THE POTASSIUM UPTAKE OF LACTOBACILLUS ACIDOPHILUS

SUMMARY: A reproducible flame speetrophotometric method for the determination of the potassium uptake of Lactobacilius acidophilus is described. The potassium uptake curve was characteristic and had a coefficient of variation between replicate samples at peak uptake of approximately 2%. Two general applications of the technique have been demonstrated: the evaluation of the toxicity of an inhibitory substance (fluoride as sodium fluoride), and determination of the effect of the interaction of L. acidophilus and L. casei in a mixed culture.     

THE IMPORTANCE OF POTASSIUM AFTER OPERATION

A deficiency of potassium in a patient after operation is manifest clinically by anorexia, malaise, apathy, weakness, abdominal distention and hypochloremia.Many patients who have had a prolonged disturbance in nutrition may have a “subclinical” hypopotassemia.Prophylaxis by means of replacement of the potassium excreted daily in the urine is the ideal treatment.When the clinical picture of potassium deficit develops, the amount of the potassium ion needed for replacement should be calculated on the basis of the total amount of water in the body of the patient.     

EFFECTS OF POTASSIUM ON THE POTENTIAL OF HALICYSTIS

Sea water in which sodium has been replaced by potassium produces about the same degree of negativity in Halicystis and in Valonia. With increasing dilution of this sea water up to 1 ÷ 16 the degree of negativity steadily falls off in Halicystis. This differs from the situation in Valonia where Damon finds that with increasing dilution the negativity passes through a minimum after which increasing dilution produces increasing negativity. But conditions in the two organisms differ so greatly that a comparison is of rather doubtful significance.     

THE ACTION OF POTASSIUM CYANIDE AND POTASSIUM FERRICYANIDE ON CERTAIN RESPIRATORY PIGMENTS

The oxygen in hemoglobin is liberated by K₃Fe(CN)₆ and not by KCN, that in hemocyanin by KCN and not by K₃Fe(CN)₆, that in hemerythrin by both, and that in echinochrome by K₃Fe(CN)₆ and not by KCN. The bearing of these results on the nature of the substances involved is discussed.     

THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS : III. THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE RETENTION OF POTASSIUM.

By perfusing frogs for varying periods with potassium-free Ringer solutions having a pH ranging from 6.0 to 8.0, it has been determined that such solutions have little or no effect upon the retention of potassium by muscle cells.     

SOME CHEMICAL ASPECTS OF THE POTASSIUM EFFECT

The ability of Nitella to distinguish electrically between Na⁺ and K⁺ (potassium effect) appears to depend on several organic substances (or groups of substances). Of these R_MK and R_SK determine the mobility and partition coefficient (S) respectively of K⁺ while R_MNa and R_SNa do the same for Na⁺. These substances can vary independently and this variation is susceptible to experimental control.     

MECHANICAL RESTORATION OF IRRITABILITY AND OF THE POTASSIUM EFFECT

Treatment of Nitella with distilled water apparently removes from the cell something which is responsible for the normal irritability and the potassium effect, (i.e. the large P.D. between a spot in contact with 0.01 M KCl and one in contact with 0.01 M NaCl). Presumably this substance (called R) is partially removed from the protoplasm by the distilled water. When this has happened a pinch which forces sap out into the protoplasm can restore its normal behavior. The treatment with distilled water which removes the potassium effect from the outer protoplasmic surface does not seem to affect the inner protoplasmic surface in the same way since the latter retains the outwardly directed potential which is apparently due to the potassium in the sap. But the inner surface appears to be affected in such fashion as to prevent the increase in its permeability which is necessary for the production of an action current. The pinch restores its normal behavior, presumably by forcing R from the sap into the protoplasm.     

THE RADIOACTIVITY OF POTASSIUM FROM HUMAN SOURCES

A comparison of the radioactivity of potassium from human and commercial sources indicates that the radioactive isotope K⁴⁰ is probably 1 or 2 per cent less abundant in human potassium.     

RESTORATION OF THE POTASSIUM EFFECT BY MEANS OF ACTION CURRENTS

Treatment with distilled water removes from Nitella the ability to give the large potential difference between 0.01 M KCl and 0.01 M NaCl which is known as the potassium effect. The potassium effect may be restored by action currents. This might be explained by saying that distilled water removes from the surface a substance, R, which is responsible for the potassium effect and which moves into the surface during the action current and thereby restores the potassium effect.     

钾抑制盐生植物生长的生理基础研究

盐生植物碱蓬中亚滨藜和补血草幼苗用不同浓度ＫＣｌ和等渗的ＮａＣｌ处理,结果表明,１００－５００和１００－４００ｍｍｏｌ／ＬＫＣｌ对它们的有面士重和净光合率产生明显抑制作用,证明Ｋ＾＋可抑制盐生植物生长并与光合速率降低有关。１００－４００ｍｍｏｌ／ＬＫＣｌ降低幼苗Ｎａ＾＋而增大Ｋ＾＋含量,对细胞渗透势和渗透调节能力基本不起作用,证明Ｋ＾＋抑制生长与植物体渗透调节物质Ｎａ＾＋不足以及高浓度的Ｋ＾＋对细     

THE RELATIONS OF TEMPERATURE TO THE POTASSIUM EFFECT AND THE BIOELECTRIC POTENTIAL OF VALONIA

The effect of temperature upon the bioelectric potential across the protoplasm of impaled Valonia cells is described. Over the ordinary tolerated range, the P.D. is lowest around 25°C., rising both toward 15° and 35°. The time curves are characteristic also. The magnitude of the temperature effect can be controlled by changing the KCl content of the sea water (normally 0.012 M): the magnitude is greatly reduced at 0.006 M KCl, enhanced at 0.024 M, and greatly exaggerated at 0.1 M KCl. Conversely, temperature controls the magnitude of the potassium effect, which is smallest at 25°, with a cusped time course. It is increased, with a smoothly rising course, at 15°, and considerably enhanced, with only a small cusp, at 35°. A temporary "alteration" of the protoplasmic surface by the potassium is suggested to account for the time courses. This alteration does not occur at 15°; the protoplasm recovers only slowly and incompletely at 25°, but rapidly at 35°, in such fashion as to make the P.D. more negative than at 15°. This would account for the temperature effects observed in ordinary sea water.     

POTASSIUM ACCUMULATION IN THE PROXIMAL CONVOLUTED TUBULES OF THE FROG'S KIDNEY

1. In a manner similar to that of the sartorius muscle, the isolated kidney of the frog can accumulate K against a gradient to upwards of three times its normal concentration. 2. The K-accumulating region is identified as the proximal tubule, which in the isolated tissue immersed over 24 hours in the cold (2–3°C.) amounts to about 90 per cent of the nephron minus the glomerulus. In the fresh tissue it constitutes about 70 per cent. The cells of the proximal tubule are impermeable to Na, but freely permeable to K and Cl. 3. The distal tubule in the isolated kidney does not accumulate K over the external concentration. The cells are permeable to Na which they actively extrude. This extrusion of Na goes parallel with a loss of osmotically associated water amounting to about 15 per cent of the weight of the fresh kidney, but varying somewhat with the conditions. 4. The accumulation of K in the proximal tubules is in accordance with the equations established for the sartorius muscle, and, as theoretically expected, there is no volume increase (but rather a small decrease) with the large accumulations, when the external Na concentration is maintained throughout. 5. With K accumulation in isotonic mixtures large volume changes occur as K is progressively substituted for Na. Over the range of external K concentration of 10 to 100 mM per litre the weight of the whole kidney changes to 2.5 times and the water of the cells of the proximal tubules increases to over four times. Up to an external K value of 90 mM per litre the mean weight of the kidney shows a linear relation when plotted against the reciprocal of the Na concentration plus the small glucose and Ca concentration. This relation is interpreted theoretically. 6. The effect of cyanide in the isotonic mixtures is to prevent the contraction of the distal tubules and to cause swelling of the same. It does not affect the volume, volume changes, or differential permeability of the proximal tubule. At the same time the membranes of the proximal tubule cells lose their characteristic permeability at a lower level of distension in the presence of cyanide. 7. The mean Na ratio for the kidney after 24 hours'' immersion in the cold is 0.26 ± 0.014 (giving standard deviation of mean). The ratio is defined as See PDF for Equation. For the fresh kidney the mean ratio is 0.39 ± 0.006. 8. The mean inulin ratio (28 observed in the cold) is 0.23 ± 0.012 and the same value for 10 observed at room temperature. At room temperature—2 hour immersion—the ratio is increased by cyanide to a mean of 0.32 ± 0.028, but only a slight increase is caused by cyanide in the cold. 9. The mean hemoglobin ratio after 24 hours'' immersion in the cold is 0.17 ± 0.004 and is unaffected by cyanide.