Morphine Inhibits Calcium Influx and the Response to Acetylcholine in Xenopus Oocytes |
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Authors: | D. Lipinsky Y. Oron Y. Sarne |
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Affiliation: | Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel |
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Abstract: | Abstract: Incubation of intact Xenopus oocytes with the opioid radioligand [3H]diprenorphine (0.5 n M ) resulted in specific binding of 1.7 ± 0.3 fmol per oocyte. Morphine (10 μ M ) inhibited the uptake of 45Ca2+ into the oocyte by 66 ± 9%. The opioid antagonist naltrexone partially blocked this effect of morphine. Preincubation of oocytes with morphine (10 μ M , 2 min) partially inhibited the fast and slow responses of the oocyte to acetylcholine by 26 and 52%, respectively. We conclude that native Xenopus oocytes possess opioid receptors that may modulate the muscarinic response by limiting calcium influx into the cell. |
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Keywords: | Xenopus oocyte Opioid receptor Morphine Ca2+ fluxes Acetylcholine Muscarinic response |
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