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 THE KINETICS OF PENETRATION

1934 ◽  
Vol 17 (4) ◽  
pp. 507-516 ◽  
Author(s):  
W. J. V. Osterhout ◽  
S. E. Kamerling
Keyword(s):  
Aqueous Phase ◽  
Partition Coefficients ◽  
Organic Anion ◽  
External Solution ◽  
Living Cells ◽  
Approach To Equilibrium ◽  
Aqueous Layer ◽  
Pass Through ◽  
Kinetics Of ◽  
System Approaches

A model is described which throws light on the mechanism of accumulation. In the model used an external aqueous phase A is separated by a non-aqueous phase B (representing the protoplasm) from the artificial sap in C. A contains KOH and C contains HCl: they tend to mix by passing through the non-aqueous layer but much more KOH moves so that most of the KCl is formed in C, where the concentration of potassium becomes much greater than in A. This accumulation is only temporary for as the system approaches equilibrium the composition of A approaches identity with that of C, since all the substances present can pass through the non-aqueous layer. Such an approach to equilibrium may be compared to the death of the cell as the result of which accumulation disappears. During the earlier stages of the experiment potassium tends to go in as KOH and at the same time to go out as KCl. These opposing tendencies do not balance until the concentration of potassium inside becomes much greater than outside (hence potassium accumulates). The reason is that KCl, although its driving force be great, moves very slowly in B because its partition coefficient is low and in consequence its concentration gradient in B is small. This illustrates the importance of partition coefficients for penetration in models and in living cells. It also indicates that accumulation depends on the fact that permeability is greater for the ingoing compound of the accumulating substance than for the outgoing compound. Other things being equal, accumulation is increased by maintaining a low pH in C. Hence we may infer that anything which checks the production of acid in the living cell may be expected to check accumulation and growth. This model recalls the situation in Valonia and in most living cells where potassium accumulates as KCl, perhaps because it enters as KOH and forms KA in the sap (where A is an organic anion). In some plants potassium accumulates as KA but when HCl exists in the external solution it will tend to enter and displace the weaker acid HA (if this be carbonic it can readily escape): hence potassium may accumulate to a greater or less extent as KCl. Injury of the cell may produce a twofold effect, (1) increase of permeability, (2) lessened accumulation. The total amount of electrolyte taken up in a given time will be influenced by these factors and may be greater than normal in the injured cell or less, depending somewhat on the length of the interval of time chosen.

scholarly journals THE KINETICS OF PENETRATION

1933 ◽  
Vol 16 (3) ◽  
pp. 529-557 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Potassium Salt ◽  
Partition Coefficients ◽  
Living Cells ◽  
Constant Ratio ◽  
Ionic Activity ◽  
Activity Product ◽  
Exponential Decrease ◽  
Monomolecular Reactions ◽  
Aqueous Layer ◽  
Kinetics Of

An organic potassium salt, KG, passes from an aqueous phase, A, through a non-aqueous layer, B, into a watery solution, C. In C it reacts with CO2 to form KHCO3. The ionic activity product (K) (G) in C is thus kept at such a low level that KG continues to diffuse into C after the concentration of potassium becomes greater in C than in A. Hence potassium accumulates in C, the osmotic pressure rises, and water goes in. A steady state is eventually reached in which potassium and water enter C in a constant ratio. The rate of entrance of potassium (with no water penetrating into C) may fall off in a manner approximately exponential. But water enters and may produce an exponential decrease in concentration. This suggests that the kinetics may be treated like that of two consecutive monomolecular reactions. Calculations made on this basis agree very well with the observed values. The rate of penetration appears to be proportional to the concentration gradient of KG in the non-aqueous layer and in consequence depends upon the partition coefficients which determine this gradient. Exchange of ions (passing as such through the non-aqueous layer) does not seem to play an important rôle in the entrance of potassium. The kinetics of the model may be similar to that of living cells.

scholarly journals THE KINETICS OF PENETRATION

1932 ◽  
Vol 16 (1) ◽  
pp. 157-163 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Aqueous Solution ◽  
Steady State ◽  
Living Cell ◽  
External Solution ◽  
Living Cells ◽  
Similar Process ◽  
Alkaline Aqueous Solution ◽  
Solution Bathing ◽  
Aqueous Layer ◽  
Kinetics Of

In a model consisting of a non-aqueous layer (representing the protoplasm) placed between an inner, more acid, aqueous layer (representing the sap) and an outer, more alkaline, aqueous solution (representing the external solution bathing a living cell) the penetration of potassium creates an outwardly directed potential against which potassium continues to diffuse inward, thereby increasing the outward potential. This continues until the steady state is reached. The potassium sets up less potential in entering than in escaping and the net result is an outwardly directed potential. A similar process appears to take place in certain living cells.

Interphase distribution of 2-furylethylenes

1985 ◽  
Vol 50 (8) ◽  
pp. 1642-1647 ◽  
Author(s):  
Štefan Baláž ◽  
Anton Kuchár ◽  
Ernest Šturdík ◽  
Michal Rosenberg ◽  
Ladislav Štibrányi ◽  
...  
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Transport Rate ◽  
Phase System ◽  
Two Phase ◽  
Interphase Distribution ◽  
Distribution Kinetics ◽  
System 1 ◽  
Kinetics Of

The distribution kinetics of 35 2-furylethylene derivatives in two-phase system 1-octanol-water was investigated. The transport rate parameters in direction water-1-octanol (l1) and backwards (l2) are partition coefficient P = l1/l2 dependent according to equations l1 = logP - log(βP + 1) + const., l2 = -log(βP + 1) + const., const. = -5.600, β = 0.261. Importance of this finding for assesment of distribution of compounds under investigation in biosystems and also the suitability of the presented method for determination of partition coefficients are discussed.

scholarly journals THE ACCUMULATION OF ELECTROLYTES

1932 ◽  
Vol 15 (6) ◽  
pp. 667-689 ◽  
Author(s):  
W. J. V. Osterhout ◽  
W. M. Stanley
Keyword(s):  
Steady State ◽  
Osmotic Pressure ◽  
Aqueous Phase ◽  
Thermodynamic Potential ◽  
Ph Value ◽  
Molecular Form ◽  
External Solution ◽  
Aqueous Layer ◽  
The Difference ◽  
Pass Through

Inasmuch as attempts to explain accumulation by the Donnan principle have failed in the case of Valonia, a hypothesis of the steady state has been formulated to explain what occurs. In order to see whether this hypothesis is in harmony with physico-chemical laws attempts have been made to imitate its chief features by means of a model. The model consists of a non-aqueous layer (representing the protoplasmic surface) placed between an alkaline aqueous phase (representing the external solution) and a more acid aqueous phase (representing the cell sap). The model reproduces most of the features of the hypothesis. Attention may be called to the following points. 1. The semipermeable surface is a continuous non-aqueous phase. 2. Potassium penetrates by combining with an acid HX in the non-aqueous layer to form KX which in turn reacts with an acid HA in the sap to form KA. Since KX is little dissociated in the non-aqueous layer potassium appears to pass through it chiefly in molecular form. 3. The internal composition depends on permeability, e.g., sodium penetrates less rapidly than potassium and in consequence potassium predominates over sodium in the "artificial sap." The order of penetration in the model is the same as in Valonia, i.e., K > Na > Ca > Mg, and Cl > SO4, but the quantitative resemblance is not close, e.g., the difference between potassium and sodium, and chloride and sulfate is much less in the model. 4. The formation of KA and NaA in the sap raises its osmotic pressure and water enters. 5. The concentration of potassium and sodium and the osmotic pressure become much greater inside than outside. For example, potassium may become 200 times as concentrated inside as outside. 6. No equilibrium occurs but a steady state is reached in which water and salt enter at the same rate so that the composition of the sap remains constant as its volume increases. 7. Since no equilibrium occurs there is a difference of thermodynamic potential between inside and outside. At the start the thermodynamic potential of KOH is much greater outside than inside. This difference gradually diminishes and in the steady state has about the same value as in Valonia. The difference in pH value between the internal and external solutions is also similar in both cases (about 2 pH units). 8. Accumulation does not depend on the presence of molecules or ions inside which are unable to pass out. One important feature of the hypothesis is not seen in the model: this is the exchange of HCO3 for Cl-. Experiments on this point are in progress.

scholarly journals DIFFUSION POTENTIALS IN MODELS AND IN LIVING CELLS

1943 ◽  
Vol 26 (3) ◽  
pp. 293-307 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Living Cell ◽  
Partition Coefficients ◽  
Living Cells ◽  
Extended Form ◽  
Electrical Potentials ◽  
Ionic Mobilities ◽  
Diffusion Potentials

The behavior of guaiacol resembles that of certain protoplasmic surfaces to such an extent that it can be advantageously used in models designed to imitate certain aspects of protoplasmic behavior. In these models the electrical potentials appear to consist of diffusion potentials and this may be true of certain living cells. In dealing with models we determine ionic mobilities and use these to predict potentials. In studying living cells we measure potentials and from these calculate ionic mobilities. The question arises, how far is this method justified. To test this we have treated guaiacol like a living cell, measuring potentials and from these estimating ionic mobilities. The results Justify the use of this method. This is of interest because the method is most useful in studying protoplasmic activity. In its extended form it enables us to follow changes in mobilities and in partition coefficients due to applied reagents and to metabolism.

scholarly journals CALCULATIONS OF BIOELECTRIC POTENTIALS

1939 ◽  
Vol 23 (2) ◽  
pp. 171-176 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Partition Coefficient ◽  
Partition Coefficients ◽  
Alkali Metals ◽  
Ionic Radius ◽  
Chloride Ion ◽  
Sodium Ion ◽  
Potassium Ions ◽  
Aqueous Layer ◽  
Sodium And Potassium ◽  
Bioelectric Potentials

Values have been calculated for apparent mobilities and partition coefficients in the outer non-aqueous layer of the protoplasm of Nitella. Among the alkali metals (with the exception of cesium) the order of mobilities resembles that in water and the partition coefficients (except for cesium) follow the rule of Shedlovsky and Uhlig, according to which the partition coefficient increases with the ionic radius. Taking the mobility of the chloride ion as unity, we obtain the following: lithium 2.04, sodium 2.33, potassium 8.76, rubidium 8.76, cesium 1.72, ammonium 4.05, ½ magnesium 20.7, and ½ calcium 7.52. After exposure to guaiacol these values become: lithium 5.83, sodium 7.30, potassium 8.76, rubidium 8,76, cesium 3.38, ammonium 4.91, ½ magnesium 20.7, and ½ calcium 14.46. The partition coefficients of the chlorides are as follows, when that of potassium chloride is taken as unity: lithium 0.0133, sodium 0.0263, rubidium 1.0, cesium 0.0152, ammonium 0.0182, magnesium 0.0017, and calcium 0.02. These are raised by guaiacol to the following: lithium 0.149, sodium 0.426, rubidium 1.0, cesium 0.82, ammonium 0.935, magnesium 0.0263, and calcium 0.323 (that of potassium is not changed). The effect of guaiacol on the mobilities of the sodium and potassium ions resembles that seen in Halicystis but differs from that found in Valonia where guaiacol increases the mobility of the sodium ion but decreases that of the potassium ion.

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 CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM

1939 ◽  
Vol 22 (3) ◽  
pp. 417-427 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Partition Coefficient ◽  
Action Current ◽  
Protoplasmic Surface ◽  
Outer Protoplasmic Surface ◽  
Ionic Mobilities

In Nitella, as in Halicystis, guaiacol increases the mobility of Na+ in the outer protoplasmic surface but leaves the mobility of K+ unaffected. This differs from the situation in Valonia where the mobility of Na+ is increased and that of K+ is decreased. The partition coefficient of Na+ in the outer protoplasmic surface is increased and that of K+ left unchanged. Recovery after the action current is delayed in the presence of guaiacol and the action curves are "square topped."

scholarly journals THE KINETICS OF PENETRATION

1934 ◽  
Vol 18 (2) ◽  
pp. 229-234 ◽  
Author(s):  
S. E. Kamerling ◽  
W. J. V. Osterhout
Keyword(s):  
Osmotic Pressure ◽  
Living Cell ◽  
External Solution ◽  
Aqueous Layer ◽  
Kinetics Of

To imitate cells which have ceased to grow we have made models in which artificial sap is separated from the external solution by a non-aqueous layer (representing the protoplasm). A stream of CO2 is bubbled through the artificial sap to imitate its production by the living cell. Potassium passes from the external solution through the non-aqueous layer into the artificial sap and there reacts with CO2 to form KHCO3: its rate of entrance depends on the supply of CO2. Hence the increase of volume depends on the supply of CO2 (as is probably true of the living cell). By regulating the supply of CO2 and the osmotic pressure we are able to keep the volume and composition of the artificial sap approximately constant while maintaining a higher concentration of potassium than in the external solution. In these respects the model resembles certain mature cells which have ceased to grow.

Sign in / Sign up

Export Citation Format

Share Document