Influence of dietary potassium on the absorption of magnesium from herbage and dry diets by ruminants

1998 ◽  
Vol 1998 ◽  
pp. 219-219
Author(s):  
O. Adediji ◽  
N.F. Suttle
Keyword(s):  
Inhibitory Effect ◽  
Extensive Review ◽  
Apparent Absorption ◽  
Marked Inhibitory Effect ◽  
Dietary Potassium ◽  
Dietary Magnesium ◽  
Sources Of Variation ◽  
Fractional Efficiency ◽  
K Concentration ◽  
Dry Diet

A recent extensive review of the ‘bioavailability’ of magnesium (Mg) (Henry and Benz 1995) noted that the fractional efficiency of apparent absorption of Mg (AAMg) in ruminants could vary from -0.04 to +0.66. Little attempt was made to identify sources of variation, other than those between inorganic Mg supplements. Earlier, ARC (1980) had failed to find consistent differences between fresh herbage (FH) and dry diets but a reexamination of the literature suggested that AAMg was twice as high for mixtures of roughage and concentrate (R/C) as for FH and confirmed the marked inhibitory effect of dietary potassium (K) (Suttle, 1987). Since grass is usually richer in K than a dry diet, differences between diet types in AAMg may be largely attributable to differences in K concentration. The objective of the study was to identify systematic sources of variation in the absorbability of dietary magnesium (Mg) to sheep from published balance studies.

Influence of dietary potassium on the absorption of magnesium from herbage and dry diets by ruminants

1998 ◽  
Vol 1998 ◽  
pp. 219-219 ◽  
Author(s):  
O. Adediji ◽  
N.F. Suttle
Keyword(s):  
Inhibitory Effect ◽  
Extensive Review ◽  
Apparent Absorption ◽  
Marked Inhibitory Effect ◽  
Dietary Potassium ◽  
Dietary Magnesium ◽  
Sources Of Variation ◽  
Fractional Efficiency ◽  
K Concentration ◽  
Dry Diet

A recent extensive review of the ‘bioavailability’ of magnesium (Mg) (Henry and Benz 1995) noted that the fractional efficiency of apparent absorption of Mg (AAMg) in ruminants could vary from -0.04 to +0.66. Little attempt was made to identify sources of variation, other than those between inorganic Mg supplements. Earlier, ARC (1980) had failed to find consistent differences between fresh herbage (FH) and dry diets but a reexamination of the literature suggested that AAMg was twice as high for mixtures of roughage and concentrate (R/C) as for FH and confirmed the marked inhibitory effect of dietary potassium (K) (Suttle, 1987). Since grass is usually richer in K than a dry diet, differences between diet types in AAMg may be largely attributable to differences in K concentration. The objective of the study was to identify systematic sources of variation in the absorbability of dietary magnesium (Mg) to sheep from published balance studies.

scholarly journals Quantifying the dietary potassium requirement of juvenile hybrid tilapia (Oreochromis niloticus×O. aureus)

2001 ◽  
Vol 85 (2) ◽  
pp. 213-218 ◽  
Author(s):  
Shi-Yen Shiau ◽  
Jia-Fen Hsieh
Keyword(s):  
Weight Gain ◽  
Atpase Activity ◽  
Oreochromis Niloticus ◽  
Polynomial Regression ◽  
Control Diet ◽  
Mean Value ◽  
Whole Body ◽  
Feeding Trial ◽  
Dietary Potassium ◽  
K Concentration

An 8 week feeding trial was conducted to determine the dietary K requirement for juvenile hybrid tilapia (Oreochromis niloticus × O. aureus). Purified diets with eight levels (0, 1, 2, 3, 4, 5, 7, 10 g/kg diet) of supplemental K were fed to tilapia. Each diet was fed to three replicate groups of fish initially weighing a mean value of 0.77 (SE 0.01) g/fish in a closed, recirculating rearing system. Weight gain was higher (P<0.05) in fish fed the diets supplemented with 2, 3 and 4 g K/kg diet than in fish fed diet with 10 g K/kg diet and the unsupplemented control diet. Gill Na+-K+ ATPase activity was highest in fish fed the diets supplemented with 1–3 g K/kg diet, followed by fish fed the diet with 5 g K/kg diet and lowest in fish fed the diet with 10 g K/kg diet. Whole-body K content in fish were generally increased as the dietary K supplementation level increased. Analysis by polynomial regression of weight gain and gill Na+-K+ ATPase activity and by linear regression of whole-body K retention of the fish indicated that the adequate dietary K concentration for tilapia is about 2–3 g/kg diet.

K+ transport across the lamprey erythrocyte membrane: characteristics of a Ba(2+)- and amiloride-sensitive pathway

1991 ◽  
Vol 159 (1) ◽  
pp. 303-324 ◽  
Author(s):  
K. Kirk
Keyword(s):  
Membrane Potential ◽  
Erythrocyte Membrane ◽  
Inhibitory Effect ◽  
Extracellular Ph ◽  
Transport Pathway ◽  
Full Effect ◽  
River Lamprey ◽  
K Concentration ◽  
86Rb Influx ◽  
K Transport

The characteristics of K+ transport in erythrocytes from the river lamprey (Lampetra fluviatilis) were investigated using standard radioisotope flux techniques. The cells were shown to have a ouabain-sensitive transport pathway that carried 43K+ and 86Rb+ into the cell at similar rates. Most of the ouabain-resistant 43K+ and 86Rb+ influx was via a pathway that was insensitive to cotransport inhibitors and to the replacement of extracellular Cl- or Na+. This pathway showed a strong selectivity for 43K+ over 86Rb+. It was inhibited fully by Ba2+ (I50 approximately 2.8 mumol l-1), amiloride (I50 approximately 150 mumol l-1) and ethylisopropylamiloride (I50 approximately 3.3 mumol l-1) and less effectively by quinine and by the tetraethylammonium ion. Inhibition by Ba2+ took full effect within a few minutes whereas the full inhibitory effect of amiloride took more than 1 h to develop. Experiments with the membrane potential probe [14C]tetraphenylphosphonium ion gave results consistent with the lamprey erythrocyte membrane having a Ba(2+)-sensitive K+ conductance that was significantly greater than the membrane Na+ conductance and which gave rise to a marked dependence of the membrane potential on the extracellular K+ concentration. The rate constants for Ba(2+)-sensitive 43K+ and 86Rb+ influx decreased (proportionally) with increasing extracellular K+ concentration in a manner that was consistent with the transport being via a conductive pathway. The decrease was attributed to a depolarisation of the membrane (in response to the increasing extracellular K+ concentration) and a consequent decrease in the driving force for the conductive movement of 43K+ and 86Rb+ into the cells. Ba(2+)-sensitive 86Rb+ influx increased significantly with decreasing cell volume and with increasing intracellular pH (at a constant extracellular pH) but increased only slightly with increasing extracellular pH. The pathway operated normally in the complete absence of extracellular Ca2+ but its activity decreased in cells pretreated with ionomycin and EGTA; this suggests a role for intracellular Ca2+ in the operation of the pathway.

The Histidine Requirement of a Normal and a Leukaemia Cell-Line from Man: Comparative Effects on Cell Growth, Metabolism and Composition

1974 ◽  
Vol 15 (2) ◽  
pp. 407-417
Author(s):  
J. B. GRIFFITHS
Keyword(s):  
Cell Growth ◽  
Protein Composition ◽  
Inhibitory Effect ◽  
Leukaemia Cell ◽  
Leukaemia Cell Line ◽  
Marked Inhibitory Effect ◽  
Normal Human ◽  
Therapeutic Enzymes ◽  
Therapy Studies ◽  
Human Leukaemia

The object was to determine whether the depletion of histidine would have a more marked inhibitory effect on human leukaemia cells than on normal human cells, thus indicating a wider use for enzymes in cancer therapy. Studies of the effect of histidine concentration on cell growth, death, metabolism, protein composition, histidine uptake and utilization by cells were carried out. The medium and intracellular concentrations of histidine required for optimum cell growth and metabolism were much lower than for any other amino acid that has been studied. Also, there was very little evidence of cell death occurring in the absence of histidine. The results showed that cells in culture have a very low histidine requirement and that although the leukaemia cells were slightly more dependent upon histidine than normal cells the effect of histidine depletion is not critical enough to show much promise as a method of controlling leukaemia by therapeutic enzymes.

Inhibition of granulocyte phagocytosis of Candida albicans by amphotericin B

1978 ◽  
Vol 24 (4) ◽  
pp. 363-364 ◽  
Author(s):  
C. K. Chan ◽  
Edward Balish
Keyword(s):  
Candida Albicans ◽  
Amphotericin B ◽  
Phagocytic Activity ◽  
Inhibitory Effect ◽  
Marked Inhibitory Effect

Phagocytic activity of PMN's in five healthy and five burned patients were measured in vitro. Addition of 1 μg per millilitre of amphotericin B to the assay produced a marked inhibitory effect of the phagocytic activity of PMN against C. albicans.

Effect of dietary K+ and 75% nephrectomy on the morphology of principal cells in CCDs

1989 ◽  
Vol 256 (3) ◽  
pp. F387-F396
Author(s):  
R. K. Zalups
Keyword(s):  
Surface Density ◽  
Renal Mass ◽  
Basolateral Membrane ◽  
Inhibitory Effect ◽  
Potassium Depletion ◽  
Large Reduction ◽  
Factors Associated ◽  
Principal Cells ◽  
Marked Inhibitory Effect ◽  
Collecting Ducts

This investigation was carried out to determine the effect of potassium on the amplification of the basolateral membrane of principal cells in cortical collecting ducts (CCDs), which normally occurs after a large reduction of renal mass. Rats that underwent a 75% reduction of renal mass and were fed a diet deficient in potassium for 10 days after surgery had a lower concentration of potassium in the blood and excreted less potassium in the urine than either corresponding sham-operated (SO) rats or 75% nephrectomized (NPX) rats fed a normal-potassium diet. In the NPX rats fed the diet deficient in potassium, there was a marked inhibitory effect on the amplification of the basolateral membrane, which normally occurs in principal cells of CCDs after renal mass has been greatly reduced. In fact the surface density of the basolateral membrane, as well as the size of the principal cells in the animals fed the diet deficient in potassium were the same as those of principal cells in the SO rats fed the normal-potassium diet. Thus the present data show that the increase in cell size and the amplification of the basolateral membrane that occurs in principal cells after a 75% reduction of renal mass is inhibited by factors associated with potassium depletion.

Calcium in the control of renin secretion: Ca2+ influx as an inhibitory signal

1981 ◽  
Vol 240 (1) ◽  
pp. F70-F74 ◽  
Author(s):  
C. S. Park ◽  
D. S. Han ◽  
J. C. Fray
Keyword(s):  
Incubation Temperature ◽  
Inhibitory Effect ◽  
Renin Secretion ◽  
Juxtaglomerular Cells ◽  
Stimulatory Action ◽  
Inhibitory Signal ◽  
Ca Antagonist ◽  
K Concentration ◽  
Energy Dependent

The mechanism for the inhibition of renin secretion in vitro from renal cortical slices by angiotensin II, antidiuretic hormone, ouabain, and high K+ concentration was studied. The inhibitory effect of these agents was blocked by a Ca antagonist, verapamil. In addition, epinephrine stimulated renin secretion and its stimulatory action was blocked by ouabain. These results support the hypothesis that Ca2+ influx into juxtaglomerular cells plays a role as an inhibitory signal whereas Ca2+ efflux is a stimulatory signal for renin secretion. Renin secretion was greatly stimulated by lowering incubation temperature, indicating that renin secretion is not energy dependent. The possibility is discussed that Ca2+ of juxtaglomerular cells might activate an enzyme(s) that then modulates some sequential steps of renin secretory processes, thereby controlling the rate of renin secretion.

Kinetic Studies on Soluble and Insoluble Urokinases

1975 ◽  
Vol 53 (8) ◽  
pp. 890-894 ◽  
Author(s):  
F. C. Capet-Antonini ◽  
J. Tamenasse
Keyword(s):  
Methyl Ester ◽  
Kinetic Studies ◽  
Inhibitory Effect ◽  
Soluble Enzyme ◽  
Covalent Coupling ◽  
Ph Values ◽  
Marked Inhibitory Effect ◽  
Insoluble Form ◽  
Michaelis Constants

A water-insoluble urokinase (ins-UK) was prepared by covalent coupling to an electrostatically neutral polyacrylamide derivative. The esteratic activity retained by the bound enzyme is about 70% of that of the soluble urokinase (UK).Comparative kinetic studies of these two forms of the enzyme were undertaken on lysine esters: N-α-acetyl-L-lysine-methyl ester (ALMe) and N-α-acetylglycyl-L-lysine methyl ester (AGLMe). It was first observed that these substrates both exhibit a marked inhibitory effect toward soluble UK, whereas this phenomenon was less manifest with the insoluble form of the enzyme. Michaelis constants and maximal velocities measured at 33 °C, for UK and ins-UK, were identical when ALMe was used, but slightly different with AGLMe. Determination of initial velocities, at a series of pH values shows only minimal differences in the behavior of the soluble enzyme with respect to that of the insoluble form. However, over a range of temperatures, differing Km values for these two enzyme forms were obtained using AGLMe as the substrate. These last results suggest possible interactions between the substrate and the insoluble carrier of the enzyme.

An Antiproteolytic and Antifibrinolytic Preparation Obtained from the Potato by Means of Chromatography on SE-Sephadex C-50

1974 ◽  
Vol 32 (02/03) ◽  
pp. 617-632 ◽  
Author(s):  
K Worowski
Keyword(s):  
Enzyme Inhibitor ◽  
Inhibitory Effect ◽  
Marked Inhibitory Effect ◽  
Proteolytic Enzyme Inhibitor ◽  
Crude Preparation ◽  
Chemical Factors ◽  
Stepwise Gradient ◽  
C 50 ◽  
Physical And Chemical ◽  
Structure Of Proteins

SummaryA crude preparation of a proteolytic enzyme inhibitor from potatoes was purified by means of column chromatography with SE-Sephadex C-50 using a stepwise gradient of concentration and pH when eluting proteins from the column. The inhibitor preparation thus obtained is stable for a 28 day period of storage and resistant to the action of various physical and chemical factors harmful to the spatial structure of proteins. The potato protease inhibitor markedly inhibits the activity of trypsin, chymotrypsin, plasmin and alkaline proteases from Aspergillus flavus. The inhibition of pronase and a mixture of acid cellular proteases by this inhibitor is considerably less. Pepsin, cathepsin D, and collagenase are not affected by this inhibitor. The potato inhibitor has a marked inhibitory effect on plasmin fibrinolytic activity both in purified systems and in the plasma euglobulin fraction. It also protects the fibrinogen from the action of this enzyme. It does not, however, inhibit plasminogen activation under the influence of either streptokinase or urokinase.

scholarly journals A possible autocrine role for interleukin-6 in two lymphoma cell lines

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 798-804 ◽  
Author(s):  
C Yee ◽  
A Biondi ◽  
XH Wang ◽  
NN Iscove ◽  
J de Sousa ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Growth Factor ◽  
Cell Lines ◽  
Interleukin 6 ◽  
Inhibitory Effect ◽  
Lymphoma Cell ◽  
Hematopoietic Stem ◽  
Biologic Activity ◽  
Marked Inhibitory Effect

Abstract Interleukin-6 (IL-6) is a growth factor with diverse biologic activity. Originally described as a T-cell product that enhances immunoglobulin (Ig) secretion in antigen-stimulated B cells, it also affects the growth of T cells, plasmacytomas, hybridomas, and hematopoietic stem cells. We report the expression and secretion of IL-6 by two lymphoma cell lines, OCI-LY3 and OCI-LY12. Addition of recombinant IL-6 stimulated their growth, whereas addition of polyclonal anti- recombinant IL-6 (anti-rIL-6) had a marked inhibitory effect on proliferation. These results suggest an autocrine role for IL-6 in the growth of these lymphoma cells in culture.

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