Potassium uptake

N. Claas.sen, K. M. Syring, and A. Jungk, Verification of a mathematical model by. simulating potassium uptake from soil. Plant Soil. 95 209 (1986). 

Dobermann A, Santa Cruz PC, Cassman KG. 1996. Fertilizer inputs, nutrient balance, and soil nutrient-supplying power in intensive, irrigated rice systems. I. Potassium uptake and K balance. Nutrient Cycling in Agroecosystems 46 1-10. 

Figure 3. Crop Response to Weed Presence, left, and Relative Potassium Uptake, right. Closeness of the vertical lines indicates the relative possibility of competition for K being a factor in crop yield reduction.

Il.f.l.1. Insulins. Insulin is the most effective of diabetes medications. Insulin has profound effects on carbohydrate, protein, fat metabolism and electrolytes. It has anabolic and anticatabolic actions. In a state of insulin deficiency, glycogenesis, glucose transport, protein synthesis, triglyceride synthesis, LPL activity in adipose tissue, cellular potassium uptake all decrease on the other hand, gluconeogene-sis, glycogenolysis, protein degradation, ketogene-sis, lipolysis increase. 

Havlin and Westfall (1985) found that the power-function equation described potassium release from soils well. The a and k values were highly correlated with nonexchangeable potassium release. They found that k from Eq. (2.53) was highly correlated with potassium uptake and the relative yield of alfalfa (Medicago sativa L.) as shown in Fig. 2.8. 

Srivastava, A., Pines, M., and Jacoby, B., 1989, Enhanced potassium uptake and phosphatidylinositol-phosphate turnover by hypertonic mannitol shock. Physiol. Plant 11 320-325. 

Relatively high concentrations of certain nutrients can also increase the uptake of other elements. For example, NH4 and sodium enhance potassium uptake magnesium and manganese enhance uptake of one another calcium enhances potassium uptake and zinc enhances uptake of both magnesium and manganese (Larcher, 1995). It is clear that the stoichiometry of elements available in soil solution can substantially decouple the stoichiometry of plant uptake from supply. 

The hydrated thallous ion is similar in size to the hydrated potassium ion, and early literature reported that the uptake of T1 cations in muscle cells made use of the specific uptake mechanism developed for potassium. However, later studies, taking account of the complexity of potassium transport, and the different types of potassium channels, have found some differences between the cellular T1 uptake and the potassium uptake. Thus, digoxin that inhibits the Na/K ATP-ase enzyme system as well as the potassium ion-transport, did not affect the ° T1 transport. 

Severe symptomatic hypokalemia was thought to have resulted from increased intracellular potassium uptake linked to massive leukocytosis after GM-CSF (15). 

Hyperkalemia P2-Agonists Promote cellular potassium uptake Salbutamol,Terbutaline... 

Inhibition of growth rate3 e.g., elongation of stem in Picea, Phaseolus, Pisum, of mesocotyl in Avena, of hypocotyl in Sinapis Sucrose uptake in epicotyles of Pisum Acetate uptake in roots of Phaseolus Potassium uptake in Pisum Enzyme activity (e.g., ATPase) in Phaseolus... 

Carels, M. and Shepherd, D. 1979. The effect of changes in pH on phosphate and potassium uptake by Monascus rubiginosus ATCC 16367 in submerged shaken culture. Can. J. Microbiol. 25(12), 1484-1488. 

Bioavailability of thallium, mainly a monovalent cation, is low. A thallium tolerance has been described (Sensfuss et al. 1986), and this is based on the mutation of a potassium uptake system, though a bacterium faces very unlikely toxic thallium concentrations. 

Muscle represents the largest tissue storage site, and contains -75% of intracellular potassium. Potassium uptake into skeletal muscle is affected by hormones, and is involved in the regulation of plasma potassium concentrations. A small amount of potassium can be found in the liver, and is reactively exchangeable. A similar amount of potassium is located in the red blood cells. The amount of potassium in bones is related to fresh matter similar to that in liver and red blood cells, but is not reactively exchangeable (Peterson 1997). 

On soils with a poor potassium status, the occurrence of potassium deficiency depends greatly on the crop that is being grown. Grasses, for instance, have a much greater potassium uptake capacity than lucerne or dover owing to their ramified, finely distributed root systems. Potassium ions owe their importance to their capadty to affect the water volume of plasma proteins, by controlling their water content and their influence on enzymes. 

Increases in plasma potassium are sufficient to stimulate insulin release into the portal circulation (DeFronzo 1992). Insulin stimulates potassium uptake by the liver... 

Claassen, N., Syring, K.M., Jungk, A., 1986. Verification of a mathematical model hy simulating potassium uptake from sod. Plant Soil 95, 209-220. 

The catalysts prepared with La surprisingly contained a higher amount of K than those prepared without La. We suggest that La enhances potassium uptake as the catalyst forms, because part of the La precipitates as a mixed potassium lanthanum carbonate, i.e. KLa(C03)2. A similar compound has been reported for sodium in the literature. A second important observauon is that the presence of both La and K in the catalyst does not necessarily induce a high selectivity, unless KOH is also employed in the basic I COs solution. Omission of KOH from the basic solution results in a similar chemical composition (compare cases two and four in Table 1.2) but a much less selective catalyst This is most likely a consequence of the precipitation procedure itself, tithout KOH in the base, a step-wise precipitation... 

Potassium is accumulated within cells by the action of the Na. K -ATPase (sodium pump) in which it participates in exchange for sodium that is extruded from the cell during potassium uptake [10]. Potassium has a major function as a carrier of charge within cells [1]. It is extremely mobile and therefore if it is allowed to pass through membranes it may be used to regulate potentials across cells, especially excitable cells such as muscle and nerve [16]. The regulation of such metal ion flows, especially of potassium and sodium, is crucial to life and is most clearly exemplified by the ionic movements that occur in nerve cells during excitation and transmission of the action potential [17]. 

The physiological effects of FC are manifold and well documented [16]. Most, if not all of them can be seen in conjunction with the marked acidification of the extracellular space and the hyperpolarization of the membrane potential observed almost immediately after addition of the toxin [16]. Drastic changes in solute transport across the plasma membrane occur (e.g. the potassium uptake by guard cells is stimulated [11]) concomitant with (as a consequence of ) the FC-induced increase in proton motive force. High-affinity FC-binding sites were characterized several years ago [for review see 2] in membranes from a number of plants, but purification of the sites proved impossible. As a consequence perhaps, interest in the binding sites faded after 1982, but has now resumed in several laboratories and this has resulted in the recent identification of the presumptive binding protein as well as its partial purification. 

Sacco S, Maffei M (1997) The effect of isosakuranetin (5,7-dihydroxy 4 -methoxy flava-none) on potassium uptake in wheat root segments. Phytochtanistry 46 245... 

Glass ADM (1974) Influence of phenolic acids on ion uptake. 111. Inhibition of potassium uptake. J Exp Bot 25 1104-1113... 

Fischer,R. A. Stomatal opening role of potassium uptake by guard cells. Science 160,18A-785 (1968)... 

This little story is mainly about my associations with potassium and rubidium, two elements in the alkali metal series of the periodic table. My Ph.D. thesis at the University of California in Berkeley (1934-1937) was concerned with potassium metabolism in the rat during pregnancy and lactation. In those days nutrition research was the major activity in biochemistry in the United States. In the course of my work I found among other things that the essential element, potassium, could be replaced by rubidium for growth of the rat, although after a time nervous disturbances and other toxic manifestations resulted. Rubidium is, in fact, transported by the same system which tissues use to take up potassium, so that nowadays one often measures potassium uptake activity with the radioactive isotope, Rb. The rubidium isotope happens to have a longer half-life and is more convenient to use than... 

In March of 19751 began a 6 months sabbatical at the Imperial Cancer Research Fund Laboratories in London. Michael Stoker suggested that I might work with Henry Rozen-gurt because of a common interest in active transport problems. We began a study of potassium uptake (measured by means of the more convenient competitive inhibitor, Rb) into cultured fibroblasts. The background for this problem was as follows ... 

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