MON-039 Lactotrope Cells and Chloride Toxicity: What about a Possible More General Mechanism?

Rat lactotrope cells in primary culture exhibit physiological properties closely associated with chloride ions (Cl-) homeostasis. We have studied the regulation of intracellular Cl- concentrations (Cl-)I and its relation to the membrane resting potential using a combination of electrophysiology and spectrofluorimetry Using the same techniques we have realized similar experiments with PC12 cells. We show that: the patch pipette does not always impose its Cl- concentrations. In rat lactotrope cells, membrane resting potential is partially determined by (Cl-). Besides ion channels activity, electroneutral ion transport as K+-Cl- and Na+-K+-2Cl-, participate actively in maintaining a high (Cl-). Finally, Cl- homeostasis is linked to cell energetics since low (Cl-)i decreases cell ATP content, ATP/ADP ratio and modify phosphorilative oxydations. Finally, pHi appears as a determinant in the balance between the aerobic and anaerobic pathway. In addition, we also show that PC12 cells have cellular regulating pHi mechanisms associated with anionic exchanger activation and that cell toxicity is mediated by an acidification of the cytosol, due to the activation of AE3 and AE2, measured on individual cells. Our results add strong evidence for a primordial role of functional alteration of anionic exchanges chloride homeostasis and pHi regulation in dopaminergic cell death. Finally, these aspects of chloride biologic effects may be important in considering the use of this ion in field of agronomy for instance and its consequence on bees populations.