scholarly journals THE KINETICS OF PENETRATION

1936 ◽  
Vol 19 (3) ◽  
pp. 397-418 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
External Solution ◽  
Marked Contrast ◽  
External Concentration ◽  
Simple Diffusion ◽  
Strong Base ◽  
Protoplasmic Surface ◽  
Total Sulfide ◽  
Total Ammonia ◽  
Kinetics Of

The rate of entrance of H2S into cells of Valonia macrophysa has been studied and it has been shown that at any given time up to 5 minutes the rate of entrance of total sulfide (H2S + S-) into the sap is proportional to the concentration of molecular H2S in the external solution. This is in marked contrast with the entrance of ammonia, where Osterhout has shown that the rate of entrance of total ammonia (NH3 + NR4+) does not increase in a linear way with the increase in the external concentration of NH3, but falls off. The strong base guanidine also acts thus. It has been shown that the rate of entrance of H2S is best explained by assuming that it enters by diffusion of molecular H2S through the non-aqueous protoplasmic surface. It has been pointed out that the simple diffusion requires that the rate of entrance might be expected to be monomolecular. Possible causes of the failure of H2S to follow this relationship have been discussed.

scholarly journals THE KINETICS OF PENETRATION

1937 ◽  
Vol 20 (5) ◽  
pp. 737-766 ◽  
Author(s):  
A. G. Jacques
Keyword(s):  
Sea Water ◽  
Surface Layers ◽  
Marked Contrast ◽  
External Concentration ◽  
Protoplasmic Surface ◽  
Kinetics Of ◽  
External Ph

When 0.1 M NaI is added to the sea water surrounding Valonia iodide appears in the sap, presumably entering as NaI, KI, and HI. As the rate of entrance is not affected by changes in the external pH we conclude that the rate of entrance of HI is negligible in comparison with that of NaI, whose concentration is about 107 times that of HI (the entrance of KI may be neglected for reasons stated). This is in marked contrast with the behavior of sulfide which enters chiefly as H2S. It would seem that permeability to H2S is enormously greater than to Na2S. Similar considerations apply to CO2. In this respect the situation differs greatly from that found with iodide. NaI enters because its activity is greater outside than inside so that no energy need be supplied by the cell. The rate of entrance (i.e. the amount of iodide entering the sap in a given time) is proportional to the external concentration of iodide, or to the external product [N+]o [I-lo, after a certain external concentration of iodide has been reached. At lower concentrations the rate is relatively rapid. The reasons for this are discussed. The rate of passage of NaI through protoplasm is about a million times slower than through water. As the protoplasm is mostly water we may suppose that the delay is due chiefly to the non-aqueous protoplasmic surface layers. It would seem that these must be more than one molecule thick to bring this about. There is no great difference between the rate of entrance in the dark and in the light.

scholarly journals THE KINETICS OF PENETRATION

1935 ◽  
Vol 18 (6) ◽  
pp. 967-985 ◽  
Author(s):  
A. G. Jacques ◽  
W. J. V. Osterhout
Keyword(s):  
Potassium Concentration ◽  
External Solution ◽  
Potassium Bicarbonate ◽  
External Concentration ◽  
Definite Answer ◽  
External Potassium ◽  
The Subject ◽  
Kinetics Of ◽  
External Ph ◽  
Nitella Flexilis

The rate of entrance of potassium into Nitella flexilis has been investigated, and it has been shown that (a) at the concentrations studied the rate is independent of the external pH between 6 and 8 but it is possible that at lower concentrations a dependence may be found; (b) that it does not vary much with the external potassium concentration between 0.01 and 0.001 M, but appears to vary more with the potassium concentration below this limit. It has also been shown that the rate is independent of the illumination, in contrast with the penetration of halides into Nitella clavata studied by Hoagland. It has been found that potassium leaves the cells in distilled water, and since this does not seem to be the result of injury, there is apparently a concentration between 0 and 0.0001 M at which potassium neither enters nor leaves the cell. In Valonia increase of external potassium increases the rate of entrance as shown in the increase in moles of potassium in the sap. In Nitella this is true below an external concentration of 0.001 M. In Valonia this increase is paralleled by the increase in entrance of water so that little or no change in concentration occurs, but in Nitella no growth occurred during the experiment and in consequence the concentration of potassium in the sap increased. It has been shown that the potassium content of the raw gelatinous sap is no greater than that of its ultrafiltrate, so that it is not possible to assume that any of the potassium is bound up in the cell in colloidal compounds. It has been pointed out that all the gradients between the sap and the external solution are unfavorable to the entrance of potassium except the potassium bicarbonate gradient. However, on other grounds entrance as potassium bicarbonate is not considered to be very probable. Various modes of entrance are discussed and it has been concluded that the subject must be investigated further before a definite answer can be given.

scholarly journals KINETICS OF PENETRATION

1934 ◽  
Vol 17 (3) ◽  
pp. 469-480 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Kamerling ◽  
W. M. Stanley
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Molecular Form ◽  
External Solution ◽  
Living Cells ◽  
Protoplasmic Surface ◽  
Weak Electrolytes ◽  
Ionic Mobilities ◽  
Aqueous Layer ◽  
Kinetics Of

In some living cells the order of penetration of certain cations corresponds to that of their mobilities in water. This has led to the idea that electrolytes pass chiefly as ions through the protoplasmic surface in which the order of ionic mobilities is supposed to correspond to that found in water. If this correspondence could be demonstrated it would not prove that electrolytes pass chiefly as ions through the protoplasmic surface for such a correspondence could exist if the movement were mostly in molecular form. This is clearly shown in the models here described. In these the protoplasmic surface is represented by a non-aqueous layer interposed between two aqueous phases, one representing the external solution, the other the cell sap. The order of penetration through the non-aqueous layer is Cs > Rb > K > Na > Li. This will be recognized as the order of ionic mobilities in water. Nevertheless the movement is mostly in molecular form in the nonaqueous layer (which is used in the model to represent the protoplasmic surface) since the salts are very weak electrolytes in this layer. The chief reason for this order of penetration lies in the fact that the partition coefficients exhibit the same order, that of cesium being greatest and that of lithium smallest. The partition coefficients largely control the rate of entrance since they determine the concentration gradient in the non-aqueous layer which in turn controls the process of penetration. The relative molecular mobilities (diffusion constants) in the non-aqueous layer do not differ greatly. The ionic mobilities are not known (except for K+ and Na+) but they are of negligible importance, since the movement in the non-aqueous layer is largely in molecular form. They may follow the same order as in water, in accordance with Walden's rule. Ammonium appears to enter faster than its partition coefficient would lead us to expect, which may be due to rapid penetration of NH3. This recalls the apparent rapid penetration of ammonium in living cells which has also been explained as due to the rapid penetration of NH3. Both observation and calculation indicate that the rate of penetration is not directly proportional to the partition coefficient but increases somewhat less rapidly. Many of these considerations doubtless apply to living cells.

scholarly journals EVIDENCE OF ACTIVE TRANSFER OF CERTAIN NON-ELECTROLYTES ACROSS THE HUMAN RED CELL MEMBRANE

1948 ◽  
Vol 31 (6) ◽  
pp. 505-527 ◽  
Author(s):  
Paul G. LeFevre
Keyword(s):  
Cell Membrane ◽  
Sulfhydryl Group ◽  
Red Cell ◽  
Volume Changes ◽  
Red Cell Membrane ◽  
Simple Diffusion ◽  
Active Transfer ◽  
Saline Solutions ◽  
Kinetics Of ◽  
Human Red Cell Membrane

1. Permeability of the human erythrocyte to glycerol, as indicated by the course of hemolysis and volume changes, is depressed by Cu++, Hg++, I2, p-chloromercuribenzoate, and phlorhizin, without effecting general permeability changes. In so far as tested (Cu++, p-ClHgB), these inhibitors delay exit of glycerol from the cell as well as its entry. 2. Permeability to glucose is similarly depressed by I2 and phlorhizin, and is extremely sensitive to Hg++ and p-chloromercuribenzoate, but is not affected by Cu++. An extensive series of other enzyme poisons is without effect in either system. 3. The effects of the sulfhydryl inhibitors are prevented or reversed in the presence of glutathione, cysteine, etc. 4. The kinetics of the volume changes in glucose-saline solutions indicates a mechanism for transport of glucose into the cell, regulated by the existing intracellular concentration, rather than by simple diffusion gradients. 5. The intermediation of a sulfhydryl group at the cell surface, probably an enzymatic phosphorylation, is suggested as an essential step in the passage of glycerol, glucose, and other like substances, across the human red cell membrane.

scholarly journals Kinetic Study of Carbon Dioxide Reaction with Binding Organic Liquids

2019 ◽  
Vol 26 (1) ◽  
pp. 26-32
Author(s):  
Sanaa Rabie Saleh ◽  
Ahmed Daham Wiheeb
Keyword(s):  
Reaction Kinetics ◽  
Co2 Capture ◽  
Rapid Change ◽  
Reaction System ◽  
Organic Liquids ◽  
Co2 Absorption ◽  
Strong Base ◽  
Stirred Cell ◽  
Kinetics Of Reaction ◽  
Kinetics Of

Binding organic liquids are a strong base of amidine have been used for CO2 capture. Up to now, there is no known datum on the reaction kinetics of CO2 with 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN). In this paper, Kinetics of reaction between CO2 and DBN/MDEA in 1-Pentanol were performed utilizing the stirred cell reactor with DBN concentration (2 – 2.9 M) and at room temperature. The reaction path was qualified using zwitterion and the termolecular mechanism. From the kinetic datum with DBN concentrations (2 – 2.9 M), it was found that the capturing process happen in a fast reaction system with a second-order reaction kinetics of DBN/MDEA and first order with CO2. In addition, CO2 absorption was achieved using gas – liquid contact system. CO2 absorption rate was (2×10^(-5)-2.8 × 10^(-5) kmol⁄m^2 .sec) at DBN concentration (2 – 2.9 M). Finally, it is known that DBN/MDEA/1-Pentanol/CO2 system is easily switchable and can be used both CO2 capture and for other applications that require rapid change of medium from nonionic to ionic liquid.

scholarly journals Swelling of polyacrylamide-based hydrogel in aqueous solutions of low-molecular salts

2020 ◽  
Vol 64 (3) ◽  
pp. 293-299
Author(s):  
E. V. Vorobieva
Keyword(s):  
Sodium Chloride ◽  
Potassium Chloride ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
External Solution ◽  
Swelling Kinetics ◽  
Polymer Gel ◽  
Molecular Salts ◽  
Gel Phase ◽  
Kinetics Of

The swelling kinetics of cross-linked polyacrylamide was studied depending on the composition of the external solution. It was shown that the polymer gel swelling during the transition from water to a potassium or sodium chloride solution and vice versa sharply decreases, then gradually increases. The swelling of gel in a solution of sodium chloride is higher than that of potassium chloride. In the equilibrium swollen gel, the concentration of salts in the gel phase is higher than in the external solution and increases with the transition from potassium chloride to sodium chloride.

Kinetics of glucose transport in rat muscle: effects of insulin and contractions

1987 ◽  
Vol 253 (1) ◽  
pp. E12-E20 ◽  
Author(s):  
T. Ploug ◽  
H. Galbo ◽  
J. Vinten ◽  
M. Jorgensen ◽  
E. A. Richter
Keyword(s):  
Glucose Transport ◽  
Fiber Type ◽  
Fiber Types ◽  
Simple Diffusion ◽  
Glycogen Repletion ◽  
Gastrocnemius Muscles ◽  
Slow Twitch Fibers ◽  
Fast Twitch ◽  
Kinetics Of ◽  
Red And White Muscles

The effects of insulin and prior muscle contractions, respectively, on 3-O-methylglucose (3-O-MG) transport in skeletal muscle were studied in the perfused rat hindquarter. Initial rates of entry of 3-O-MG in red gastrocnemius, soleus, and white gastrocnemius muscles as a function of perfusate 3-O-MG concentration exhibited Michaelis-Menten kinetics. Uptake by simple diffusion could not be detected. The maximum 3-O-MG transport velocity (Vmax) was increased more by maximum isometric contractions (10- to 40-fold, depending on fiber type) than by insulin (20,000 microU/ml; 3- to 20-fold) in both red and white muscles. The effects of both contractions and insulin were greater in red than in white muscles. In red but not in white muscles, maximum increases in Vmax elicited by contractions and by insulin were additive. Both insulin and contractions decreased the half-saturating substrate concentration for glucose transport (apparent Km) in all three muscles, in fast-twitch fibers from 70 to approximately 7 mM and in slow-twitch fibers from 12 to 7 mM. After contractions, reversal of contraction-induced glucose transport was monoexponential in red fibers, with a half-time of 7 and 15 min in slow- and fast-twitch fibers, respectively. In white muscle, Vmax continued to increase after contractions, reached a plateau after 10 min, and had only decreased 45% after 70 min. In contrast to the prevailing opinion, in all fiber types, reversal of contraction-induced glucose transport took place in the absence of muscle glycogen repletion.

Effects of pH, Ca, ADH, and theophylline on kinetics of Na entry in frog skin

1978 ◽  
Vol 235 (1) ◽  
pp. C35-C48 ◽  
Author(s):  
L. J. Mandel
Keyword(s):  
Short Circuit ◽  
External Solution ◽  
Short Circuit Current ◽  
Electrochemical Gradient ◽  
Experimental Conditions ◽  
Entry Barrier ◽  
Different Types ◽  
Effects Of Ph ◽  
Kinetics Of ◽  
External Ph

The short circuit current as a function of Na concentration in both solutions was found to obey Michaelis-Menten kinetics under a variety of experimental conditions. Values of maximal transport rate (Im) and half-maximal Na concentrations (Kt) were determined from these experiments. Three type of results were obtained: 1) Im and Kt both decreased by approximately the same fraction when the pH of both solutions was reduced by increasing PCO2, 2) Im decreased and Kt increased when the external pH was decreased, and 3) Im increased with ADH and theophylline, decreased with external Ca, and Kt remained unchanged. Various criteria were utilized to determine that these were properties of the entry barrier for Na into the "transport pool." The results are explained in terms of a model that separates three different types of actions on the entry barrier: 1) competition of Na with other ions in the external solution for entry, 2) modulation of the number of sites available for Na translocation by changing the cytoplasmic pH, and 3) alterations in the rate of Na translocation caused by changes in the Na permeability or the electrochemical gradient across the entry barrier.

The Absorption of Sodium Ions by the Crayfish Astacus Pallipes Lereboullet

1960 ◽  
Vol 37 (3) ◽  
pp. 548-556
Author(s):  
J. SHAW
Keyword(s):  
Loss Rate ◽  
External Solution ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Ammonium Ions ◽  
External Concentration ◽  
Sodium Influx ◽  
Hydrogen Ion Concentration ◽  
Sodium Loss ◽  
Ammonium Compounds

1. The effect of various cations in the external solution on the sodium influx in the crayfish, Astacus pallipes, has been studied. 2. Potassium in concentrations up to 4 mM./l. has no significant effect on the sodium influx from 0.05 mM./l. NaCl solutions. 3. Calcium has no effect on the influx in concentrations up to 1 mM./l. At higher concentrations the influx may be reduced in some cases. 4. Magnesium generally increases the influx by about 30%. The effect is not related to the external concentration. 5. Ammonium ions reduce sodium influx. With an ammonium/sodium concentraton ratio of 20:1 the influx is reduced to about 20% of normal. Ammonium ions do not affect the sodium loss rate. 6. Simple substituted ammonium compounds have little effect on the influx. 7. The external hydrogen ion concentration reduces sodium influx if the pH is below 6. At pH 4 the influx is reduced to 20-30% of normal. A low pH does not decrease the rate of sodium loss. 8. The nature of the specific inhibition of sodium influx by ammonium ions is discussed. It is suggested that the ammonium ions interfere with a normal sodium ammonium exchange mechanism.

Sign in / Sign up

Export Citation Format

Share Document