrium potential.
    4. The amplitude of the late slow component was increased in the potassium-free solution and decreased in the potassium-rich solution, and was not affected by replacing external chloride ions with methylsulfate ions.
    5. The late slow component was abolished in the low-calcium solution or in the solution containing manganese ions, whereas it was augmented in the calcium-rich solution.
    6. These results suggest that the late slow component is produced by an increase in potassium conductance of the cell membrane, which is caused by an increase in the calcium influx during the generation of action potentials.
  • 酒井 敏夫, 栗原 敏, 吉岡 利忠
    1974 年 24 巻 5 号 p. 513-530
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    1. The action of manganese ions on excitation-contraction coupling in frog skeletal muscle fibres was studied.
    2. In normal Ringer's solution, twitch tension development was inhibited by the addition of 10 mM-Mn. The inhibitory effect of Mn on twitch tension development was not eliminated by addition of 1 mM caffeine.
    3. In 10 mM-Mn Ringer's solution, membrane potential of the semitendinosus muscle fibre was increased by 9.1 mV and the hyperpolarizing action of Mn was observed in various concentrations of potassium up to 50 mM.
    4. The action potential was still observed in 10 mM-Mn Ringer's solution and negative afterpotential was prolonged. In 10 mM-Mn Ringer's solution, an intensity of electrical current needed to elicit action potential was increased.
    5. Negative afterpotential which disappeared after glycerol treatment (HOWELL and JENDEN, 1967) could not be regained by treatment of 10 mM-Mn.
    6. Mn suppressed potassium contractures induced by 80 mM-K or less (constant [K]×[Cl] product). Removal of Mn from 50 mM-K Ringer's solution produced an unusual tension development. Tension development produced by Mn removal from 80 mM-K, 10 mM-Mn Ringer's solution was smaller than that produced by Mn removal from 50 mM-K, 10 mM-Mn Ringer's solution.
    7. Caffeine rapid cooling contracture was not affected in the presence of Mn. After the disruption of T-tubules produced by glycerol treatment, caffeine rapid cooling contracture was also observed even in the presence of Mn.
    8. No morphological changes in muscle fibres treated with Mn were recognized by electron microscopical studies.
    9. From these results it was considered that Mn acted on transverse tubules to inhibit the influx of Ca, but did not directly affect the sarcoplasmic reticulum.
  • 木元 良子, 斎藤 雅彦, 後藤 昌義
    1974 年 24 巻 5 号 p. 531-542
    発行日: 1974年
    公開日: 2011/06/07
    ジャーナル フリー
    1. Effects of caffeine on the action potentials, membrane currents and contractile responses of the bullfrog atrial muscle were investigated by means of the double glycerol-gap technique.
    2. Caffeine, 3, 10, and 50 mM in concentration, caused a potentiation of twitch contraction without producing contracture. The potentiation was larger the higher the concentration. The duration of action potential as well as the relaxation time of contraction was prolonged.
    3. Under voltage clamped conditions and constant presence of tetrodotoxin (2.5×10-7g/ml), 5 mM caffeine produced an augmentation and a rapid onset of the active slow inward current, as well as contractile tension, and decreased the membrane cord resistance.
    4. The curve of the voltage-tension relationship was shifted to the left and upward by 5 mM caffeine. Maximum augmentation of tension appeared for depolarizing pulses of 60-80 mV.
    5. In a preparation pretreated with 4-fold Ca Ringer solution, 10 mM caffeine induced a contracture which was not abolished by 1 mM La+++.
    6. In the presence of 1 mM La+++, 10 mM caffeine produced an augmentation of twitch contraction and a transient contracture. Caffeine also augmented a sodium-free contracture under the presence of La+++.
    7. These results are interpreted as indicating that:
    a) Caffeine acts on both the surface membrane and the sarcoplasmic reticulum. b) It enhances the inward calcium current augmenting the contraction directly and indirectly through the sarcoplasmic reticulum. c) In normal Ringer solution, the amount of the accumulated calcium is very small but is increased by pretreatment in calcium-rich solution. d) La+++ inhibits both the inward and outward transmembrane calcium movements.
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