Spelling suggestions: "subject:"electrochemical equilibrium"" "subject:"lectrochemical equilibrium""
1 |
Mouse Hepatocyte Membrane Potential and Chloride Activity During Osmotic StressWang, K., Wondergem, R. 01 January 1992 (has links)
Hepatocyte transmembrane potential (V(m)) during osmotic stress responds as an osmometer, in part because of changes in membrane K+ conductance. This may contribute to the electromotive force that drives transmembrane Cl- fluxes. To test this, double-barreled ion-sensitive microelectrodes were used to measure changes in steady-state intracellular Cl- activity (a(Cl)/(i)) during osmotic stress applied to mouse liver slices. Hyperosmotic and hyposmotic conditions were created by rapidly switching to a solution in which sucrose concentrations were increased or reduced, respectively. Hyperosmotic stress [1.4 x control osmolality (280 mosmol/kgH2O)] decreased hepatocyte V(m) 46% from -39 ± 1 to -21 ± 1 mV (SE; n = 16 animals). Corresponding a(Cl)/(i) increased twofold from 19 ± 2 to 38 ± 3 mM. This shifted the Cl- equilibrium potential (E(Cl)) 19 mV, from -38 ± 0.3 to -19 ± 2 mV. Hyposmotic stress [0.71 x control osmolality (290 mosmol/kgH2O)] increased hepatocyte V(m) 64% from -28 ± 1 to -46 ± 1 mV (SE; n = 13 animals). Corresponding a(Cl)/(i) decreased 0.53-fold from 17 ± 1 to 8 ± 1 mM. This shifted the E(Cl) 20 mV from -26 ± 2 to -46 ± 3 mV. Thus hepatocyte a(Cl)/(i) is in electrochemical equilibrium with V(m). The paired measurements above were repeated after addition of K+-channel blockers quinine or Ba2+. Ba2+ (2 mM) had no effect on either V(m) or a(Cl)/(i) during hyperosmotic stress; however, Ba2+ significantly inhibited changes in V(m) and a(Cl)/(i) during hyposmotic stress. Effects of quinine (0.5 mM) on V(m) and a(Cl)/(i) during both hyperosmotic stress and hyposmotic stress were similar to those of Ba2+. A previous report shows that inhibition of hyposmotic stress-induced V(m) changes results in loss of hepatocyte volume regulation and greater swelling. Thus osmotic stress-induced changes in a(Cl)/(i) are nowhere near those predicted by cell water volume changes based on transmembrane osmotic pressure differences. We conclude that these larger changes in a(Cl)/(i) resulted from voltage-driven transmembrane Cl- fluxes.
|
2 |
Electrokinetic flow in micro- and nano-fluidic componentsZheng, Zhi 19 November 2003 (has links)
No description available.
|
Page generated in 0.086 seconds