Änderung des Glukosetransports frischer menschlicher Erythrozyten bei längerer Inkubation

Summary Incubation of fresh defibrinated blood at 37°C increases the volume of red cells and decreases their permeation rate for glucose. The kinetics of sugar transport show direct proportionality between rate and the osmotic content of red cells. The measured volume changes and the changes of osmotic content calculated from the glucose permeation curves are in good agreement. Adenosine reconstitutes the increased volume and the decreased permeation rate in red cells. Therefore the decrease in permeation rate is explained by the increase in volume.     

Anesthetization of Planorbidae (Mollusca): methodology and pharmacology

Summary A slow drip application of sodium pentobarbital was used to anesthetizeHelisoma duryi for surgery. The use of a 0.01 M Trizma buffer in the anesthetic medium expedites recovery and appeared to reduce swelling of the pedal sinus. These observations are attributed to the restriction of pH favoring the entry of anesthetic into tissues and reducing osmotic stress experienced by the animal.Acknowledgment. This study was supported by a grant awarded by NSERC of Canada.     

Antidiuretic hormone involvement in the release of α-melanocyte-stimulating hormone by hyperosmotic stimuli

Summary In the normal Wistar rat, the plasma -MSH level was raised by hypertonic saline injection (as compared with control rats injected with isotonic saline). No such rise in -MSH followed hypertonic saline administration in the Brattleboro (hereditary diabetes insipidus) animal (compared to isotonic saline injected controls). It is suggested that, in the rat, endogenous antidiuretic hormone is involved in the secretory response of the pars intermedia to osmotic stimuli.     

Osmotic stress signaling via protein kinases

Plants face various kinds of environmental stresses, including drought, salinity, and low temperature, which cause osmotic stress. An understanding of the plant signaling pathways that respond to osmotic stress is important for both basic biology and agriculture. In this review, we summarize recent investigations concerning the SNF1-related protein kinase (SnRK) 2 kinase family, which play central roles in osmotic stress responses. SnRK2s are activated by osmotic stress, and a mutant lacking SnRK2s is hypersensitive to osmotic stress. Many questions remain about the signaling pathway upstream and downstream of SnRK2s. Because some SnRK2s also functions in the abscisic acid (ABA) signaling pathway, which has recently been well clarified, study of SnRK2s in ABA signaling can provide clues regarding their roles in osmotic stress signaling.     

Is the effect of diphenolic laxatives mediated via release of prostaglandin E?

The diphenolic laxatives, bisacodyl and phenolphthalein, and the osmotic laxative mannitol increase intestinal fluid volume in the rat colon in situ. The diphenolic laxatives stimulate the biosynthesis of prostaglandin E (PGE) whereas mannitol does not. Inhibition of PG-biosynthesis by pretreatment with indomethacin only reduces the effect of the diphenolic laxatives. It is suggested that diphenolic laxatives increase intestinal fluid volume via stimulation of PGE biosynthesis in the colon.     

Is the effect of diphenolic laxatives mediated via release of prostaglandin E?

Summary The diphenolic laxatives, bisacodyl and phenolphthalein, and the osmotic laxative mannitol increase intestinal fluid volume in the rat colon in situ. The diphenolic laxatives stimulate the biosynthesis of prostaglandin E (PGE) whereas mannitol does not. Inhibition of PG-biosynthesis by pretreatment with indomethacin only reduces the effect of the diphenolic laxatives. It is suggested that diphenolic laxatives increase intestinal fluid volume via stimulation of PGE biosynthesis in the colon.     

Free amino acids in some tissues of marine crustacea

Summary Free amino acids contained in extracts of crustaceans were separated and determined quantitatively by ion exchange chromatography. In the hepatoprancreas of the brachyuran crustaceanCarcinus maenas, glycine, arginine, proline and alanine constituted 78.7% of the total amino acid pool. InEriphia spinifrons andMaja verrucosa, glycine, alanine, lysine and leucine comprised 54.9–66.9% of the total content. In the muscle tissue of the macruran crustaceaPalaemon, glycine, arginine, proline and alanine were the most common free amino acids and comprised 70–95% of the total content. The high concentrations of some amino acids in tissues of crustaceans may play a role in intracellular osmotic regulation and also in the maintenance of ionic hydrogen concentration.Acknowledgments. The author wishes to thank Mr R. Mari for his skillful help in the amino acid analyses and Miss G. Princivalli for typing the mansucript.     

Fragile site Xq27 and metabolism of monocarbons

After confirming the increase of the fragility of the site Xq27 by methotrexate and its decrease by 5-formyltetrahydrofolate, it is observed that L-serine, 5-amino-levulinate and L-4-hydroxy-proline at millimolar concentrations, reduce considerably the frequency of the anomaly in lymphocyte cultures. The possible relationships between this chromosomal marker, the one carbon cycle,and mental deficiency of the patients, are discussed.     

A fast transient osmotic method. Simultaneous in vivo determination of the reflexion coefficient and of the permeability/filtration coefficient ratio of the pulmonary capillary endothelium in the dog]

Thermodynamic variables characterizing the transport of water and urea across Dog pulmonary capillary membrane were obtained in vivo by means of a pulse transient osmotic method. Results were inconsistent with the hypothesis of a homoporous membrane. When data were interpreted in terms of an exclusive water channel and of a shared pore pathway, the value of the pore reflexion coefficient was close to zero for urea.     

Vanadate: Non-selective inhibition of transepithelial transport of Na+, H+ and water

Summary In the isolated urinary bladder of the toad, 10^–5–10^–4M orthovanadate produces inhibition of the active transport of Na⁺ and H⁺ ions as well as of antidiuretic hormone-mediated osmotic flow of water. Since transport of H⁺ ions and osmotic water flow are not inhibited when (Na⁺+K⁺)-ATPase is inhibited by ouabain, biological actions of vanadate are not necessarily related to inhibition of (Na⁺+K⁺)-ATPase.This research was supported by grant AM-14915 from the National Institutes of Helath.     

Effect of orotic acid on liver glycogen of different animal species

Summary The effect of orotic acid on the liver glycogen content in the mice, frogs and catfish was studied. It was observed that the orotic acid significantly increases the glycogen content in the liver of mice and catfish as it does in rats. On the other hand it causes a fall of the glycogen level in frogs in experiments made both in autumn and spring. This effect was modified by amino acids administrated together with orotic acid.     

Effect of orotic acid on liver glycogen of different animal species.

The effect of orotic acid on the liver glycogen content in the mice, frogs and catfish was studied. It was observed that the orotic acid significantly increases the glycogen content in the liver of mice and catfish as it does in rats. On the other hand it causes a fall of the glycogen level in frogs in experiments made both in autumn and spring. This effect was modified by amino acids administered together with orotic acid.     

Effect of diet on osmotic water flow across rat colon mucosa

Summary Osmotic water flow across colon mucosa was increased in rats adapted to a high protein diet (HP) compared to rats fed a high carbohydrate diet (HC). The diet-induced change of the osmotic permeability of the colon is probably a manifestation of a regulatory mechanism controlling intestinal water absorption.Supported by the Deutsche Forschungsgemeinschaft.The technical assistance of Miss Margitta Hosser is gratefully acknowledged.     

Antidiuretic hormone involvement in the release of alpha-melanocyte-stimulating hormone by hyperosmotic stimuli

In the normal Wistar rat, the plasma alpha-MSH level was raised by hypertonic saline injection (as compared with control rats injected with isotonic saline). No such rise in alpha-MSH followed hypertonic saline administration in the Brattleboro (hereditary diabetes insipidus) animal (compared to isotonic saline injected controls). It is suggested that, in the rat, endogenous antidiuretic hormone is involved in the secretory response of the pars intermedia to osmotic stimuli.     

Zikadenendosymbiose: Eucyten-Struktur-, -Funktions- und -Evolutions-Modell

Summary The mitochondria can be considered as extremely integrated endosymbionts, according to the theory of the endosymbiontic origin of eucytes. Leafhoppers show also very integrated endosymbionts. Their protoplastoid-, rickettsia-and bacteria-like endosymbionts differ, according to grade, kind and supposed age of the relation, from the hypothetical type of mitochondria. Mitochondria and protoplastoids differ the least and show corresponding physiological behavior. Both have a regulative influence on pH and osmotic pressure of the eucyte and use probably the same mechanism of regulation. The protoplastoid endosymbiosis of leafhoppers can be regarded as a missing link between the temporary endosymbiosis of the bacteria and the permanent hypothetical one of the mitochondria. The leafhopper endosymbiosis is a suitable model for the analysis of structure, function and evolution of the eucyte.     

Concentration by the renal sac ofMolgula manhattensis of homarine,a nitrogenous compound

Summary An important compound in the renal sac fluid ofMolgula manhattensis is homarine. This substance may have a role in the osmotic adjustment of the molgulid renal sac.     

Mutants of Bacillus thuringiensis with altered sporulation: morphologic responses to several treatments applied in the exponential phase]

During log-phase of growth, wild strain and and oxytetracycline-resistant mutants with altered sporulation exhibit distinct responses to some treatments, autolysis, osmotic pressure, ultraviolet irradiation and bacteriophage infection.     

Nerve endings isolated from chick embryonic optic tectum. 2. Developmental aspects of synaptosomal membrane

Summary Fractions enriched in nerve endings (synaptosomes) have been isolated from chick embryonic optic tectum during development. After osmotic shock, these fractions appeared to be enriched in membranes which during development acquire typical features of mature synaptosomal membranes.     

Water movement between myocardial tissue and capillary blood during and after coronary reactive hyperemia as studied by continuous measurement of colloid osmotic pressure of cardiac venous blood

Summary Colloid osmotic pressure (COP) of blood from the great cardiac vein was continuously measured by the use of a membrane colloid osmometer during reactive hyperemia resulting from temporary occlusion of the anterior descending branch of left coronary artery. The COP increased sharply but transiently after the release, then it decreased below the initial level and gradually recovered. It was concluded that a measurable amount of water moved from the capillary blood into the myocardial tissue and then flowed back slowly into the capillary blood.     

False interpretation of membrane transport data due to osmotic volume changes of cells

Summary It is shown theoretically that in a nonsaturable transport system across a cell membrane, the kinetical analysis yields (erroneously) apparent saturation kinetics if osmotic volume changes of the cell occur and are not taken into account. Experimentally this is illustrated for the case of exit of glycerol from beef erythrocytes.