Abstract
Wild-type or mutant H297N or H297Q of the mu-opioid receptor were co-expressed with the inwardly rectifying potassium channel GIRK1 in oocytes from Xenopus laevis. Under voltage clamp, pairs of concentration response curves were generated using the agonist normorphine in a bathing medium containing 38.5 mM sodium or an identical medium in which the sodium was replaced by an equimolar concentration of choline. The maximum currents were greater in the presence of sodium by about 30% at wild-type receptors and by about 100% at the mutant receptors. The EC(50) values tended to increase somewhat as well, though these differences reached statistical significance only for the mutant H297Q. Flame photometry detected no change in the intracellular sodium or potassium concentrations of oocytes, suggesting that the effect of sodium was solely extracellular. Thus sodium, long known for its effects on in vitro ligand binding at mu-opioid receptors, also affects overall transduction as revealed in the Xenopus oocyte model of a complete, living cell system.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.