title: Local anesthetics inhibit Ca-ATPase in masticatory muscles.
abstract: Local anesthetics have myotoxic effects and inhibit Ca-ATPase activity and Ca transport in skeletal muscles. Such effects have not been fully elucidated in masticatory muscles. We tested the hypothesis that local anesthetics increase myoplasmic calcium in masticatory muscles by inhibiting Ca-ATPase at a concentration similar to that of dental cartridges. The effects of lidocaine and bupivacaine on Ca-ATPase from rabbit masseter and medial pterygoid muscles were tested with radioisotopic and colorimetric methods. Bupivacaine had an action similar to that of lidocaine on Ca-ATPase activity, but less effect on calcium transport. The pre-exposure of the membranes to the anesthetics enhanced the Ca-ATPase activity in the absence of calcium ionophore, supporting their permeabilizing effect. The results demonstrate that amide-type anesthetics do not inhibit calcium binding, but do reduce calcium transport and enzyme phosphorylation by ATP, and suggest that the myoplasmic calcium increase induced by lidocaine and bupivacaine might promote masticatory muscle contraction and eventual rigidity.
authors.affiliation: Biophysics Department, Faculty of Dentistry, University of Buenos Aires, MT de Alvear 2142, C1122AAH, Buenos Aires, Argentina. gabriel@odon.uba.ar
authors.forename: G A
authors.initials: GA
authors.lastname: Sánchez
authors.forename: D
authors.initials: D
authors.lastname: Takara
authors.forename: G L
authors.initials: GL
authors.lastname: Alonso
mesh_terms: D000779:Anesthetics, Local / Q000633:toxicity*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002045:Bupivacaine / Q000633:toxicity; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000633:toxicity; D007425:Intracellular Membranes / Q000187:drug effects; D008012:Lidocaine / Q000633:toxicity; D008410:Masticatory Muscles / Q000187:drug effects* / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*
chemical_list: D000779:Anesthetics, Local; D004791:Enzyme Inhibitors; D008012:Lidocaine; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium; D002045:Bupivacaine