Effects of tyrosine phosphatase inhibitor phenylarsine oxide on excision-activated calcium channels and neurite outgrowth in Lymnaea neurons
Abstract
The primary purpose of the present study was to investigate the regulation of excision-activated calcium channels (HP channels) in cultured Lymnaea neurons. HP channels, which are divalent-selective and voltage-independent, can be activated experimentally by excising a small patch of plasma membrane from the cell. Little is know about the possible physiological regulators of these channels. In this study, the patch-clamp technique was used to demonstrate that pretreatment with a protein tyrosine phosphatase inhibitor, either pervanadate (0.5 mM) or phenylarsine oxide (1 to 7 $\mu M$), inhibited the activation of HP channels by excision, while serine/threonine phosphatase inhibitor, okadaic acid (1 $\mu M$), had no effect. The inhibitory effect of phenylarsine oxide on-the activation of HP channels was blocked by simultaneous addition of dimercaptopropanol but not beta-mercaptoethanol. In addition, HP channels were also found in both the soma and the neurite. Unlike intact soma patches, intact neurite patches had active HP channels. However, the HP channels in both the soma and neurite were inhibited by phenylarsine oxide. Another phase of this study involved the determination of the physiological role of HP channels in Lymnaea neurons. Phenylarsine oxide but not okadaic acid inhibited neurite outgrowth in neurons cultured up to 48 hours. Acute application of phenylarsine oxide to neurons resulted in suppression of neurite outgrowth and retraction of pre-formed neurites. These results suggest that HP channels may be regulated by the tyrosine phosphorylation signaling pathway and may play a physiological role in neurite outgrowth.
Degree
Ph.D.
Advisors
Vanable, Purdue University.
Subject Area
Neurology|Anatomy & physiology|Animals
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