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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Changes in Intracellular Chloride During Osmotic Stress and L-alanine Uptake in Mouse Hepatocytes

Wang, Kening 01 October 1992 (has links)
A stable intracellular ionic environment is necessary for hepatocytes to function normally. Thus, during hypotonic shock or L-alanine uptake, hepatocytes swell and then exhibit a regulatory volume decrease (RVD), which comprises an increase in K$\sp+$ conductance (G$\sb{\rm K}$), an increased K$\sp+$ efflux, and a hyperpolarization of transmembrane potential (V$\sb{\rm m}$). Since hepatocyte intracellular Cl$\sp-$ has been demonstrated to distribute passively with V$\sb{\rm m}$, this study is designed to test the hypothesis that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V$\sb{\rm m}$ might provide an electromotive force for the efflux of hepatocyte intracellular Cl$\sp-$, which in turn would contribute osmotically to the RVD in hepatocytes. Double-barreled ion-selective microelectrodes were used to measure the changes of hepatocyte transmembrane potential, intracellular ionic activities (especially intracellular Cl$\sp-$ activity, (a$\sp{\rm i}\sb{\rm Cl}$)), and intracellular water volume during either anisotonic stress or L-alanine uptake. Hepatocyte V$\sb{\rm m}$ hyperpolarized, (a$\sp{\rm i}\sb{\rm Cl}$) decreased, intracellular K$\sp+$ activity (a$\sp{\rm i}\sb{\rm K}$) decreased, and intracellular water volume increased during hyposmotic stress. When perfused with L-alanine, hepatocyte V$\sb{\rm m}$ exhibited a transient depolarization followed by repolarization and then underwent a constant hyperpolarization. Meanwhile, hepatocyte intracellular Na$\sp+$ activity (a$\sp{\rm i}\sb{\rm Na}$) increased, a$\sp{\rm i}\sb{\rm K}$ & a$\sp{\rm i}\sb{\rm Cl}$ decreased, and intracellular water volume increased. In both hypotonic shock and L-alanine uptake conditions, the decreased a$\sp{\rm i}\sb{\rm K}$ could be attributed to cell swelling. However, the decrease in a$\sp{\rm i}\sb{\rm Cl}$ was greater than could be accounted for by cell swelling. When the change of V$\sb{\rm m}$ was inhibited by K$\sp+$ channel blockers, the change of a$\sp{\rm i}\sb{\rm Cl}$ was also inhibited. Based on the measured a$\sp{\rm i}\sb{\rm Cl}$, Cl$\sp-$ was always at its electrochemical equilibrium in all of the control and experimental conditions. The conclusions of this study emphasize the passive distribution of hepatocyte intracellular Cl$\sp-$ with the changes of V$\sb{\rm m}$ induced by hypotonic stress and L-alanine uptake. Thus, the data strongly support the idea that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V$\sb{\rm m}$ provides electromotive force for the efflux of hepatocyte intracellular Cl$\sp-$. This could contribute to hepatocyte volume regulation during both hypotonic shock and organic solute transport.

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