The electrical activity pattern of endocrine pituitary cells regulates their basal secretion level. Rat somatotrophs and lactotrophs exhibit spontaneous bursting and have high basal levels of hormone secretion, while gonadotrophs exhibit spontaneous spiking and have low basal hormone secretion. It has been proposed that the difference in electrical activity between bursting somatotrophs and spiking gonadotrophs is due to the presence of large conductance potassium (BK) channels on somatotrophs but not on gonadotrophs. This is one example where the role of an ion channel type may be clearly established. We demonstrate here that BK channels indeed promote bursting activity in pituitary cells. Blocking BK channels in bursting lacto-somatotroph GH4C1 cells changes their firing activity to spiking, while further adding an artificialBKconductance via dynamic clamp restores bursting. Importantly, this burst-promoting effect requires a relatively fastBKactivation/deactivation, as predicted by computational models.Wealso show that adding a fast-activatingBK conductance to spiking gonadotrophs converts the activity of these cells to bursting. Together, our results suggest that differences in BK channel expression may underlie the differences in electrical activity and basal hormone secretion levels among pituitary cell types and that the rapid rate of BK channel activation is key to its role in burst promotion. © 2011 the authors.
CITATION STYLE
Tabak, J., Tomaiuolo, M., Gonzalez-Iglesias, A. E., Milescu, L. S., & Bertram, R. (2011). Fast-activating voltage-and calcium-dependent potassium (BK) conductance promotes bursting in pituitary cells: A dynamic clamp study. Journal of Neuroscience, 31(46), 16855–16863. https://doi.org/10.1523/JNEUROSCI.3235-11.2011
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