{"doi":"10.17615/k6x6-7b90","title":"D2 dopamine receptor activation of potassium channels in identified rat lactotrophs: whole-cell and single-channel recording","abstract":"Dopamine (DA) is the major physiological regulator of prolactin secretion from the anterior pituitary, exerting a tonic inhibitory control that is mediated by D2 DA receptors. D2 receptors in both the anterior pituitary and CNS are thought to produce some of their inhibitory effects via a coupling to potassium (K+) channels to increase K+ conductance. 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+ channels that underlie the response in primary rat lactotrophs. We demonstrate that DA (5 nM to 1 microM) or D2- selective agonists (RU24213 and quinpirole) evoke a hyperpolarization of membrane potential that was blocked by D2 antagonists and associated with an increased K+ 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+, varied as a function of K+ concentration, exhibited some inward rectification, and was Ca2+ independent. The current was insensitive to tetraethylammonium (TEA; 10 mM), partially blocked by 4-aminopyridine (4-AP; 5 mM), and almost completely inhibited by quinine (100 microM). Cell-attached recordings in the presence of DA or a D2 agonist revealed the opening of a K+ channel that was not present in the absence of DA or when a D2 receptor antagonist was included with DA. Analysis of the single- channel current showed the current-voltage relationship to be linear at negative patch potentials and yielded a unitary conductance of 40.2 pS in the presence of 150 mM KCl. The channels were not blocked by TEA (10 mM), were slightly suppressed by 4-AP (5 mM), and were almost completely inhibited by quinine (100 microM). These experiments establish that in primary rat lactotrophs, DA acts at D2 receptors to activate the opening of single K+ channels, which results in an increase in K+ conductance and associated membrane hyperpolarization. This is the first characterization of single DA-activated K+ channels in an endocrine cell.","journal":"UNC Libraries","year":2021,"id":210572,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9564,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":799560,"name":"Gerry S. Oxford","orcid":null,"position":1,"is_corresponding":false},{"id":799561,"name":"LC Einhorn","orcid":null,"position":2,"is_corresponding":false},{"id":799559,"name":"K. A. Gregerson","orcid":null,"position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:52:12.491146Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}