Voltage-gated potassium (K) channels are important in controlling a neuron's excitability. In this thesis I show that neonatal rat nodose and superior cervical ganglion (SCG) neurons express three voltage-gated K currents: a non-inactivating delayed rectifier type current (IK); a rapidly inactivating A-current (IAf), and; a slowly inactivating A-current (IAs). The channels that underlie IAf and IAs differ in their voltage-dependent, kinetic and pharmacological properties, but share the same single channel conductance, suggesting that rapidly and slowly inactivating A-channels are distinct subtypes of the same basic channel. My preliminary molecular biology experiments establish an approach for identifying the genes that encode for IAf, IAs and IK channels on SCG neurons. By studying the expression of IAf, IAs and IK on peripheral neurons during the first 2 postnatal weeks, I showed that there is no change in the expression of the 3 currents on nodose neurons, whereas the outward current on SCG neurons changes significantly from one dominated by IAs to one dominated by IAf. These results indicate that the pattern of developmental expression of similar types of K channels can differ for each neuron type. Next, I investigated various factors involved in the postnatal control of expression of K channels on SCG neurons. I demonstrated that neither preganglionic nor target factors influence postnatal changes in K currents. However, I observed that neonatal SCG neurons that develop in culture without other cell types lose their expression of IAf and IAs, suggesting that extrinsic factor(s) are involved in the regulation of the expression of these currents. I showed that this loss of A-currents is due, in part, to the absence of a soluble factor provided by nonneuronal cells. In addition, my analysis of the different patterns of expression of voltage-gated K currents suggests that peripheral neurons use intrinsic mechanisms to coordinate their expression of IAf, IAs and
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.39454 |
| Date | January 1992 |
| Creators | McFarlane, Sarah |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001305394, proquestno: NN80462, Theses scanned by UMI/ProQuest. |
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