Kir3.1/3.2 encodes an I KACh-like current in gastrointestinal myocytes
| Autor: | Burton Horowitz, Elaine R. M. Flynn, Rebecca L. Walker, Karri K. Bradley, James L. Kenyon, William J. Hatton, Helen S. Mason |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
medicine.medical_specialty
Potassium Channels Physiology Xenopus Gene Expression Transfection Xenopus laevis Dogs Digestive System Physiological Phenomena GTP-Binding Proteins Physiology (medical) Internal medicine Gene expression Muscarinic acetylcholine receptor medicine Animals Humans Myocyte RNA Messenger Potassium Channels Inwardly Rectifying Receptor Ion channel Hepatology biology Reverse Transcriptase Polymerase Chain Reaction Electric Conductivity Gastroenterology Muscle Smooth biology.organism_classification Immunohistochemistry Receptors Muscarinic Molecular biology Acetylcholine Potassium channel Intestines Endocrinology G Protein-Coupled Inwardly-Rectifying Potassium Channels Barium Digestive System Ion Channel Gating medicine.drug |
| Zdroj: | American Journal of Physiology-Gastrointestinal and Liver Physiology. 278:G289-G296 |
| ISSN: | 1522-1547 0193-1857 |
| Popis: | Expression of the Kir3 channel subfamily in gastrointestinal (GI) myocytes was investigated. Members of this K+ channel subfamily encode G protein-gated inwardly rectifying K+ channels ( I KACh) in other tissues, including the heart and brain. In the GI tract, I KACh could act as a negative feedback mechanism to temper the muscarinic response mediated primarily through activation of nonselective cation currents and inhibition of delayed-rectifier conductance. Kir3 channel subfamily isoforms expressed in GI myocytes were determined by performing RT-PCR on RNA isolated from canine colon, ileum, duodenum, and jejunum circular myocytes. Qualitative PCR demonstrated the presence of Kir3.1 and Kir3.2 transcripts in all smooth muscle cell preparations examined. Transcripts for Kir3.3 and Kir3.4 were not detected in the same preparations. Semiquantitative PCR showed similar transcriptional levels of Kir3.1 and Kir3.2 relative to β-actin expression in the various GI preparations. Full-length cDNAs for Kir3.1 and Kir3.2 were cloned from murine colonic smooth muscle RNA and coexpressed in Xenopus oocytes with human muscarinic type 2 receptor. Superfusion of oocytes with ACh (10 μM) reversibly activated a Ba2+-sensitive and inwardly rectifying K+current. Immunohistochemistry using Kir3.1- and Kir3.2-specific antibodies demonstrated channel expression in circular and longitudinal smooth muscle cells. We conclude that an I KAChcurrent is expressed in GI myocytes encoded by Kir3.1/3.2 heterotetramers. |
| Databáze: | OpenAIRE |
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