Expression of Two Different Cholecystokinin Receptors in Xenopus Oocytes Injected with mRNA from Rabbit Pancreas ana Rat Hippocampus
| Autor: | Kazuo Kawasaki, Shunji Murata, Masafumi Fujimoto, Yasushi Shigeri, Shunji Shinohara |
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| Rok vydání: | 1996 |
| Předmět: |
Male
medicine.medical_specialty Xenopus Gene Expression Biology Hippocampal formation Cholecystokinin receptor Sincalide Membrane Potentials Rats Sprague-Dawley chemistry.chemical_compound Hormone Antagonists Internal medicine Extracellular medicine Animals RNA Messenger Reversal potential Receptor Egtazic Acid Chelating Agents Cholecystokinin Pharmacology Dose-Response Relationship Drug biology.organism_classification Receptor Cholecystokinin B Rats Receptor Cholecystokinin A Cell biology EGTA Endocrinology chemistry Oocytes Quinolines Calcium Receptors Cholecystokinin Rabbits hormones hormone substitutes and hormone antagonists |
| Zdroj: | Japanese Journal of Pharmacology. 72:9-15 |
| ISSN: | 0021-5198 |
| DOI: | 10.1254/jjp.72.9 |
| Popis: | Electrophysiological responses to cholecystokinin (CCK) were studied in Xenopus oocytes injected with mRNA from rabbit pancreas or rat hippocampus. CCK-octapeptide(26–33) (sulfated form) (CCK-8) elicited inward currents in both groups. In oocytes injected with pancreatic mRNA, CCK-8-induced currents were composed of two components, fast and slow. However, in oocytes injected with hippocampal mRNA, fast currents disappeared. The potency ranking of the agonists and the antagonist indicated that the receptors expressed by pancreatic and hippocampal mRNA were CCKA- and CCKB-subtypes, respectively. Extracellular application of EGTA had little effect on the CCKB-mediated response, but attenuated the CCKA-mediated one. Intracellular injection of EGTA aboUshed the CCKB-mediated response, whereas small smooth currents remained in oocytes expressing the CCKA-receptor. The reversal potentials of the CCKA- and CCKB-receptor-mediated responses were consistent with that for Cl− currents. However, the reversal potential of the small smooth currents in EGTA-loaded oocytes expressing the CCKA-receptors was close to that for a non-selective cation channel. These results suggest that CCK-8 activates at least two different channels, a Ca2+-dependent Cl− channel and a non-selective cation channel in oocytes expressing the CCKA-receptor, while the CCKB-receptor elicits only a Ca2+-dependent Cl− channel. |
| Databáze: | OpenAIRE |
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