Date of Award
Restricted Access Dissertation
Doctor of Philosophy
Field of Study
Graduate School of Biomedical Sciences
Reeves, Rustin E., Characterization of the Myo-inositol Efflux Pathway in Cultured Bovine Lens Epithelial Cells. Doctor of Philosophy (Biomedical Sciences), December, 1997, 173 pp., 1 table, 28 figures, bibliography, 94 titles. The basic cellular requirement of volume regulation utilizes many different channel and transport pathways working on concord to maintain a constant cell volume. Among these are distinct pathways spontaneously activated by changes in cell volume that modulate the gain or loss of certain organic osmolytes, such as myo-inositol (MI). The major goal of this dissertation is to characterize and identify the mechanism involved in the MI effux pathway and explore its relationship with intracellular polyol accumulation in cultured bovine lens epithelial cells (BLECs). Hypertonic exposure of BLECs causes an increase in MI uptake and aldose reductase enzymatic activity, two events which ultimately influence osmolyte efflux. A biphasic efflux pathway induced by rapid cell swelling (hypotonic-induction) was demonstrated in BLECS switched from hypertonice to physiologic medium. Also, intracellular polyol accumulation from galactose exposure resulted in enhanced activation of the MI efflux pathway (polyol-induction). Chloride channel inhibitors effectively blocked MI efflux suggesting a relationship between anion (chloride) movement and intracellular MI loss from cell to medium. Expression of a chloride channel regulatory protein, pICln, was demonstrated by Northern blot analysis in cultured BLECs. Hypertonic exposure upregulates the expression of pICln mRNA while hypotonicity downregulates expression. The volume-sensitivity for transcription of PICln mRNA in BLECs lends strong support for its role in both anion and osmolyte loss associated with the MI efflux pathway. The MI efflux pathway functions as a “relief value” in cell volume regulation by providing a conduit to alleviate intracellular osmotic stress. The mechanism which evolved to function under normal cellular circumstances in relief of excessive accumulation of intracellular osmolytes (i.e. polyols), may, by design, inadvertently promote the loss of essential intracellular volume and nonvolume regulatory organic solutes. Ironically, under certain pathological conditions, this mechanism, designed to protect the cell from intracellular osmotic stress, may instead be detrimental to the cell by promoting the excessive loss of osmolytes essential for normal cell function.
Reeves, R. E.
"Characterization of the Myo-inositol Efflux Pathway in Cultured Bovine Lens Epithelial Cells" Fort Worth, Tx: University of North Texas Health Science Center;