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Solubilization and Characterization of the Nitrendipine Receptor in Rat Brain

Authors


  • Parts of this study were presented at the 66th and 67th Regional Meetings (Kinki Area) of the Japanese Pharmacological Society (Fukui et al., 1985; Takemura et al., 1985).

Address correspondence and reprint requests to Dr. M. Takemura at Department of Pharmacology II, Osaka University School of Medicine, 4–3–57 Nakanoshima, Kita-ku, Osaka 530, Japan.

Abstract

Abstract: The nitrendipine receptor associated with the voltage-dependent calcium channel in rat brain was solubilized by detergent extraction and sonication. The detergent solution used for extraction consisted of 10 mM 3-[(3-cholamidopropyl)dimethylammonio] - 1 - propanesulfonate (CHAPS), 0.25% (wt/vol) polyoxyethylene 20 cetyl ether (Brij 58), and 0.025% (wt/vol) polyoxyethylene 17 cetyl stearyl ether (Lubrol WX) in the presence of 30% (wt/vol) glycerol as a stabilizer. The molecular weight of the receptor was estimated to be 1,800K by Sephacryl S-500 gel filtration and 800K by sucrose density gradient sedimentation. The equilibrium dissociation constant of [3H]nitrendipine to the solubilized receptors was 5.6 nM, which is ∼10 times that of the membrane-bound receptor. The binding of nitrendipine to the receptor was inhibited noncompetitively by the structurally unrelated calcium channel inhibitors verapamil and prenylamine; their concentrations for 50% inhibition were both 1.0 ∼ 10−7M, and they caused maximal inhibitions of 70 and 100%, respectively.

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