EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Electrophysiology of phagocytic membranes intracellular potassium activity and potassium equilibrium potential in macrophage polykaryons


Biochimica et Biophysica Acta 899(2): 213-221
Electrophysiology of phagocytic membranes intracellular potassium activity and potassium equilibrium potential in macrophage polykaryons
The role of K+ as current carrier during the slow membrane hyperpolarizations (SH) elicited by iontophoretic Ca2+ injections into macrophage polykaryons is studied. The intracellular K+ activity (aK) and the K+ equilibrium potential (EK) are measured using ion-sensitive microelectrodes. The mean value of aK is 84 .+-. 5 mM in a culture medium containing 5.3 mM K+, but increases to 100 .+-. 8 mM when the extracellular K+ concentration is raised to 30.3 mM. Under the same conditions the values of EK obtained from the Nernst equation are -81 .+-. 2 mV and -40 .+-. 2 mV, respectively. The reversal potentials (ER) of the SH are calculated from changes observed in transmembrane potential and input resistance, according to an equivalent model based only on passive ionic fluxes. The mean ER values obtained are -74 .+-. 8 mV in the presence of low K+ concentration and -37 .+-. 3 mV for the high K+ medium. These values are significantly smaller than the estimated EK for the corresponding situations. Evidence for the existence of an electogenic (Na+ + K+)-ATPase activity is also presented. The evidence indicates that an increase in the membrane potassium permeability can account for about 90% of the total permeability change occurring during the SH.


Accession: 005349905



Related references

Electrophysiology of phagocytic membranes: intracellular K+ activity and K+ equilibrium potential in macrophage polykaryons. Biochimica et Biophysica Acta 899(2): 213-221, 1987

Electrophysiology of phagocytic membranes. Role of divalent cations in membrane hyperpolarizations of macrophage polykaryons. Biochimica et Biophysica Acta 856(2): 362-372, 1986

Intracellular potassium activity potassium equilibrium potential and membrane potential of carotid body glomus cells. Brain Research 381(2): 405-408, 1986

Intracellular and extracellular potassium activities and the potassium equilibrium potential in partially depolarized human atrial cells. Journal of Molecular & Cellular Cardiology 19(5): 477-486, 1987

Electrophysiology of phagocytic membranes. I. Potassium-dependent slow membrane hyperpolarizations in mice macrophages. Biochimica et Biophysica Acta 469(3): 257-263, 1977

Electrophysiology of phagocytic membranes. III. Evidence for a calcium-dependent potassium permeability change during slow hyperpolarizations of activated macrophages. Biochimica et Biophysica Acta 640(2): 500-511, 1981

The "anomalous" relationship between the concentration of potassium in the medium and the membrane potential of muscle fibers with a decreased intracellular potassium concentration. II. Rate of forward and reverse K42 transport through muscle fiber membranes in saccharose-sulfate solutions with potassium concentrations of 2.5 and 75 mM. Tsitologiia 18(1): 66-73, 1976

Electro physiology of phagocytic membranes induction of slow membrane hyper polarizations in macrophages and macrophage polykaryons by intra cellular calcium injection. Journal of Membrane Biology 61(2): 81-90, 1981

Influence of changes in external potassium and chloride ions on membrane potential and intracellular potassium ion activity in rabbit ventricular muscle. Journal of Physiology 256(3): 663-689, 1976

Q/I potassium availability parameters in calcareous soils. I. Equilibrium potassium activity ratio and labile pool of potassium. Agrochimica 24(2/3): 245-254, 1980