The role of mast cells in vascular permeability disorders in rats subjected to immobilization stress]

Disturbances of vascular permeability were studied by the "vascular labeling" technique in the mesentry during the 24-hour immobilization of rats. Administration of dimebolin (an antihistaminic preparation) decreased the number of labeled vessels and labeling intensity. This effect was expressed in the presence of mast cells only and was accompanied by the mast cell degranulation. The authors suppose that the mast cells contain a substance preventing the disturbance of vascular permeability and released during degranulation. Such substance might be heparin. Experiments showed that small doses of heparin failed to produce such effect. These results allowed one to conclude that mast cells played a double role in the mechanisms of disturbance of vascular permeability during immobilization--the damaging (by the action of histamine and serotonine) and the protective (by the released heparin) action.     

Influence of membrane physical state on lysosomal potassium ion permeability

Lysosomal permeability to potassium ions is an important property of the organelle. Influence of the membrane physical state on the potassium ion permeability of isolated lysosomes was assessed by measuring the membrane potential with bis(3-propyl-5-oxoisoxazol-4-yl)pentamethine oxonol and monitoring the lysosomal proton leakage with p-nitrophenol. The membrane fluidity of lysosomes was modulated by treatment with membrane fluidizer benzyl alcohol and rigidifier cholesteryl hemisuccinate. Changes in the membrane order were examined by steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene. The measurements of membrane potential and proton leakage demonstrated that the permeability of lysosomes to potassium ions increased with rigidification of their membranes by cholesteryl hemisuccinate treatment at 37 degrees C, and decreased with fluidization of their membranes by benzyl alcohol treatment at 2 degrees C. The changes in ion permeability could be recovered by fluidizing the rigidified membranes and rigidifying the fluidized membranes. The results suggest that the physical states of lysosomal membranes play an important role in the regulation of their K(+) permeability.     

Ethylene as a factor regulating the growth of pea epicotyls subjected to physical stress

Pea epicotyls (Pisum sativum, cv. Alaska) were enclosed in chambers in which their elongation was restricted by means of a foam neoprene stopper or by a medium of glass beads. These treatments increased evolution of ethylene and resulted in reduced length and increased diameter of both the internodes and the cells of the internodes. These responses increased with increasing degrees of restriction. A time-sequence study of the emergence of epicotyls through 90 mm of glass beads showed that an accelerated evolution of ethylene preceded a reduction in elongation. As the epicotyls elongated through the glass bead medium and less resistance was encountered, evolution of ethylene declined and rapid elongation was resumed. The morphological and anatomical effects of a 120-mm column of glass beads were duplicated by applied ethylene concentrations of 0.2 ppm or less. Evolution of CO₂ was inhibited slightly by the ethylene treatments. The data indicate that production of ethylene by pea epicotyls is increased by nonwounding physical stress, and that the ethylene acts as an endogenous growth regulator, decreasing elongation and increasing diameter in response to increasing increments of stress.     

Mechanisms of catecholamine synthesis disorders in the adrenals of rats subjected to physical fatigue]

There was a depression of transformation of noradrenaline, DOPA and thyrosine added in vitro, into catecholamines in the adrenal glands of rats after swimming for a period of 8 hours. This permitted to suppose a depression of the activity of phenylethanolamine-N-methyl-transpherase, DOPA-decarboxylase, and, possibly, of tyrosine hydroxylase under these conditions. After the end of swimming, in the presence of 1-tyrosine, there is at first an activation of noradrenaline synthesis, and then there occurs a gradual normalization (on the 7th day) of adrenaline formation. In rats trained for a period of 2 months the extent of reduction of the catecholamine synthesis in the adrenal glands in response to the 8-hour swimming was much less in comparison with the untrained aniamals.     

Depression of sink activity precedes the inhibition of biomass production in tomato plants subjected to potassium deficiency stress

Tomato [Solanum lycopersicum (formerly Lycopersicon esculentum) L. cv. Momotarou] plants were grown hydroponically inside the greenhouse of Hiroshima University, Japan. The adverse effects of potassium (K) deficiency stress on the source-sink relationship during the early reproductive period was examined by withdrawing K from the rooting medium for a period of 21 d. Fruits and stem were the major sink organs for the carbon assimilates from the source. A simple non-destructive micro-morphometric technique was used to measure growth of these organs. The effect of K deficiency was studied on the apparent photosynthesis (source activity), leaf area, partitioning (13)C, sugar concentration, K content, and fruit and stem diameters of the plant. Compared with the control, K deficiency treatment severely decreased biomass of all organs. The treatment also depressed leaf photosynthesis and transport of (13)C assimilates, but the impact of stress on these activities became evident only after fruit and stem diameter expansions were down-regulated. These results suggested that K deficiency diminished sink activity in tomato plants prior to its effect on the source activity because of a direct effect on the water status of the former. The lack of demand in growth led to the accumulation of sugars in leaves and concomitant fall in photosynthetic activity. Since accumulation of K and sugars in the fruit was not affected, low K levels of the growing medium might not have affected the fruit quality. The micro-morphometric technique can be used as a reliable tool for monitoring K deficiency during fruiting of tomato. K deficiency directly hindered assimilate partitioning, and the symptoms were considered more detrimental compared with P deficiency.     

Effect of naphthenic acids on the permeability of ascitic tumor cells to potassium ions]

Ascite cells were treated with naphthenic acid preparation, containing a mixture of naphthenic acids with average molecular weight equal to 240, and with a fraction of this preparation differing in the boiling temperature. A 5-10(-7)M and higher concentrations of the preparation and its fraction brought about an increased permeability in ascite cells for K-ions. The effectiveness of naphthenic acids is associated with their hydrophobic properties, which was characterized in the present communication by the value of hydrophilic-lipophilic balance calculated according to the Davies formula.     

The permeability of muscle capillaries to horseradish peroxidase

The main objective of this study was to determine the pathways by which horseradish peroxidase (HRP) can cross the endothelium of muscle capillaries. Specimens of mouse diaphragm were fixed for cytochemical analysis at various intervals after intervenous injection of 0.5 mg HRP, at 4 min after intervenous injection of varied amounts of HRP, and at 4 min after intervenous injections in various volumes of isotonic NaCl. Our findings indicate that endothelial junctions serve as a barrier which may allow passage of very limited amounts of HRP. They also suggest that endothelial vesicles transfer HRP from the capillary lumen to the pericapillary interstitium as well as in the reverse direction. Increasing the volume of solution injected to approximately 30% of total blood volume did not increase the amount of HRP that left the capillary lumen. Our results with HRP do not provide clearcut evidence that endothelial junctions are the site of the small pore.     

The permeability of the human erythrocyte to sodium and potassium

Measurements have been made on the permeability of the human erythrocyte to Na and K in vitro, using radioactive tracers to observe the system in the steady state. The average inward K flux is 1.67 m.eq./liter cells hour, and the apparent activation energy is 12,300 ± 1300 calories/mol. The inward K flux is independent of the external K concentration in the range of concentrations studied (4 to 16 m.eq. K/liter plasma). Rb appears to compete with K for transport into the cell, whereas Na and Li do not. The average inward Na flux is 3.08 ± 0.57 m.eq. Na/liter cells hour, and the apparent activation energies are 20,200 ± 2700 calories/mol for inward transport, and 14,900 ± 3,400 calories/mol for outward transport. The inward Na flux is dependent on the external Na concentration, but not in a linear fashion. Li appears to compete with Na for inward transport, whereas K and Rb do not. An approximate maximum estimate shows that the energy required for cation transport is only 8.8 calories/mol liter cells hour of the 110 calories/mol liter cells hour available from the consumption of glucose. A working hypothesis for the transport of Na and K is presented.     

Plasma cortisol and beta-endorphin in horses subjected to electro-acupuncture for cutaneous analgesia

Electro-acupuncture (EA) treatment of horses to induce cutaneous analgesia also increased plasma concentrations of beta-endorphin (beta-EP) and cortisol. The magnitude of these increases did not relate consistently to the degree of EA-induced analgesia. Respiration and heart rates were also markedly increased during EA treatment. Intact female horses had higher packed cell volume and plasma beta-EP as well as lower plasma total protein than castrated male horses. Plasma cortisol, heart rate, and respiration rate did not differ significantly between sexes. None of the parameters measured before or during EA treatment provided an explanation for the differential cutaneous analgesia which depended on sex of subject and locus of stimulation as reported elsewhere.     

Lower serum IgA levels in horses kept under intensive sanitary management and physical training

Quantity and variety of environmental antigens, age, diet, vaccine protocols, exercising practice and mucosal cytokine microenvironment are factors that influence serum immunoglobulin (Ig) levels. IgA, IgG, IgG(T) and IgM were quantified in 60 horses, which were classified into two groups, 'intensive' or 'relaxed', according to sanitary standards of the facilities and physical exercise to which animals were subjected to. The 'intensive' group presented lower means for all isotypes, but only IgA presented a significant (P < 0.0064) difference when compared to the 'relaxed' group. This suggests that mucosal immunity found in the 'intensive' group is lower when compared to the 'relaxed' group. Our data suggest that athlete horses may be less poised to mount an effective mucosal immunity response to environmental challenges and should not be considered by the same perspectives as a free-ranging horse.     

Ultrastructural study of the permeability of the guinea-pig placenta to horseradish peroxidase

Summary Horseradish peroxidase (HRP) was used to study macromolecule permeation into the guinea-pig placenta perfused in situ. When tissue culture medium 199 (TC 199) was used as fetal-side perfusate, the tracer reaction product was found only lining the fetal endothelium. When a longer period of perfusion with HRP in TC 199 was used, a small amount of reaction product was found in the subendothelial space and syncytiotrophoblastic vesicles, but not in maternal lacunae. In similar experiments using a Krebs bicarbonate Ringer (KRBG) as perfusate the tracer was found (i) lining the fetal endothelium, (ii) in the lateral intercellular spaces of the endothelium, (iii) in the subendothelial space, and (iv) in the maternal lacunae.It is therefore evident that the vehicle influenced the permeability of the guinea-pig placenta to horseradish peroxidase. As other studies have shown that perfusion of the fetal side with salt solution increases pore size, the results with TC 199 are regarded as more representative of the situation in the intact animal. It is therefore suggested that the fetal endothelium of the guinea-pig placenta may be largely impermeable to molecules of the size of horseradish peroxidase (4 nm) or larger.     

The permeability of the guinea pig cochlear capillaries to horseradish peroxidase

Summary Guinea pigs were given horseradish peroxidase intracardially. Examination of the cochlear capillaries 2 to 10 min after the injection revealed that the capillaries of the vascular stria are permeable to the peroxidase whereas the capillaries of the basilar membrane, the spiral ligament, and the spiral prominence are impermeable.

---

Zusammenfassung Meerrettich-Peroxydase wurde Meerschweinchen intracardial verabfolgt. Die Untersuchung der Kapillaren der Schnecke 2–10 min nach der Injektion zeigte, daß die Kapillaren der Stria vascularis für die Peroxydase permeabel waren, jene der Membrana basilaris, des Ligamentum spirale und der Prominentia spiralis dagegen impermeabel sind.

     

Matrix magnesium and the permeability of heart mitochondria to potassium ion

Isolated beef heart mitochondria were treated with A23187 in the presence of different concentrations of Mg2+ or EDTA to establish varying levels of total mitochondrial Mg2+. The Mg2+ content was related to the rate of passive swelling of the mitochondria in potassium acetate and other potassium salts in which swelling is presumed to depend on K+ entry via an endogenous K+/H+ antiport. Swelling in these salts does not commence until Mg2+ has been depleted from an initial value of 36 nmol X mg-1 of protein to 8 nmol/mg-1, or less. Below this level, swelling increases linearly with decreasing Mg2+ to a maximum rate at 2 nmol of Mg2+ X mg-1. Rotenone-treated heart mitochondria suspended in 75 mM potassium acetate at pH 7.80 show no delta pH by 5,5-dimethyl-2,4-oxazolidinedione distribution. Distribution of methylamine also shows essentially no delta pH under these conditions when allowance is made for binding of [14C]methylamine by mitochondrial membranes under these conditions. Addition of A23187 results in a small and transient delta pH (delta pH less than 0.14, acid interior) as measured by methylamine distribution. Estimation of the maximum matrix free Mg2+ concentration from the maximum delta pH observed and the external free Mg2+ concentration at equilibrium with A23187 shows that swelling is not initiated until matrix free Mg2+ is decreased to below 150 microM. An independent estimate of free Mg2+ using a null-point procedure gives a lower, but quite similar value (50 microM) for maximum matrix free Mg2+ when swelling commences. The large depletion of total and free Mg2+ that is required to activate swelling in potassium acetate (and presumably K+/H+ antiport activity) does not appear to be compatible with previous indications that free Mg2+ acts as a "carrier brake" to regulate K+ extrusion from the mitochondrion on such an antiport (Garlid, K. D. (1980) J. Biol. Chem. 255, 11273-11279). The removal of a tightly bound component of mitochondrial Mg2+ is closely related to increased K+ permeability and increased passive swelling in potassium salts. This Mg2+ appears to play a role in the maintenance of mitochondrial membrane structure and integrity.     

Effect of aspirin on serum lipoprotein profile in rats subjected to myocardial stress by isoproterenol.

The effect of isoproterenol on the levels of serum lipoprotein profile were studied in rats. Rats were treated with isoproterenol (200 mg/100 g body weight, sc twice at an interval of 24 hr) for 2 days. Aspirin was administered orally 1.2 mg/100 g body weight, daily for 60 days. Isoproterenol treated rats showed decrease in the activities of hepatic and extrahepatic lipoprotein lipase. HDL cholesterol level was found to be decreased, significantly with increase in LDL cholesterol in isoproterenol treated rats. Aspirin treated rats showed marked reversal of these metabolic changes. The lipoprotein changes were minimum in rats treated with both aspirin and isoproterenol.     

Proton permeability and the regulation of potassium permeability in mitochondria by uncoupling agents

Summary The addition of agents that uncouple electron transfer from energy conservation (uncouplers) to state 4 mitochondria causes the following ion movements: K⁺ is extruded from the mitochondria in association with phosphate and possibly other anions, but not H⁺. Endogenous Ca⁺⁺ is extruded from the mitochondria, and H⁺ moves in to counter-balance the Ca⁺⁺ movement; some phosphate movement may be associated with Ca⁺⁺ extrusion. The rate and extent of K⁺ extrusion induced by uncoupler is dependent on the concentrations of external phosphate and divalent ions. Phosphate induces K⁺ extrusion, while Mg⁺⁺ and Mn⁺⁺ inhibit it. TheV _max of K⁺ transport is 300 moles K⁺/g protein per min. The K _m for FCCP-induced potassium extrusion is 0.25 M at pH 7.4. The inhibitory effect of Mg⁺⁺ is noncompetitive with respect to uncoupler concentration but competitive with respect to phosphate concentration. The experimental evidence does not support the existence of high H⁺ permeability in the presence of uncoupler. A correlation is observed between the rate of K⁺ extrusion and the energy reserves supplied from the high energy intermediate. The action of uncoupler in inducing K⁺ permeability is considered to arise through its action in depleting the energy reserves of mitochondria rather than through a specific activating effect of permeability by the uncoupler itself. The relationship of membrane potential to regulation of K⁺ permeability is discussed.     

Changes in the neuroendocrine regulation of adaptive behavior in rats subjected to stress in the late prenatal ontogenesis]

Female rats were subjected from the 14th to 17th day of pregnancy to immobilisation under conditions of 1-hour daily bright illumination. On the 20th day, contents of testosterone and estradiol was decreased with no sex difference in their level in the pregnant female rats' blood and in the amniotic fluid. Sex differences were flattened in 1-month litter both in the androgen and oestrogen contents and in adaptive behaviour. In prenatally stressed males, motor activity was inhibited and anxiety was enhanced as compared with the control. At one and a half months of age, the consequences of the prenatal stress disappeared and then reappeared after sexual maturation but with an opposite trend. Adaptive behaviour of adult males was less flexible and revealed no age-dependent oscillations inherent in the control animals. Prenatal stress while preventing the maximal raise of sex steroids in the blood shifts sex differentiation of the adaptive behaviour toward demasculinization.