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Volume 35 (1985)
- Issue 6 Pages 875-
- Issue 5 Pages 693-
- Issue 4 Pages 535-
- Issue 3 Pages 375-
- Issue 2 Pages 179-
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Volume 35, Issue 5
Displaying 1-15 of 15 articles from this issue
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Yoshinobu KANNO1985 Volume 35 Issue 5 Pages 693-707
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn this paper, recent studies on the role of cell communication in cancer induction, particularly in two-stage carcinogenesis, were reviewed. Cell communication has been proposed to play an important role in cell growth and differentiation since its discovery. The recent finding that tumor promoters inhibit cell communication supports this possibility. The inhibition of cell communication by phorbol ester tumor promoters was also shown to correlate with enhancement of in vitro carcinogenesis in Balb/c 3T3 cells. This strongly suggests that the blocked cell communication may play a crucial causative role in the process of carcinogenesis.
Accumulated evidence indicates that phorbol ester may induce blockage of cell communication through binding to its membrane receptor which is presumably Ca2+/phospholipid-dependent kinase. cAMP enhances cell communication and protects its inhibition by phorbol ester, presumably through activating cAMP-dependent kinase. This indicates the possibility that the two kinases may be key elements for physiological regulation of cell communication. It is proposed that the disturbance of the kinase systems by endogenous and exogenous factors may be responsible for the promotion phase of cancer induction.
However, the true physiological role of cell communication in carcinogenesis remains to be demonstrated more directly. Especially, what kinds of molecules can pass through the gap junction and regulate cell functions in a cell community must be challenged in future. Some such molecules were speculatively described in this review.View full abstractDownload PDF (1316K) -
Takaaki TOYOKI, Teizo TSUCHIYA, Tsukasa TAMEYASU, Haruo SUGI1985 Volume 35 Issue 5 Pages 709-715
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSTo study the mechanism of the longitudinal stability at the level of whole muscles, paired frog sartorius muscles were attached to the opposite lever arms at unequal distances from the pivot. The lever was initially fixed in position, and when the full isometric forces were developed in both muscles, it was released to move, the result being that the advantaged muscle shortened by stretching the disadvantaged one with a nearly constant velocity depending on the ratio between their points of attachment from the pivot. The force-velocity relation of the advantaged muscle was virtually identical with the ordinary force-velocity relation obtained from the isotonic release experiments, while the force-velocity relation of the disadvantaged muscle was found to be entirely different from the ordinary one because of a marked increase in the load-bearing ability. These results are discussed in connection with the enhancement of mechanical performance in lengthening muscle.View full abstractDownload PDF (481K) -
Yoshimichi YAMAMOTO, Ken HOTTA1985 Volume 35 Issue 5 Pages 717-727
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSResponses to external Na depletion were investigated in the rat portal vein, using a microelectrode and an isometric force transducer. Mechanical response to Na depletion was characterized by a large tonic contraction with phasic contractions in a choline solution, and by phasic contractions without a tonic contraction in a Li solution. An identical depolarization of the membrane occurred in either choline or Li solution. After the tonic contraction was established in the Na-free choline-solution, the vein all but completely relaxed with partial re-admission of Na, while maintaining constant the concentration of choline. The Na-free choline-solution at 13°C did not induce the tonic contraction. In nominal Ca-free solution, no contraction occurred with a depletion of Na. A tonic contraction was also induced by Na depletion in the presence of Mn but not Ca. It is concluded that with depletion of both external and internal Na, Ca and Mn may enter the cell through channels usually occupied by Na.View full abstractDownload PDF (812K) -
Takashi NAKAHARI, Yoshiteru SEO, Masataka MURAKAMI, Hirohiko MORI, Shi ...1985 Volume 35 Issue 5 Pages 729-740
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe topical magnetic resonance (TMR) was used to study the phosphorous metabolism of a dog's submandibular gland during acetylcholine stimulation. The experiments were carried out under two conditions. One was a normal blood supply (in vivo) and the other was vascular perfusion with the artificial perfusate (in vitro). The levels of phosphorous compounds in the gland were obtained for 31P-NMR spectra of the TMR. The saliva was secreted in the both conditions, though the salivary flow under the in vivo condition was higher than in vitro. During salivary secretion, only the levels of creatine phosphate decreased under in vivo condition, while the levels of creatine phosphate and ATP decreased and the levels of inorganic phosphate increased in in vitro cases. It was concluded that the decrement of creatine phosphate during the salivary secretion indicates the acceleration of the energy metabolism in the submandibular gland.View full abstractDownload PDF (887K) -
Yutaka MATSUMURA, Shigeyuki AOKI, Mamoru FUJIMOTO1985 Volume 35 Issue 5 Pages 741-763
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSTo examine the cellular mechanism of urinary acidification in detail, micropuncture studies were performed on the in situ bullfrog proximal tubule with nigericin-based pH microelectrodes. Pencil-type double-barreled antimony microelectrodes were also used for monitoring pHs of the tubular fluids. Luminal perfusion of 10-3M cyanide caused a biphasic change in cell pH (pHi): i.e., early acidification by 0.04 pH unit in 2min and later alkalinization by 0.04. A profound depolarization of 30-35mV was observed in the peritubular membrane potential (EM Peri), although the tubular fluid pH (PHTF) was elevated by 0.11unit. Luminal substitution of 100mM Na+ by Li+ acidified the cell by 0.06 pH unit with a depolarization of EM Peri by 8mV and an alkalinization of pHTF by 0.10 unit. It is a fact that cellular acidification and luminal alkalinization are in good agreement with the depression of luminal H+ secretory mechanism. Perfusion of 10-4M SITS from the peritubular side caued a rise in pHi by 0.04 without appreciable changes in EM Peri in the short period application. Peritubular perfusion of 10-4M ouabain lowered the pHi by 0.07 with a resulting depolarization of EM Peri by 15.4mV, meanwhile, the pHTF, while initially lowered by 0.07unit, was elevated 4min later by 0.12. Inhibitions of the peritubular ion transport mechanism caused some pH changes in the same direction, both in the cell interior and the tubular fluid. Further, from the ouabain experiment, it is inferred that some linkages, mediated by Na+ and H+(or HCO3-), would exist between the peritubular and luminal membranes.View full abstractDownload PDF (1639K) -
Keiichi YOSHIMURA, Eriko NEZU, Toshie YONEYAMA1985 Volume 35 Issue 5 Pages 765-781
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIt was found that methacholine and carbamylcholine, in addition to their known inhibitory effect, augmented the effect of isoproterenol on tissue cyclic AMP accumulation. The effect of methacholine was dose dependent, and significant augmentation was obtained at 0.1 μm with the maximum being attained at about 0.5μM, whereas more than 10μM were required to obtain the inhibitory effect. Atropine completely blocked the effect of methacholine. Similar augmentation of isoproterenol effect was obtained by oxotremorine and pilocarpine. Oxotremorine, however, did not inhibit the effect of isoproterenol. Difference in the effect between methacholine or carbamylcholine and oxotremorine was observed in their binding property to cholinergic receptors. A23187 augmented the effect of isoproterenol in a dose-dependent manner. Oxotremorine and A23187 augmented the effect of isoproterenol in the presence of isobutylmethylxanthine, but they did not augment the effect of forskolin and isobutylmethylxanthine on tissue cyclic AMP accumulation. Cholinergic agonist-and A23187-induced augmentation was abolished by omission of calcium in the medium. These results suggest that the augmentation is due to activation of adenylate cyclase, which is mediated by an increase in concentration of intracellular calcium.View full abstractDownload PDF (1177K) -
Junichi SUGENOYA, Tokuo OGAWA1985 Volume 35 Issue 5 Pages 783-794
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSEach of six male subjects was exposed during rest to at least ten different thermal environments (Ta, 22-44°C; rh, 40%). Local sweat rates from both forearms were continuously recorded in a steady state of each exposure, using capacitance hygrometry. In the absence of spontaneous sweating, localized sweating was induced by intradermal administration of pilocarpine. Sweat expulsions synchronous at the two test areas were counted and their frequency (Fsw) was calculated. For each of additive and multiplicative combinations of Tcore (Tre, Tty) and Ts, the best combination for estimation of thermal input to the sudomotor center was determined using multiple regression analysis. Approximately 0.75 Tre+0.25 Ts or 0.85 Tty+0.15Ts, and (Tre-36.33) (Ts-33.13) or (Tty-36.42) (Ts-32.24) were obtained for the additive and multiplicative combinations, respectively. The correlation coefficient (r) for the relationship of Fsw to the obtained best combination, either additive or multiplicative, and that of Fsw to Tb were almost comparable to each other. It is considered that Tb can be used as an approximation of thermal input and that the characteristics of frequency of sweat expulsion is a useful index for determining whether and how much the central sudomotor mechanism is involved in the change of sweat rate in response to various thermal and non-thermal stresses.View full abstractDownload PDF (860K) -
Hiroyuki FUKUDA, Kiyoko FUKAI1985 Volume 35 Issue 5 Pages 795-801
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe nature of the afferent and efferent pathways of the recto-colonic reflex was studied electrophysiologically in the dog. A compound action potential consisting of many peaks was evoked on a sacral dorsal rootlet by a stimulus to the ipsilateral rectal strands of the pelvic nerve. Conduction velocities of the peaks indicate that Aδ and C afferent fibers innervate the colon and rectum. When the stimuli were subthreshold for C fibers, the reflex discharges of contralateral parasympathetic post-ganglionic fibers in the rectal strands and the reflex contraction of the colon were smaller than those caused by stronger stimuli. As the intensity of the stimulus to the sacral ventral roots was weakened, response peaks of preganglionic B fibers in the rectal branch, post-ganglionic C fibers in the rectal strands and a bladder branch of the pelvic nerve disappeared in the order of slow to fast conduction velocities. Contraction of the colon also decreased. The number of peaks arising from each nerve correlated well with the strength of the contraction. These results indicate that the peripheral limbs of the recto-colonic reflex arc consist of afferent Aδ and C fibers, preganglionic B fibers and post-ganglionic C fibers.View full abstractDownload PDF (565K) -
Shun-ichi KUWANA, Teijiro NATSUI1985 Volume 35 Issue 5 Pages 803-815
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effect of the elimination of input via the carotid chemoreceptor on respiratory output was examined quantitatively in anesthetized, vagotomized, and paralyzed cats. The integrated phrenic nerve activity (PNA) was recorded as an indication of output of the respiratory center. Also, the elimination of the carotid chemoreflex drive was repeatedly done by a cold block of the carotid sinus nerve at various PCO2 levels during hyperoxia, normoxia, and hypoxia. The blockade induced a reduction in PNA at each PCO2 level in every PO2 group. If the highest PNA value recorded at a high PCO2 in each PO2 condition was assigned a value of 100%, the reduction of the PNA by the blockade, i.e., the respiratory effect of the carotid chemoreflex drive, would be slightly larger during normoxia (16%) than during hyperoxia (8.7%), but would be independent of PCO2. During hypoxia, this chemoreflex effect was about 40% of a low PCO2, and decreased with increments of PCO2, finally reaching about 20% of a high PCO2 level. Furthermore, the relative contribution of the carotid chemoreceptor to respiratory output, expressed as the ratio of the PNA reduction during blockade to the PNA before blockade, was inversely proportional to both PO2 and PCO2. It is concluded that the interaction of the peripheral and central chemoreceptor drive is hypoadditive at moderate and high PCO2 levels in anesthetized cats, and this interatction is emphasized by central hypoxia.View full abstractDownload PDF (1016K) -
Jinn D. LIN1985 Volume 35 Issue 5 Pages 817-830
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSMicrovessels have been prepared from the gray matter of a rat brain by a technique involving density gradient centrifugation. A suspension of these vessels, largely capillaries, was incubated in vitro in order to investigate K transport. The flux of K (as 86Rb) into and out of endothelial cells was estimated. Potassium influx was sensitive to temperature and pH of the medium, and was markedly inhibited by 1mM ouabain (45%). Ouabain did not inhibit K efflux, as anticipated, when Na-K pumps are mainly located on the abluminal plasma membrane of the endothelial cell. The ouabain-sensitive K influx was measured at varying external concentrations of K. TheKm of ouabain-sensitive K influx was 2.95mM, which is similar to the affinity of the transport carrier of K, found in in vivo studies of K efflux from brain to the blood system. Both 1mM furosemide and 5mM barium chloride inhibited part of the ouabain-insensitive K influx. Potassium efflux was not influenced by furosemide, but was somewhat reduced by barium chloride. Noradrenalin (10-3mM) and histamine (0.1mM) did not significantly affect the influx of K.View full abstractDownload PDF (1394K) -
Adja RADJEMAN, Soo Chin LIEW, Koon Ong LIM1985 Volume 35 Issue 5 Pages 831-840
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSArtificial heart valves fashioned from bovine pericardial tissues appear to perform favourably when compared to those fashioned from other biological materials. Tissue mechanical properties have been implicated as a possible factor in determining the success or failure of the materials used for constructing tissue valve substitutes. In this study, strips of bovine pericardial tissues, cut in three different directions (along the base-apex axis of the heart, perpendicular to this axis and at an angle of 45° to this axis), were subjected to uniaxial tensile tests using an Instron machine, at strain rates of 666.7, 166.7, 66.7, and 6.7%•min-1. The pericardial tissues were found to have non-linear stress-strain curves. Anisotropy was also observed, in that the tissue was most extensible when stretched along the vertical direction and least extensible when strained along the horizontal direction. The tissues also exhibited viscoelastic properties, as the extensibility was found to decrease with the increasing strain-rate. The strain at rupture for these tissues, however, were found to be independent of the strain rates and the direction in which they were stretched. On the other hand the stress at rupture was largest when stretched in the horizontal direction and least when stretched in the vertical direction. Stresses at rupture also increase with the strain rate. The implications of the observed tissue properties, when these are used in the fashioning of tissue valve substitutes, will be discussed.View full abstractDownload PDF (675K) -
Toshiharu OBA, Ken HOTTA1985 Volume 35 Issue 5 Pages 841-851
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn single fibers of frog toe muscles placed in a Cl- free MOPS solution containing 1.8mM Ca2+, tension developed slowly in the presence of very low concentrations of Ag+. This tension was not blocked by the administration of Co2+ or Ni2+. On the other hand, two types of transient tensions developed with the application of 5μM Ag+, in fibers pretreated with 0-Ca2+ MOPS solution, containing either 2mM Co2+ or 1mM Ni2+, for 10min. In the presence of divalent cations or TTX, the first repetitive twitch-like contraction disappeared, indicating this tension is induced by action potentials repeatedly generated by the lack of divalent cations. The 2nd subsequent transient tension was caused by 5μM Ag+ in the presence of various kinds of divalent cations, or TTX. After reversion to the resting tension, the fiber was contracted by adding more than 0.1mM of Ca2+ or 25mM caffeine to the external medium. Even when placed in a Ca2+-free solution containing 3mM EGTA and 3mM Mg2+ for 30min, the fiber still developed an appreciable tension in response to 5μM Ag+. These findings suggest that a transient development of the Ag+-induced tension does not require the presence of external Ca2+. A specific sulfhydryl reagent, pCMPS, did not contract the muscle fiber. Therefore, Ag+ may develop tension by mediating unknown chemical reaction(s) other than the sulf hydryl group on T-tubular membrane proteins.View full abstractDownload PDF (862K) -
Yasuzi SAKAMOTO1985 Volume 35 Issue 5 Pages 853-866
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of Mn on electrical and mechanical activities in the circular muscle of the guinea-pig stomach were investigated. A low concentration of Mn (0.1mM) in Krebs solution caused a prolongation of the first component, resulting in an increase in frequency of the second component. However, a high concentration of Mn (more than 1mM) had a similar effect on the electrical activities in the early period, but subsequently inhibited them. The membrane was depolarized by Mn from 69 (S.D., ±6) to 63 (S.D., ±6) mV at 0.1mM and to 42 (S.D., ±5) mV at 2mM in the Krebs solution. The membrane resistance slightly decreased with 0.1mM Mn, but slightly increased with 2mM Mn. A low concentration of Mn (0.1mM) also increased resting tone and phasic contraction. These contractile responses were completely inhibited when Ca was removed from the bathing solution. The enhanced, later phasic contraction was reduced by verapamil. All these electrical and mechanical responses for Mn were not related to the nervous system. Excess Ca (15mM) inhibited the actions of Mn on the spontaneous slow waves, the resting potential, and the duration of the second component. Thus, it is concluded that Mn displaces or releases Ca from its stored sites, which are loosely-bound pools, and then induces membrane depolarization resulting in subsequent stimulation of the Ca-channel, which is blocked by a high concentration of Mn.View full abstractDownload PDF (956K) -
Hiroyuki FUKUDA, Kiyoko FUKAI1985 Volume 35 Issue 5 Pages 867-870
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSTypes of fibers in the anastomotic branches connecting the bilateral pelvic plexuses were electrophysiologically defined in dogs. The branches consist of Aδ and C afferent fibers, and parasympathetic preganglionic B and post-ganglionic C fibers.View full abstractDownload PDF (279K) -
Masaru SORIMACHI, Shigeto NISHIMURA, Kenji YANO1985 Volume 35 Issue 5 Pages 871-874
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSDihydropyridine derivative BAY K 8644 increased the rate of catecholamine secretion from the perfused cat adrenal. The magnitude of the response was inversely proportional to the extracellular concentration of Ca, i.e. the lower the Ca concentration, the larger the response. The response was markedly inhibited by Mg or nifedipine.View full abstractDownload PDF (325K)
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