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雑誌文献

生体の科学11巻6号

1960年12月発行

雑誌目次

Symposium On Active Transport

In Opening the Symposium

著者:

ページ範囲:P.263 - P.263

 It is our greatest pleasure to have a symposium on active transport with the attendance of Dr. Visscher.This is the first international meeting on active transport to be held in Japan.
 Dr. Visscher is really a pioneer in this field.He has published many papers on intestinal absorption of salts and water since 1935.His outstanding work, using radio isotopes, has clarified for the first time the relation between influx and outflux of salt through the intestinal wall.

A General Remark

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ページ範囲:P.264 - P.264

 Professor Yoshimura and Yas Kuno! It is very great honor for me to have so many of you come not only from this city, but from cities far away to participate in this symposium on active transport.
 As Professor Yoshimura has said, this is the subject in which I have been interested for many years. I would say at the outset, however, that many of you here are doing the important work in this field at the present time and that my own most active contribution has been sometime in the past.

Physiological Problems Concerning Water Flux—A Lecture of Travelling Mission of International Union of Physiological Sciences

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ページ範囲:P.265 - P.266

 There are at least six known mechanisms for water flux across biological membranes.
 1.Thermal agitation(diffusion)
 2.Solvent drag in ion movement in an electrical field(limiting case:electro-smosis)
 3.Carriers(hydrated solutes)
 4.Gravity
 5.Pressure
 6.Pinocytosis(vacuole movement)
 Another theoretically possible mechanism is thermosmosis.

Incorporation of 32P into Phosphate Esters in Human Erythrocyte during Very Short Time Intervals

著者:

ページ範囲:P.267 - P.270

 As an attempt to elucidate the mechanism of phosphate uptake by human erythrocyte 32P incorporation into acid-soluble organic phosphates during very short time periods of incubation with 32P-orthophosphate was pursued by the use of ion exchange resin chromatography for the separation of the phosphorus compounds.Then seconds after addition of 32P to the blood sample,only ATP and ADP were shown to be labelled with 32P to a detectable extent, while the other substances, such as sugar phosphates and phosphoglycerates were not.The same results were obtained by incubation of the blood with 32P for short time intervals of not more than 90 seconds.After 30 minutes,32P was incorporated into sugar phosphates and phosphoglycerates.The results revealed that the incorporation of 32P into 2, 3-diphosphoglycerate was a rather sluggish one.
 To obtain further information about the reaction sequence involved in the uptake of inorganic phosphate into organic phosphates inside the cells, the time course of 32P-incorporation into ATP was determined.The radioactivity increased linearly with time.There appeared a short but distinct time lag before the increase strated.This suggests that a certain intermediary step may exist between inorganic orthophosphate in plasma and ATP in the cell.It is likely that the entry of phosphate involves phosphorylation during phosphoglyceraldehyde oxidation to 1, 3-diphosphoglycerate, localized at the cell surface.Unfortunately, the ester is extremely unstable so that separation and assay of this compound were impossible.There appeared highly radioactive unidentified phosphate compounds other than ATP and ADP,at the end of 10 seconds of incubation but none of them coincided with 1, 3-diphosphoglycerate.Furthermore, these compounds were often demonstrated in zerotime controls.Consequently too much biological significance should not be placed upon the presence of these compounds with radioactivity in very early periods of incubation.

Effects of Metabolic Inhibitors and Ouabain on Transport of Ions through Frog Skin

著者: ,   ,  

ページ範囲:P.271 - P.275

 It might reasonably be expected that various metabolic inhibitors inhibit active transport of matter, a process which requires energy derived from cellular metabolism.However, Schatzmann13) showed several years ago that certain cardiac glycosides and aglycones inhibited selectively the active transport of Na and K in human red cells.Since then these drugs have been studied considerably with respect to the inhibitory action on active transport in several living membranes.
 Since the work of Ussing and Zerahn15), the active Na transport across the frog skin has been studied extensively because with this material it is relatively easy to obtain various information about the active transport of ions.

Electrophysiological Activities of Nerve Fiber and Chemical Properties of its Membrane

著者:

ページ範囲:P.276 - P.280

 When the voltage clamp technique was applied to a single Ranvier node of a toad,the so-called Na-current is obtained due to the excitation of the membrane.The Na-current has been explained by the Na-theory as an increase in Na-permeability of the nodal membrane during activity.
 Experimental setups for recording the action potential and the action current, and for the voltage clamp experiment of a singleRanvier node of a toad are shown in Fig. 1.

Active Transport of Amino-acid Across the Brain Cell Membrane

著者: ,   ,  

ページ範囲:P.281 - P.287

 When brain cortex slices were incubated aerobically in a saline medium in the presence of glucose as a substrate, amino-acids such as γ-aminobutyric acid(GABA),β-alanine,aspartic acid or D-,L-glutamic acid added were accumulated in the slices actively from the medium.If glutamate, an acidic amino-acid, was present in the medium in the concentration of 5 mM, the contents of intra-cellular water and potassium ions were increased markedly accompanied by the accumulation of glutamate.To the contrary,when GABA, a neutral amino-acid, was accumulated in the slices, there was very little change in the intracellular water and potassium content on a dry weight basis calculated by the chloride assumption.The evidence has been confirmed by electon-microscopic examination which indicated swelling of the nerve cells in the brain cortex.
 In potassium free medium, amino-acid transport was suppressed almost completely.However, GABA transport in the slices was augmented on omitting calcium ions from the medium or upon pyridoxal addition.The carrier system of GABA transportation across the cell membrane has been studied in relation to P32 turnover of phospholipid fractions in brain tissue.The incorporation of P32 into the phospholipids, particularly phosphatidic acid and phosphatidyl choline in the cytoplasmic particulates of brain tissue which are thought to be main structural elements of the nerve cell membrane, was greatly increased during the accumulation of GABA in the slices.This phenomenon has also been observed in a potassium rich medium which stimulated the metabolism of brain slices.Thus these phospholipids in cytoplasmic particulates might play an important part as carriers in the active transport across the brain cell membrane.

Mechanism of Salt Secretion through Salivary Gland

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ページ範囲:P.288 - P.295

 1) Much experimental evidence is presented to show that the precursor solution is produced in the gland acinus and, because Na, Cl and HCO3 are reabsorbed from the solution in the striated part along the duct, the final saliva is secreted in the form of a hypotonic solution. The pH of saliva is governed by bicarbonate concentration and is a little alkaline. The bicarbonate is secretednot only from gland acini but is also supplemented by the striated part under activity of carbonic anhydrase. Since the sublingual gland has only a rudimentary striated part, sublingual saliva is isotonic and is nearly neutral.
 2) It is ascertainted that a salivogram of submaxillary gland of dog is composed of positive and negative potentials. Postulation is made that the negative potential originates from gland acini and the positive one from the striated part. Both component potentials seem to be ruled predominately by active transport of anions especially of Cl.
 3) It is verified with perfused salivary gland that energy rich phosphate of ATP is involved in energy consumption insalivary secretion. Energy liberated by glycolysis and oxidation may be utilized for restoration of secretory energy.
 4) Concentrations salts in saliva are not only controlled directly by theire respective concentrations in serum but also by nervous functions which reflect changes in osmotic pressure in systemic blood to salivary compositions. Mineral corticoid can exert some influences upon salivary composition. It follows that salt excretion in relation to water excretion from salivary gland is controlled by the direct influence of serm composition, nervous activties and hormonal functions.

Biochemical and Electrophysiological Aspects of Gastric Acid Secretion

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ページ範囲:P.297 - P.304

 1.The H ion secretion, O2 intake and lactic acid production of the toad mucosa under the influence of metabolic inhibits were measured, and some relations among the Hion secretion, O2 intake and lactic acid production have been discussed.
 2.The H ion secretion and O2 intake of toad mucosa were measured under various concentrations of ethyl-urethane.The H ion secretion was strongly inhibited by 3% ethyl-urethane, while the O2 intake was only slightly inhibited.
 3.Generally, pentabarbital-Na inhibited the H ion secretion and O2 intake, but at concentrations less than 1mM the H ion secretion and O2 intake were promoted.These promoting effects were disturbed by Ringer solution containing K ion of 60mM.
 4.The P. D. and d. c. resistance of mucosa during the lag period of H ion secretion were found.The P. D. and the resistance of mucosa reached a steady value when the H ion secretion began to take place.
 5.The relations between the P. D. and the NaNO3 concentration were observed.They indicated a straight line relationship.
 6.The H ions produced under an aerobic condition were drawn out from the mucosa under aerobic conditions of more than 15 minutes could be drawn out.The rise or fall in the P. D. had an influence on drawing of H ion, but when the mucosa was under the anaerobic condition from the beginning, the P. D. showed no influence on the H ion secretion.Based on foregoing facts, a driving mechanism is suggested for the acid secretion:the H ion is produced by aerobic metabolism and transportation of H or XH is performed by an electrical energy.

Electronmicroscopic Studies of Active Transport; Protein Reabsorption in Tubular Cells

著者: ,  

ページ範囲:P.305 - P.310

 It is well known that proximal tubular cells reabsorb not only water, glucose and electrolytes, but also large molecular substances such as protein and lipoprotein.
 The mechanism of protein reabsorption in the proximal tubular cells has been described by many investigators as a process in which the protein included in the tubular fluid is reabsorbed into the cytoplasm by active movement of cell membrane(so called pinocytosis and athrocytosis)and then concentrated within the mitochondria or "droplets".

Analysis of Reaction Kinetics of Some Diuretics

著者: ,   ,  

ページ範囲:P.311 - P.316

 1.The reaction mechanism of newer synthesized sulfonamide derivative benzothiadiazines, was investigated in human subjects.They were acetazolamide, chlorothiazide,hydrochlorothiazide, hydroflumethiazide, and benzydroflumethiazide.
 2.Results obtained from the preliminary experiments with short term and long term administration of diuretics suggested that the carbonic anhydrase inhibition may not be the specific action mechanism of these diuretics and may be only an attendant effect.
 a)In the short term experiments, the increment of sodium excretion caused by each diuretic was of the same order of magnitude but that of anions reflected the carbonic anhydrase inhibiting activity of each diuretic.
 b)In the long term experiments, the changes of serum electrolytes concentration following the long term administration of each diuretic reflected the carbonic anhydrase inhibiting activity.
 c)In certain cases of the short term experiments, the inhibited fractions of transport mass of electrolytes were calculated.The inhibited fraction of sodium transport,i.e.,�Na, invariably exceeded that of hydrogen, i. e.,�H.It was seen not only in the cases of the benzothiadiazines but also in that of acetazolamide.
 3.Reaction kinetics of the diuretic effect of these diuretics were analyzed from the relation between the excreted amount of the diuretic and that of the electrolytes.In this experiment, urinary excretions of the diuretic compound and electrolytes were determined simultaneously following the intravenous administration of each diuretic to a fasted normal adult.The relation between the urinary excretion rate of diuretics and that of electrolytes resembled to the one seen between substrate concentration and reaction velocity in any enzymic reaction.Therefore, it is suggested that the mode of diuretic action may be a first order reaction between the diuretic agent and the supposed electrolyte carrier system.
 4.In the kinetic experiment, the diminution of diuretic effect was observed when the excretion of diuretic agent exceeded a certain limit.This phenomenon may be explained by assuming that the renal tubular transport of sodium is the difference between the ion movement in the direction of capillary to tubular lumen and that of the opposite direction.
 5.The clinical applications of the dose response curve obtained from the kinetic analysis were discussed.
 6.The significance of the diuretic agent as the specific inhibitor of the electrolyte transport system of the studies on active transport mechanism of electrolyte was discussed.

Transport of Calcium and Inorganic Phosphate across the Intestinal Wall of the Rat

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ページ範囲:P.317 - P.320

 The mode of transport of calcium and inorganic phosphate was investigated in the everted sac of rat intestine.
1)The absorptive capacity for both calcium and phosphate is greatest at the jejunum and decreases at lower parts of intestine.
2)In jejunum and ileum, calcium is transported actively from the mucosal side to the serosal side, but its relative magnitude in the total influx is not large.
3)The phosphate transport is apparenly explained in terms of electrochemical gradient, but the mechanism of transport is not simple free diffusion, because by the change of the potential difference the flux ratio becomes different from that calculated under the assumption of simple free diffusion.
4)At low temperature the net water flux increases but the influx of calcium and phosphate decreases.
5)The solvent drag force has a minor role for the transport of these substances under normal conditions.

Sodium and Water Transport in the Small Intestine of the Dog

著者: ,   ,   ,   ,  

ページ範囲:P.321 - P.324

 The transport of sodium chloride and water by the intestine of the dog has been examined in vivo using radioactive sodium(Na24)and deuterium.
 The conclusions are as follows:(1)In the hypertonic solution, the movement of water from blood to the intestine is large in the early stage, but in hypotonic it is small.This fact indicates that the movement of water across the wall of the intestine is strongly influenced by the gradient of the osmotic pressure.
(2)The concentration of sodium of the influx solution is almost constant during the course of experiments, though the values vary in each case.Sodium and water move from blood to the intestine in a parallel manner.
(3)The ratio of Naeff to Naiff was some dependent on the concentration of sodium in the intestine.At the concentration of sodium in the intestine of 135mEq/l, which is slightly less than the concentration of sodium in the blood, the ratio approaches unity.The implication here is that the transport of sodium ion across the intestinal wall cannot be considered to occur merely by passive diffusion, and active transport must be postulated.

Water and Electrolyte Balance in Diuresis

著者: ,   ,   ,   ,  

ページ範囲:P.325 - P.327

 The external and internal exchange of sodium, potassium and water are different in various kinds of diuresis, suggesting that the transport of electrolytes through cell membranes may be changed in different modes, although aldosterone production should be studied in such diuresis.
 The positive balance of intracellular potassium in the diuresis with ACTH or adrenocortical steroids, may explain of their good clinical effects for nephrotic patients.

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生体の科学 第11巻 総目次

ページ範囲:P. - P.

基本情報

生体の科学

出版社:株式会社医学書院

電子版ISSN 1883-5503

印刷版ISSN 0370-9531

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