Sodium and potassium effects on skeletal muscle microsomal adenosine triphosphatase and calcium uptake

The relationship between the (Na(+) and K(+))-activated adenosine triphosphatase enzyme system implicated in sodium-transport by cell membranes and the calcium-activated adenosine triphosphatase, which is generally associated with calcium uptake, was examined in microsomes from skeletal muscle. Whereas sodium and potassium did not modify the relatively low adenosine triphosphatase activity seen in the absence of calcium, a pattern similar to that of the sodium-transport enzyme system was seen afer the addition of CaCl(2). The calcium-activated adenosine triphosphatase was stimulated equally by sodium or potassium alone, but both the rate and extent of calcium uptake were enhanced more by potassium than by sodium at concentrations below 0.12 mole per liter. In the absence of either of these ions addition of calcium failed to activate adenosine triphosphatase although significant amounts of calcium were taken up by the microsomes.     

Promotion of tubulin assembly by aluminum ion in vitro

It has been proposed that aluminum ion is a contributing factor in a variety of neurological diseases. In many of these diseases, aberrations in the cytoskeleton have been noted. The effects of aluminum ion on the in vitro assembly of tubulin into microtubules has been examined by determining the association constants for the metal ion-guanosine triphosphate-tubulin ternary complex required for polymerization. The association constant for aluminum ion was approximately 10(7) times that of magnesium ion, the physiological mediator of microtubule assembly. In addition, aluminum ion at 4.0 X 10(-10) mole per liter competed effectively with magnesium ion for support of tubulin polymerization when magnesium ion falls below 1.0 millimole per liter. The microtubules produced by aluminum ion were indistinguishable from those produced by magnesium ion when viewed by electron microscopy, and they showed identical critical tubulin concentrations for assembly and sensitivities to cold-induced depolymerization. However, the rate of guanosine triphosphate hydrolysis and the sensitivity to calcium ion-induced depolymerization, critical regulatory processes of microtubules in vivo, were markedly lower for aluminum ion microtubules than for magnesium ion microtubules.     

Colloid transport of plutonium in the far-field of the Mayak Production Association, Russia

Sorption of actinides, particularly plutonium, onto submicrometer-sized colloids increases their mobility, but these plutonium colloids are difficult to detect in the far-field. We identified actinides on colloids in the groundwater from the Mayak Production Association, Urals, Russia; at the source, the plutonium activity is approximately 1000 becquerels per liter. Plutonium activities are still 0.16 becquerels per liter at a distance of 3 kilometers, where 70 to 90 mole percent of the plutonium is sorbed onto colloids, confirming that colloids are responsible for the long-distance transport of plutonium. Nano-secondary ion mass spectrometry elemental maps reveal that amorphous iron oxide colloids adsorb Pu(IV) hydroxides or carbonates along with uranium carbonates.     

Serum osmolality in the coelacanth, Latimeria chalumnae: urea retention and ion regulation

Samples of blood (hemolyzed) were obtained from the renal vein, the hepatic portal vein, and the heart of a freshly thawed specimen of Latimeria chalumnae. The coelacanth uses high concentrations of urea to maintain its serum osmolality at approximately that of sea water. The mean value for the total osmolality was 1181 milliosmoles per liter. The mean values (milliequivalents per liter) were: for sodium, 181; for potassium, 51.3; for calcium, 6.9; for magnesium, 28.7; for chloride, 199; and for bicarbonate, 4.7. The mean urea concentration was 355 millimoles per liter, and the mean nonprotein nitrogen was 1343 milligrams percent. Heart blood showed significantly lower values for osmolality (921 milliosmoles per liter) and nonprotein nitrogen (1030 mg percent) and was probably less severely contaminated with products of protein breakdown. Fluid from the anterior chamber of the eye showed values of 952 milliosmole/liter; the urea value for this fluid was 303 mmole/liter, and the magnesium was 7.3 meq/liter. The magnesium value for the aqueous humor was used to correct the abnormally high concentrations in the hemolyzed serum. The high level of serum potassium also was attributed to hemolysis.     

Quinacrine (atebrin): mode of action

Quinacrine at a concentration of 8 x 10(-4) mole per liter is bactericidal for Escherichia coli, blocks DNA synthesis, and inhibits the syntheses of RNA and protein strongly. At a concentration of 2x 10(-4) mole per liter, the drug is bacteriostatic, the syntheses of protein and DNA (but not that of RNA) are partially inhibited, and the bacteria grow into giant filaments. Impairment of DNA replication is proposed as the mode of action of quinacrine.     

Cyclic adenosine monophosphate: potassium-dependent action on vascular smooth muscle membrane potential

Dibutyryl cyclic adenosine monophosphate and theophylline hyperpolarize smooth muscle of rabbit main pulmonary artery in low concentrations of potassium (1 millimole per liter) but do not have a significant effect on the membrane potential in the presence of high concentrations of potassium (10 millimoles per liter). The dependence of the hyperpolarizing effect on a low external concentration of potassium is similar to that observed with isoproterenol. Prior treatment with theophylline potentiated the hyperpolarizing action of isoproterenol. These findings are compatible with the assumption that potassium-dependent, beta-adrenergic hyperpolarization is mediated by cyclic adenosine monophosphate.     

Adenosine 3',5'-monophosphate-dependent protein kinase from brain

Adenosine 3',5'-monophosphate at a concentration of 5 x 10(-7) mole per liter causes a 400 percent increase in the rate of phosphorylation of histone catalyzed by a partially purified enzyme preparation from rabbit brain. The data provide the first direct evidence of a biochemical action of adenosine 3',5'-monophosphate in the brain.     

Human embryonic kidneys in organ culture: abnormalities of development induced by decreased potassium

Human embryonic kidneys of 5 to 12 weeks of gestation were grown in organ culture. Potassium concentrations of 3 to 6 milliequivalents per liter produced decreased ureteral bud branching, failure of nephron induction, and occasional cystic dilatations of the ureteral bud. Normal development of the kidney occurred at potassium concentrations of 6.5 to 10 milliequivalents per liter. These studies confirm the importance of relative stability of the potassiunm concentration in the development of the embryonic kidney.     

钾钠电极互参电位法同时测定土壤浸提液中钾和钠

以钾钠电极互为参比,采用一次标准加入法可以分别求出钾钠离子的浓度。电极的测定斜率为:钾53.9mV,钠52.7mV。标准混合物的测定误差分别为:钾-0.23％～+2.4％,钠-1.5％～+4.7％。实验中采用0.5mol/L BaCl_2溶液作为浸提剂及离子强度调节剂,电位法同时测定了5种不同盐化程度的(土娄)土、潮土及水稻土中钾钠的含量。回收率为:钾98.7％～102％,钠98.6％～102％.以火焰光度法作为对照,其结果与电极法完全一致。     

Bradykinin inhibition by butylated hydroxyanisole

Concentrations of butylated hydroxyanisole as low as 8 x 10(-9) mole per liter can inhibit detectably the contraction of smooth muscle elicited by bradykinin. The mechanism of the inhibitory effect of this food grade anti-oxidant is apparently complex, and the effect is only partially reversible.     

Indoleacetic acid oxidase activity of apoperoxidase

The conventional activity of electrophoretically purified horseradish peroxidase toward guaiacol, pyrogallol, 2,6-dimethoxyphenol, and benzidine is abolished by removal of the heme prosthetic group with a mixture of cold acetone and hydrogen chloride. The apoenzyme, though devoid of peroxidase activity, retains its activity as an indoleacetic acid oxidase when it is supplied with 10(-5) mole of manganous ion and 2,4-dachlorophenol per liter. This oxidase activity is cyanide-sensitive; azide also inhibits under specific conditions of both pH and cofactor concentration. Partial restoration of the peroxidase activity by recombination of apoprotein with heme produces no effect on the oxidase activity, except that cofactors are no longer absolutely required. Therefore, it appears that the activity of peroxidase as an indoleacetic acid oxidase need not directly involve the heme prosthetic group, or that manganous ions and dichlorophenol can substitute for the heme group in the reaction between indoleacetic acid and oxidase.     

Cytoplasmic and chloroplast ribosomes of Chlamydomonas: ultracentrifugal characterization

Ribosomes isolated from the cytoplasmic and chloroplast fractions of Chlamydomonas were characterized in the ultracentrifuge. The cytoplasmic ribosomes belong to the 80S class of ribosomes, and, like animal ribosomes, dissociate to 60, 50, and 40S subunits. However, like the ribosomes of microorganisms, they contain smaller RNA's, 24 and 16S, and require 0.01 mole of magnesium ions per liter for stability. Chloroplast ribosomes are 70S like those of higher plants but are very unstable. A stable 50S subunit has been observed.     

Activation volume for creep in the upper mantle

The activation volume for creep, V*, of olivine-rich rocks has been determined in pressure-differential creep experiments on dunite at temperatures from 1100 degrees to 1350 degrees C and confining pressures from 5 to 15 kilobars. Values of V* range from 10.6 to 15.4 cubic centimeters per mole with a mean value of 13.4 cubic centimeters per mole, near that expected for oxygen ion self-diffusion. The quantity V* is incorporated into existing flow equations; in combination with observations on naturally deformed mantle xenoliths, estimates are given of the variation with depth of stress, strain rate, and viscosity.     

Gibberellic acid: a growth factor in the unicellular alga Gymnodinium breve

Gibberellic acid stimulates growth in the unicellular alga Gymnodinium breve (dinoflagellate). The maximum effect was obtained with 10(-7) molar gibberellic acid, whereas concentrations greater than 5 x 10(-7) mole per liter were inhibitory. The effect of the compound is observed as a marked shortening of the lag period, which is normally 6 to 8 days after innoculation.     

Cypridina bioluminescence: light-emitting oxyluciferin-luciferase complex

Fluorescence of Cypridina oxyluciferin is greatly enhanced when it is bound to luciferase; the spectrum is thereby shifted, so that it corresponds precisely to the emission spectrum characteristic of the bioluminescentoxidation of luciferin. Thus the oxyluciferin-luciferase complex is the lightemitter. The binding is equimolar, with dissociation constant K(D) equal to 3x 10(-7) mole per liter. The molecular weight of the luciferase, according to three different methods, is between 52,000 and 57,000; molecular activities of luciferase for the bioluminescence reaction and for the hydrolysis of oxy-luciferin are 1600 and 2 per minute, respectively.     

Salicylate: effect on membrane permeability of molluscan neurons

Identified cells in the buccal ganglion of the marine mollusk Navanax inermis were exposed to salicylate (1 to 30 millimoles per liter) for short periods. Salicylate increased the permneability to potassium and decreased the permeability to chloride in a reversible, dose-dependent manner, producing a concomitant increase in membrane potential and a decrease in membrane resistance. These events would reduce the output from, as well as the effectiveness of synaptic input to, a particular neuron.     

Sodium and potassium activities in normal and "sodium-rich" frog skeletal muscle

In frog sartorius muscles immersed for 2 hours at 26 degrees C in normal Ringer solution, the intrafiber potassium concentration, C(K)(in millimoles per liter), was 123 +/- 2 (mean value plus or minus standard error), and the potassium activity, a(K) (in millimoles per liter), was 90 +/- 1.0. The corresponding sodium concentration and activity were 20 +/- 1 and 6.5 +/- 0.4, respectively. After overnight immersion in K+-free Ringer solution the values were: CK, 97 +/- 2; aK, 81.5 +/- 1.6; CNa, 47 +/- 2; and aNa, 11.2 +/- 0.6. The changes in aK and aNa during storage were not consistent with an exchange between predominantly "free" fiber K+ and external Na+. These results suggest that the Na+ taken up during overnight immersion largely replaced adsorbed or sequestered K+ in the fibers.     

Free-radical oxidants in natural waters

Photooxidation of cumene (isopropylbenzene) and pyridine in dilute solution in natural waters gives products characteristic of reactions with alkylperoxy (RO(2).) and hydroxyl (HO.) radicals. On the basis of the rates of formation of the products, the average concentrations of RO(2). and HO. are estimated to be about 10(-9) and 10(-17) mole per liter, respectively. The concentration of RO(2). is large enough that, for some classes of reactive chemicals, oxidation can be an important process in natural waters.     

Adsorption of alkyl trimethylammonium chlorides at a porous glass-potassium chloride solution interface

The adsorption of dodecyl, tetradecyl, hexadecyl, and octadecyl trimethylammonium chlorides at an interface between porous glass and potassium chloride solution has been characterized by measurements of membrane potentials. The specific potential Phi is 0.97 kT per methylene group (where k is the Boltzmann constant and T is the absolute temperature) or 580 calories per mole at 23 degrees C.     

Saxitoxin and tetrodotoxin: comparison of nerve blocking mechanism

Saxitoxin at concentrations of 3 x 10(-8) to 3 x 10(-7) mole per liter blocks the conduction of lobster giant axon with no change in resting potential. Recovery of washed axons is faster in those that had been treated with saxitoxin than it is in those that were treated with tetrodotoxin. Peak transient increase in nerve membrane conductance is selectively blocked by saxitoxin with no change in late steady-state increase in conductance. The major mechanism of saxitoxin blockage is the same that of tetrodotoxin blockage.