Rotation drive and momentum transport with electron cyclotron heating in tokamak plasmas

The role of electron cyclotron resonance heating (ECRH) on the toroidal rotation velocity profile has been investigated in the JT-60U tokamak device by separating the effects of the change in momentum transport, the intrinsic rotation by pressure gradient, and the intrinsic rotation by ECRH. It is found that ECRH increases the toroidal momentum diffusivity and the convection velocity. It is also found that ECRH drives the codirection (co) intrinsic rotation inside the EC deposition radius and the counterdirection (ctr) intrinsic rotation outside the EC deposition radius. This ctr rotation starts from the EC deposition radius and propagates to the edge region.

Transition between internal transport barriers with different temperature-profile curvatures in JT-60U Tokamak plasmas

A spontaneous transition phenomena between two states of a plasma with an internal transport barrier (ITB) is observed in the steady-state phase of the magnetic shear in the negative magnetic shear plasma in the JT-60U tokamak. These two ITB states are characterized by different profiles of the second radial derivative of the ion temperature inside the ITB region (one has a weak concave shape and the other has a strong convex shape) and by different degrees of sharpness of the interfaces between the L mode and the ITB region, which is determined by the turbulence penetration into the ITB region.

Role of pressure gradient on intrinsic toroidal rotation in tokamak plasmas

The toroidal plasma rotation generated by the external momentum input and by the plasma itself (intrinsic rotation) has been separated through a novel momentum transport analysis in the JT-60U tokamak device. The toroidal rotation, which is not determined by the momentum transport coefficients and the external momentum input, has been observed. It is found that this intrinsic rotation is locally determined by the local pressure gradient and increases with increasing pressure gradient. This trend is almost the same for various plasmas: low and high confinement mode, co and counterrotating plasmas.

Foliar trichome- and aquaporin-aided water uptake in a drought-resistant epiphyte Tillandsia ionantha Planchon

The atmospheric epiphyte Tillandsia ionantha is capable of surviving drought stress for 6 months or more without any exogenous water supply via an as of yet to be determined mechanism. When plants were soaked in water for 3 h, leaves absorbed a remarkably large amount of water (30-40% on the basis of fresh weight), exhibiting a bimodal absorption pattern. Radiolabeled water was taken up by the leaves by capillary action of the epidermal trichomes within 1 min (phase 1) and then transported intracellularly to leaf tissues over 3 h (phase 2). The removal of epidermal trichome wings from leaves as well as rinsing leaves with water significantly lowered the extracellular accumulation of water on leaf surfaces. The intracellular transport of water was inhibited by mercuric chloride, implicating the involvement of a water channel aquaporin in second-phase water absorption. Four cDNA clones (TiPIP1a, TiPIP1b, TiPIP1c, and TiPIP2a) homologous to PIP family aquaporins were isolated from the leaves, and RT-PCR showed that soaking plants in water stimulated the expression of TiPIP2a mRNA, suggesting the reinforcement in ability to rapidly absorb a large amount of water. The expression of TiPIP2a complementary RNA in Xenopus oocytes enhanced permeability, and treatment with inhibitors suggested that the water channel activity of TiPIP2a protein was regulated by phosphorylation. Thus, the high water uptake capability of T. ionantha leaves surviving drought is attributable to a bimodal trichome- and aquaporin-aided water uptake system based on rapid physical collection of water and subsequent, sustained chemical absorption.

Current clamp at zero level in JT-60U current hole plasmas

It is found that no current is driven in a central region of a tokamak plasma once the central current density becomes nearly zero ("current hole"), in spite of high electric conductivity, at the current drive by a toroidal electric field and a radio-frequency wave in experiments on the JT-60U tokamak. This is a new, stiff, self-organized structure of a magnetic field in an axisymmetric toroidal plasma.

Reduced heat transport between edge-localized-mode bursts at low collisionality and small poloidal Larmor radius

Nondimensional parameter dependence of heat transport between edge localized modes (ELMs) is examined for H mode plasmas. The electron heat diffusivity between ELMs is reduced to the level of ion neoclassical transport in the plasma edge region which is affected by ELM burst. At lower edge collisionality, the heat flux assigned to the heat transport between ELMs is reduced and the ELM loss power is enhanced. During the inter-ELM phase, the energy confinement time becomes larger with decreasing the edge collisionality and poloidal Larmor radius.

[A case of multiple sclerosis with polyradiculitis and spinal subarachnoid block]

A case of 53-year-old female with multiple sclerosis was reported. In August 1987, she suffered from weakness in her legs and urinary retention. These signs had progressed with incomplete remissions and exacerbations. In March 1988, she developed sensory loss of all modalities below C2 level, spastic paralysis of upper extremities and flaccid paraplegia of lower extremities. Electromyography showed evidence of denervation in affected muscles of all extremities and paraspinal muscles. On lumber puncture, spinal fluid pressure fell to 0 mmH2O after removal of the spinal fluid of 12 ml, and the CSF protein was 740 mg/dl, indicating subarachnoid space block. The oligoclonal band was positive. MRI showed swelling in the cervical and upper thoracic cord, and multiple lesions in the periventricular white matter in the cerebrum. We diagnosed this case as multiple sclerosis in combination with acute polyradiculitis. The spinal subarachnoid block was considered to be caused by the swelling of the spinal cord.

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated duodenum and ileum in both guinea pigs and rabbits

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated duodenum and ileum were studied in both guinea pigs and rabbits. In the duodenum and ileum of both guinea pigs and rabbits, TM-906 (10(-6) g/ml, 10(-5) g/ml) produced a potentiation of the spontaneous contraction in preparations with low contractile activity (low tone or small contraction), while it caused an inhibition of the spontaneous contraction in preparations with high contractile activity (high tone or large contraction). The potentiation of spontaneous contraction by TM-906 was more pronounced in the ileum than in the duodenum of both guinea pigs and rabbits. When the spontaneous contraction of duodenum and ileum was decreased by atropine, the potentiation of spontaneous contraction by TM-906 was further augmented and was more pronounced in the ileum than in the duodenum. When the spontaneous contraction was remarkably potentiated by physostigmine or acetylcholine, TM-906 markedly inhibited the potentiated spontaneous contraction, and the potentiation by TM-906 seen in preparations with low contractile activity disappeared. From these results, it is concluded that TM-906 produces, depending on the contractile activity of the preparations, a potentiation or an inhibition of the spontaneous contraction of duodenum and ileum in both guinea pigs and rabbits and that the potentiation by TM-906 is more pronounced in the ileum than in the duodenum. It is suggested that the endogenous acetylcholine partly modifies the effects of TM-906, but that it does not relate to the more pronounced potentiation by TM-906 in the ileum than in the duodenum.

[Effects of trimebutine maleate (TM-906) on the gastrointestinal motility in anesthetized dogs]

Effects of trimebutine maleate (TM-906) on the spontaneous motility of the gastrointestinal tracts were investigated in anesthetized dogs by means of force transducers. TM-906, administrated intravenously or intraduodenally, produced an inhibition followed by a potentiation of the spontaneous motility in the stomach, and caused a potentiation of the spontaneous motility in the duodenum, jejunum, ileum and colon. These effects of TM-906 were observed also in the vagotomized dogs as in the intact dogs. From these results, it is suggested that TM-906 modulates the spontaneous motility of the gastrointestinal tracts primarily through the peripheral mechanism.

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder were investigated. TM-906 inhibited the contractile responses to cholinergic nerve stimulation (5 Hz) and to acetylcholine (3 X 10(-8) g/ml) to the same extent, both of which produced much the same amplitude of contraction. TM-906 noncompetitively antagonized the contractile response to methacholine, and it caused a parallel shift of dose-response curves for the contractile response to CaCl2 to higher concentrations. Moreover, TM-906 inhibited the contractile response to 50 mM KCl in a dose-dependent manner. On the other hand, TM-906 itself evoked a slight contractile response in a dose-dependent manner. The contractile response induced by TM-906 was prevented by exposure to Ca++-free solution, but not by tetrodotoxin or atropine. From these results, it was suggested that TM-906 inhibited the contractile responses to cholinergic nerve stimulation, acetylcholine, methacholine and 50 mM KCl by reducing the influx of calcium ion across the cell membrane, while it was assumed that TM-906 itself evoked a slight contractile response by increasing in some way the concentration of the intracellular free calcium ion available for the contractile systems.

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated guinea pig colon

Effects of trimebutine maleate (TM-906) on the spontaneous contraction of isolated guinea pig colon were investigated. TM-906 in the concentrations of 10(-6) g/ml and 10(-5) g/ml increased the tone without affecting the amplitude of the spontaneous contraction in the preparations with low tone, whereas it decreased the tone and the amplitude of the spontaneous contraction in the preparations with high tone. At the higher concentration (10(-4) g/ml). TM-906 decreased the tone and finally abolished the spontaneous contraction in any preparation. The increase in tone induced by TM-906 was prevented by diltiazem and exposure to Ca++-free solution, but not by tetrodotoxin, atropine, phentolamine or propranolol, and depended on the extracellular concentration of CaCl2. On the other hand, the decrease in tone and amplitude of the spontaneous contraction produced by TM-906 were not prevented by tetrodotoxin, phentolamine or propranolol. TM-906 further increased the tone increased by 10 mM KCl, while it decreased the tone increased by 30 mM KCl. From results described above, it is suggested that TM-906 possesses both a relaxing effect and an excitatory effect which seem to be due to its direct action on the smooth muscle.

[Effects of trimebutine maleate on the gastrointestinal motility in conscious dogs]

Trimebutine maleate is known to have beneficial effect in the treatment of gastrointestinal disorders. In conscious dogs with implanted force transducers, effects of trimebutine maleate on the gastrointestinal motility were investigated by intravenous injection, and the results were compared to those with metoclopramide and hyoscine-N-butylbromide. When trimebutine maleate was administered during the motor quiescence in the interdigestive state, contractions were evoked or the quiescent time was shortened in the gastrointestinal tract. In the digestive state, the gastric antral contractile activity was reduced, and duodenal activity was somehow suppressed by trimebutine maleate; but in the jejunum, ileum or colon, the activity was augmented. Injection of metoclopramide evoked a continuous contraction in the gastric antrum and duodenum during the period of motor quiescence in the interdigestive state. In the digestive state, metoclopramide caused a slight enhancement in the contractile activity of the gastric antrum. On the other hand, hyoscine-N-butyl-bromide produced no effect during the period of motor quiescence in the interdigestive state and suppressed the activity of the gastrointestinal tract during the digestive state. Thus, the pattern of action of trimebutine maleate was different from metoclopramide and hyoscine-N-butylbromide. It was concluded that trimebutine maleate produces dual actions, suppression and acceleration, on the gastrointestinal motility in conscious dogs.

[Effects of trimebutine maleate (TM-906) on the spontaneous contraction of the isolated guinea pig stomach]

Effects of trimebutine maleate (TM-906) on the spontaneous contraction were investigated in the isolated circular smooth muscle of the antrum region of the guinea pig stomach. TM-906 dose-dependently reduced the amplitude of the regular spontaneous contraction without any marked change in its frequency and basal tension. This effect of TM-906 was also observed in the presence of phentolamine, propranolol, atropine, and tetrodotoxin. However, the inhibitory effect of TM-906 was overcome by increasing the extracellular concentration of CaCl2. On the other hand, in preparations which exhibited irregular spontaneous contraction, TM-906 regularized it, and spontaneous contraction with regular frequency and amplitude was elicited. In addition, this regularizing effect of TM-906 was also observed in the presence of atropine and tetrodotoxin. It was concluded that TM-906 has dual effects on the spontaneous contraction, reducing the amplitude of regular contraction and regularizing the irregular contraction. These effects of TM-906 may be attributed to the direct action on the smooth muscle.

Effects of timepidium bromide, hyoscine-N-butylbromide and atropine on the isolated guinea pig gallbladder and sphincter of Oddi

Effects of timepidium bromide (TB), hyoscine-N-butylbromide (HB) and atropine (Atr) were studied on the isolated guinea pig gallbladder and sphincter of Oddi. In the isolated gallbladder, the contraction induced by methacholine was competitively antagonized with TB, HB and Atr: pA2 values for TB, HB and Atr were 8.44, 7.55 and 9.11, respectively. Contraction of gallbladder after field stimulation at 5 Hz was also inhibited by TB, HB and Atr as well as by tetrodotoxin (TTX). On the other hand, TB had no significant influence on the electrically evoked (30 Hz) contraction which remained after treatment with TTX. It was estimated that the inhibitory activity of TB on the contraction of gallbladder was 1/5-1/6 that of Atr and 7 times as potent as HB. In the isolated sphincter of Oddi, TB, HB and Atr reduced the perfusion pressure increased by acetylcholine (ACh), the activity of TB being 1/4 that of Atr and 3 times of HB. The contractile responses to field stimulation (5 Hz) were also inhibited by TB, HB and Atr. The inhibitory activity of TB was 1/5 that of Atr and 12 times of HB. It was also demonstrated that TB produced no significant effect on the noradrenaline (Nor)-induced contraction and isoproterenol (Iso)-induced relaxation in the gallbladder or Nor-induced increase of the perfusion pressure in the sphincter of Oddi. It is suggested that TB acts on the gallbladder and sphincter of Oddi by virtue of its anticholinergic activity.

[Bronchodilating action of (--)-1-(3, 4, 5-trimethoxybenzyl)-7-hydroxy-1, 2, 3, 4-tetrahydroisoquinoloine HCl (l-MTI) (author's transl)]

Bronchodilating action of l-MTI was investigated by intravenous administration to anesthetized animals and the results were compared to those seen with isoproterenol. Bronchoconstriction was induced by histamine or serotonin. Under pentobarbital anesthesia, the bronchodilating activity of l-MTI was approx. 1/20 that of isoproterenol in cats and dogs, but less than 1/100 that of isoproterenol in monkeys and guinea pigs. The results indicate that the bronchodilating activity of l-MTI is variable and species dependent. It was demonstrated, however, that in guinea pigs, l-MTI did not produce any bronchodilating activity, when the animals were anesthetized with urethane. The absence of the bronchodilating response in animals under this anesthesia was also seen in vagotomized, adrenalectomized and reserpinized, norepinephrine-infused guinea pigs. On the contrary, l-MTI exhibited the bronchodilating action in reserpinized, pithed or hexamethonium-treated guinea pigs anesthetized with urethane. On th other hand, isoproterenol produced a bronchodilating action in all preparations mentioned above. It was also evident that l-MTI suppressed the bronchodilating action of isoproterenol in pentobarbital anesthetized guinea pigs. In addition, l-MTI increased the heart rate of guinea pigs with a low beating rate, but decreased it when the control rate was high. These results suggest that at least in guinea pigs, l-MTI acts as a partial agonist and that the effect of l-MTI on the bronchial system depends on the sympathetic tone and/or sympathetic bronchodilator reflex, as proposed by McCULLOCH ET AL. (9).