AHP's, HAP's and DAP's: how potassium currents regulate the excitability of rat supraoptic neurones.
We have constructed mathematical models of the electrical activity of two hypothalamic supraoptic neuro-secretory cell-types, and we support our models with new calcium imaging and in vitro electrophysiological data. These cells are neurones that project to the pituitary gland and secrete either of two hormones, oxytocin or vasopressin, into the blood from their axonal terminals. Oxytocin-secreting and vasopressin-secreting cells are closely related and physically they differ only subtly, however when physiologically stressed their discharge patterns are dramatically distinct. We first show how each potassium current contributes to the action-potentials and after-potentials observed in these cells, and we show how these after-potentials are correlated to intra-cellular calcium elevations. We then show how these currents regulate the excitability of these cells and consequently shape their discharge pattern.
Roper
Peter
P
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. pete.roper@nih.gov
Callaway
Joseph
J
Shevchenko
Talent
T
Teruyama
Ryoichi
R
Armstrong
William
W
D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005260:Female; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D008954:Models, Biological; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin; D010455:Peptides / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D051381:Rats; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014667:Vasopressins
D010455:Peptides; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D014667:Vasopressins; D010121:Oxytocin; C064719:iberiotoxin; D002118:Calcium