Journal
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS
Volume 329, Issue 3, Pages 978-986Publisher
AMER SOC PHARMACOLOGY EXPERIMENTAL THERAPEUTICS
DOI: 10.1124/jpet.108.146175
Keywords
-
Categories
Funding
- National Institutes of Health National Institute on Alcohol Abuse and Alcoholism [1F31-AA01547401A1, 5RO1-AA0800318, R37-AA1205403]
- NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM [R37AA012054] Funding Source: NIH RePORTER
Ask authors/readers for more resources
Neurons are highly differentiated and polarized cells, whose various functions depend upon the compartmentalization of ion channels. The rat hypothalamic-neurohypophysial system (HNS), in which cell bodies and dendrites reside in the hypothalamus, physically separated from their nerve terminals in the neurohypophysis, provides a particularly powerful preparation in which to study the distribution and regional properties of ion channel proteins. Using electrophysiological and immunohistochemical techniques, we characterized the large-conductance calcium-activated potassium (BK) channel in each of the three primary compartments (soma, dendrite, and terminal) of HNS neurons. We found that dendritic BK channels, in common with somatic channels but in contrast to nerve terminal channels, are insensitive to iberiotoxin. Furthermore, analysis of dendritic BK channel gating kinetics indicates that they, like somatic channels, have fast activation kinetics, in contrast to the slow gating of terminal channels. Dendritic and somatic channels are also more sensitive to calcium and have a greater conductance than terminal channels. Finally, although terminal BK channels are highly potentiated by ethanol, somatic and dendritic channels are insensitive to the drug. The biophysical and pharmacological properties of somatic and dendritic versus nerve terminal channels are consistent with the characteristics of exogenously expressed alpha beta 1 versus alpha beta 4 channels, respectively. Therefore, one possible explanation for our findings is a selective distribution of auxiliary beta 1 subunits to the somatic and dendritic compartments and beta 4 to the terminal compartment. This hypothesis is supported immunohistochemically by the appearance of distinct punctate beta 1 or beta 4 channel clusters in the membrane of somatic and dendritic or nerve terminal compartments, respectively.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available