Francisco Alvarez (Committee Member), James Olson (Advisor), Christopher Wyatt (Committee Member)
Master of Science (MS)
Swollen cells expel osmolytes to decrease volume in a process referred to as Regulatory Volume Decrease, or RVD. The plasma membrane current ICl,swell is ubiquitously expressed in mammalian cells and contributes significantly to RVD. In a variety of cell types, activation of ICl,swell is enhanced by nucleotide signaling. In this study, we used human astrocytoma cells to examine whether nucleotide signaling is necessary or sufficient for ICl,swell activation. Three clones of the 1321N1 human astrocytoma cell line were used for voltage clamp recordings. One clone was transfected with P2Y1 receptors, another with P2Y2 receptors and a third was devoid of any P2Y receptors (Parental). In physiological solutions, hyposmotic exposure (HOE) caused increased membrane conductance in each cell line. HOE also depolarized the reversal potential in P2Y1 and P2Y2, but not in Parental, cell lines. In solutions containing no permeable cations, HOE activated ICl,swell in morphologically round cells of each cell line and in morphologically flat P2Y1 and P2Y2 cells. However, morphologically flat Parental cells did not demonstrate HOE-induced ICl,swell activity. Exogenous ATP activated a chloride current with an electrophysiological profile different from ICl,swell. I conclude that P2Y nucleotide signaling may play a role in gating ICl,swell, but is not necessary for its activation. P2Y receptor stimulation is sufficient to activate a chloride current, but whether the response is mediated by P2Y1 or P2Y2 receptors requires further investigation.
Department or Program
Department of Neuroscience, Cell Biology & Physiology
Year Degree Awarded
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