Carboxyl groups at the membrane interface as molecular targets for local anesthetics.
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Louro SR, Anteneodo C, Wajnberg E
Carboxyl groups at the membrane interface as molecular targets for local anesthetics.
Biophys Chem. 1998 Aug 4;74(1):35-43.
- PubMed ID
- 9742684 [ View in PubMed]
- Abstract
The interaction of the tertiary amine drugs chlorpromazine and dibucaine in their cationic form with carboxyl groups at the membrane surface is studied at concentrations relevant to anesthesia. Spin-labeled stearic acid is used both to provide the carboxyl groups and to monitor binding and ionization behavior in egg lecithin liposomes. Membrane anesthetic concentrations are spectrophotometrically obtained. They are shown to determine the drug influence on carboxyl groups at the membrane surface, independently of aqueous concentrations. The intramembrane association constants (related to the usual aqueous phase ones through the partition coefficient) of the drugs with fatty acids are determined. The same value (10(2) M-1) is obtained for both drugs, suggesting that it is approximately the same for all tertiary amine local anesthetics. pH titrations of anesthetic-treated spin-labeled membranes are performed. The observed shifts in the fatty acid pK are higher than can be produced assuming uniform distribution of the drug in the membrane surface, implying that there is an increased affinity of local anesthetics for superficial carboxyl. This affinity could account for the resting block of voltage-gated Na+ channels. Under these considerations, local anesthetic binding sites at voltage-gated Na+ channels and at sarcoplasmic reticulum Ca(2+)-ATPase are proposed.
DrugBank Data that Cites this Article
- Drug Targets
Drug Target Kind Organism Pharmacological Action Actions Cinchocaine Sodium channel protein type 10 subunit alpha Protein Humans YesInhibitorDetails Cinchocaine Sodium channel protein type 5 subunit alpha Protein Humans YesInhibitorDetails