pH-dependent effects of local anaesthetics in perturbing lipid membranes.
The effects of local anaesthetics lidocaine, benzocaine, carbisocaine and carbisocaine derivatives, KaQ-7 and Ka-O, in perturbing bovine brain lipid membranes or egg lecithin membranes were compared at pH 6.0; 7.0; and 8.0. The electron spin resonance method with stearic acid labeled at carbon position 16 as the spin probe was employed. The perturbation effects of lidocaine and Ka-O were found to increase with increasing pH of the sample, whereas the effect of carbisocaine decreased with increasing pH. The perturbation effects of benzocaine and KaQ-7 were independent of pH. The pH-dependent perturbation effects of the local anaesthetics tested on lipid membrane fairly corresponded with their pH-dependent potency to block nerve action potentials.
D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D001566:Benzocaine / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D002219:Carbamates / Q000494:pharmacology; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology; D008563:Membrane Lipids / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism
D000779:Anesthetics, Local; D002219:Carbamates; D008563:Membrane Lipids; D010713:Phosphatidylcholines; C046030:carbizocaine; D008012:Lidocaine; D001566:Benzocaine