Abstract

SANCHEZ, Gabriel A; CASADOUMECQ, Ana C; ALONSO, Guillermo L  and  TAKARA, Delia. Inhibitory effect of lidocaine on the sarcoplasmic reticulum Ca²⁺- dependent ATPase from temporalis muscle. Acta odontol. latinoam. [online]. 2010, vol.23, n.2, pp.92-98. ISSN 1852-4834.

Myotoxic effects of local anesthetics on skeletal muscle fibers involve the inhibition of sarcoplasmic reticulum Ca2+-dependent ATPase activity and Ca2+ transport. Lidocaine is a local anesthetic frequently used to relieve the symptoms of trigeminal neuralgia. The aim of this work was to test the inhibitory and/or stimulatory effect of lidocaine on sarcoplasmic reticulum Ca2+-dependent ATPase isolated from rabbit temporalis muscle. Ca2+-dependent ATPase activity was determined by a colorimetric method. Calcium-binding to the Ca2+- dependent ATPase, Ca2+ transport, and phosphorylation of the enzyme by ATP were determined with radioisotopic techniques. Lidocaine inhibited the Ca2+-dependent ATPase activity in a concentration- dependent manner. The preincubation of the sarcoplasmic reticulum membranes with lidocaine enhanced the Ca2+- dependent ATPase activity in the absence of calcium ionophore. Lidocaine also inhibited both Ca2+ uptake and enzyme phosphorylation by ATP but had no effect on Ca2+-binding to the enzyme. We conclude that the effect of lidocaine on the sarcoplasmic reticulum Ca2+-dependent ATPase from temporalis muscle is due to the drug’s direct interaction with the enzyme and the increased permeability of the sarcoplasmic reticulum membrane to Ca.

Keywords : Sarcoplasmic reticulum; Ca²⁺-dependent ATPase; Temporal muscle; Local anesthetics; Lidocaine; Calcium transport.

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