D sub(2) dopamine receptor activation of potassium channels in identified rat lactotrophs: Whole-cell and single-channel recording

Utilizing the reverse hemolytic plaque assay and patch-clamp techniques, we characterize the actions of DA on membrane potential and associated DA-activated whole-cell current, as well as the single K super(+) channels that underlie the response in primary rat lactotrophs. We demonstrate that DA or...

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Bibliographic Details
Published in:The Journal of neuroscience 1991-01, Vol.11 (12), p.3727-3737
Main Authors: Einhorn, L C, Gregerson, KA, Oxford, G S
Format: Article
Language:English
Subjects:
electrophysiological recording
pituitary (anterior)
potassium
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Summary:Utilizing the reverse hemolytic plaque assay and patch-clamp techniques, we characterize the actions of DA on membrane potential and associated DA-activated whole-cell current, as well as the single K super(+) channels that underlie the response in primary rat lactotrophs. We demonstrate that DA or D sub(2)-selective agonists evoke a hyperpolarization of membrane potential that was blocked by D sub(2) antagonists and associated with an increased K super(+) conductance. Whole-cell current responses to ramp voltage commands revealed a DA-activated current whose reversal potential was near the calculated Nernst potential for K super(+), varied as a function of K super(+) concentration, exhibited some inward rectification, and was Ca super(2+) independent. The current was insensitive to tetraethylammonium (TEA), partially blocked by 4-aminopyridine (4-AP), and almost completely inhibited by quinine. Cell-attached recordings in the presence of DA or a D sub(2) agonist revealed the opening of a K super(+) channel that was not present in the absence of DA or when a D sub(2) receptor antagonist was induced with DA.
ISSN:0270-6474