Insulin does not act by causing a change in membrane potential or intracellular free sodium and potassium concentration of adipocytes

Diabetes ◽  
1980 ◽  
Vol 29 (12) ◽  
pp. 1040-1043 ◽  
Author(s):  
R. J. Stark ◽  
P. D. Read ◽  
J. O'Doherty
Keyword(s):  
Membrane Potential ◽  
Potassium Concentration ◽  
Sodium And Potassium

Sodium dependence of the thyrotrophin-induced depolarization in cultured porcine thyroid cells

1986 ◽  
Vol 108 (2) ◽  
pp. 225-230 ◽  
Author(s):  
T. A. Hambleton ◽  
J. R. Bourke ◽  
G. J. Huxham ◽  
S. W. Manley
Keyword(s):  
Membrane Potential ◽  
Action Potentials ◽  
Potassium Concentration ◽  
Sodium Current ◽  
Resting Membrane Potential ◽  
Thyroid Cell ◽  
Free Medium ◽  
Thyroid Cells ◽  
Voltage Dependent ◽  
Sodium And Potassium

ABSTRACT Cultured porcine thyroid cells exhibit a resting membrane potential of about − 73 mV and depolarize to about − 54 mV on exposure to TSH. The depolarizing response to TSH was preserved in a medium consisting only of inorganic salts and buffers, but was abolished in sodium-free medium, demonstrating dependence on an inward sodium current. Increasing the potassium concentration of the medium resulted in a reduction in the resting membrane potential of 60 mV per tenfold change in potassium concentration, and a diminished TSH response. A hyperpolarizing TSH response was observed in a sodium- and bicarbonate-free medium, indicating that a hyperpolarizing ion current (probably carried by potassium) was also enhanced in the presence of TSH. Tetrodotoxin blocked the TSH response. We conclude that the response of the thyroid cell membrane to TSH involves increases in permeability to sodium and potassium, and that the thyroid membrane ion channels bear some similarity to the voltage-dependent sodium channels of excitable tissues, despite the absence of action potentials in the thyroid. J. Endocr. (1986) 108, 225–230

THE EFFECTS OF OESTROGEN AND PROGESTERONE ON THE SODIUM AND POTASSIUM CONCENTRATIONS OF RAT UTERINE FLUID

1970 ◽  
Vol 47 (3) ◽  
pp. 309-319 ◽  
Author(s):  
C. A. B. CLEMETSON ◽  
V. R. MALLIKARJUNESWARA ◽  
M. M. MOSHFEGHI ◽  
J. J. CARR ◽  
J. H. WILDS
Keyword(s):  
Membrane Potential ◽  
Potassium Concentration ◽  
Ovarian Hormones ◽  
Pronounced Change ◽  
Sodium Potassium ◽  
Delayed Implantation ◽  
Uterine Fluid ◽  
Sodium And Potassium

SUMMARY Studies of the electrolyte concentrations of uterine fluid samples from spayed rats, after injection of ovarian hormones, showed a much higher potassium concentration after treatment with oestrogen (42·3 m-equiv./1.) than with progesterone (20·8 m-equiv./1.). There was an even more pronounced change in the sodium: potassium ratio, which fell from 7·3 to 1 with progesterone to 2·5 to 1 with oestrogen. These findings are supported by recalculation of the results of Heap & Lamming (1962). It is suggested that these changes in the Na+ and K+ concentrations of uterine fluid produce changes in the membrane potential of the endometrium which could account for delayed implantation of the negatively charged blastocyst under progesterone dominance and implantation under oestrogen dominance.

scholarly journals Influence of Erythrocytes on Direct Potentiometric Determination of Sodium and Potassium

1983 ◽  
Vol 20 (2) ◽  
pp. 116-120 ◽  
Author(s):  
P Bijster ◽  
H L Vader ◽  
C L J Vink
Keyword(s):  
Whole Blood ◽  
Potassium Concentration ◽  
Reference Electrode ◽  
Sodium Concentration ◽  
General Phenomenon ◽  
Liquid Junction ◽  
Direct Potentiometry ◽  
The Difference ◽  
Sodium And Potassium

We have shown that the sodium concentration in whole blood measured by direct potentiometry is higher than in plasma. The ‘erythrocyte-effect’, already described by Siggaard Andersen, is most pronounced for instruments equipped with a reference electrode with an open static liquid junction and is thus a general phenomenon. Instruments with a modified liquid junction show less interference. The same phenomenon appears for the determination of the potassium concentration, although the difference between whole blood and plasma, when measured with instruments equipped with a modified liquid junction, can be neglected in practice.

scholarly journals The Ionic Basis of the Resting Potential in a Cross-Striated Muscle of the Aquatic Snail Lymnaea Stagnalis

1984 ◽  
Vol 108 (1) ◽  
pp. 305-314
Author(s):  
B. L. BREZDEN ◽  
D. R. GARDNER
Keyword(s):  
Membrane Potential ◽  
Lymnaea Stagnalis ◽  
Striated Muscle ◽  
Potassium Concentration ◽  
Muscle Cells ◽  
Resting Potential ◽  
Extracellular Potassium ◽  
Heart Ventricle ◽  
Sodium Permeability ◽  
Ionic Basis

The mean resting potential in the heart ventricle muscle cells of the freshwater snail Lymnaea stagnalis was found to be −61.2±3.5 (˙˙) mV (ranging from −56mV to −68mV). The average intracellular potassium concentration was estimated to be 51.5±14.6(˙˙) m (ranging from 27.8 m to 77.3 m). The membrane of the heart ventricle muscle cells appears to be permeable to both potassium and chloride, as changes in the extracellular concentration of either of these ions resulted in a change in the membrane potential. A ten-fold change in the extracellular potassium concentration was associated with a 50.4±3.8(˙˙) mV slope when the potassium concentration was above about 6 m. Deviations from the straight-line relation predicted for a potassium electrode could be accounted for by introducing a term for sodium permeability. The ionic basis of the membrane potential in these cells can be described by a modified form of the Goldman-Hodgkin- Katz equation.

Disorders of potassium homeostasis

2010 ◽  
pp. 3831-3845 ◽  
Author(s):  
J Firth
Keyword(s):  
Membrane Potential ◽  
Potassium Concentration ◽  
Resting Membrane Potential ◽  
Extracellular Potassium ◽  
Normal Range ◽  
Critical Determinant ◽  
Potassium Homeostasis ◽  
Extracellular Potassium Concentration

The normal range of potassium concentration in serum is 3.5 to 5.0 mmol/litre and within cells it is 150 to 160 mmol/litre, the ratio of intracellular to extracellular potassium concentration being a critical determinant of cellular resting membrane potential and thereby of the function of excitable tissues....

Inhibition of aldosterone-induced antinatriuresis and kaliuresis by actinomycin D

1984 ◽  
Vol 246 (2) ◽  
pp. F201-F204 ◽  
Author(s):  
J. D. Horisberger ◽  
J. Diezi
Keyword(s):  
Urinary Excretion ◽  
Intravenous Infusion ◽  
Sodium Excretion ◽  
Actinomycin D ◽  
Potassium Concentration ◽  
Plasma Potassium ◽  
Potassium Excretion ◽  
Short Term ◽  
Sodium And Potassium ◽  
Term Response

The effects of actinomycin D on short-term response to aldosterone on sodium and potassium urinary excretion were investigated in adrenalectomized glucocorticoid-substituted anesthetized rats. Aldosterone alone (1 microgram/kg followed by sustained intravenous infusion of 1 microgram X kg-1 X h-1) entailed a simultaneous antinatriuretic and kaliuretic effect after a latent period of 30-60 min. Actinomycin D (300 micrograms/kg) administered intravenously 30 min before aldosterone inhibited both the aldosterone-induced kaliuresis and antinatriuresis and the concomitant changes in plasma potassium concentration. The administration of actinomycin D alone enhanced sodium excretion in the first hour and then induced kaliuresis. These results favor the hypothesis that mineralocorticoid effects of aldosterone on sodium and potassium excretion are closely linked and may be dependent on the same mechanisms.

Acute effect of ACTH, aldosterone, sodium and potassium on parotid secretion

1959 ◽  
Vol 197 (3) ◽  
pp. 565-567 ◽  
Author(s):  
L. L. Langley ◽  
W. A. Beall ◽  
J. A. Smith
Keyword(s):  
Intravenous Infusion ◽  
Potassium Level ◽  
Potassium Concentration ◽  
Single Injection ◽  
Sodium Concentration ◽  
Acute Effect ◽  
Adrenal Steroids ◽  
Direct Influence ◽  
Parotid Saliva ◽  
Sodium And Potassium

The intravenous administration of 20 u of ACTH in a single injection alters the flow and composition of parotid saliva in the dog. The flow was increased 44%, sodium concentration 75% and the potassium concentration decreased 19%. These alterations do not occur in the adrenalectomized dog. Aldosterone increased the sodium concentration only 20%, decreased the potassium level 6.3% and had an insignificant influence on flow. The intravenous infusion of sodium decreases parotid flow whereas potassium increases it. It is concluded that these alterations represent a direct influence of the electrolytes on the gland since adrenalectomy has no influence on this response. It is suggested that parotid function is changed by the infusion of these electrolytes due to the alteration of the intra-extracellular gradients. The adrenal steroids may have a similar effect.

Na and K levels in blood and marrow cells of normal and phenylhydrazine-treated rabbits

1962 ◽  
Vol 203 (2) ◽  
pp. 283-285 ◽  
Author(s):  
James W. Archdeacon ◽  
Harold C. Rohrs
Keyword(s):  
Blood Cells ◽  
Bone Marrow Cells ◽  
Potassium Concentration ◽  
Plasma Potassium ◽  
Progressive Increase ◽  
Ionic Concentration ◽  
Normal Bone ◽  
Slight Rise ◽  
Sodium And Potassium ◽  
Marrow Cells

Sodium and potassium contents of marrow cells, blood cells, and plasma were measured in normal rabbits and rabbits injected subcutaneously with phenylhydrazine to determine if small quantities of this chemical affected the ability of the blood and marrow cells to maintain their normal levels of these ions. There was a decrease in potassium content of red blood cells within 24 hr after administration of the compound, followed subsequently by a slight rise in plasma potassium. Apparently any effect was closely related to the time of blood sampling after the last injection, recovery occurring within several days if injections were not repeated at frequent intervals. The sodium and potassium analyses of normal bone marrow cells revealed differences in ionic concentration dissimilar to normal blood cells, the average sodium concentrations being higher and potassium concentrations lower in the former cells. Separation of marrow cells into three groups by prolonged centrifugation demonstrated a progressive increase in sodium and a decrease in potassium concentration from the lower to the upper stratum, possibly indicating a greater degree of ionic pumping in the more dense cells.

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