Anesthetics alter the physical and functional properties of the Ca-ATPase in cardiac sarcoplasmic reticulum.
We have studied the effects of the local anesthetic lidocaine, and the general anesthetic halothane, on the function and oligomeric state of the CA-ATPase in cardiac sarcoplasmic reticulum (SR). Oligomeric changes were detected by time-resolved phosphorescence anisotropy (TPA). Lidocaine inhibited and aggregated the Ca-ATPase in cardiac SR. Micromolar calcium or 0.5 M lithium chloride protected against lidocaine-induced inhibition, indicating that electrostatic interactions are essential to lidocaine inhibition of the Ca-ATPase. The phospholamban (PLB) antibody 2D12, which mimics PLB phosphorylation, had no effect on lidocaine inhibition of the Ca-ATPase in cardiac SR. Inhibition and aggregation of the Ca-ATPase in cardiac SR occurred at lower concentrations of lidocaine than necessary to inhibit and aggregate the Ca-ATPase in skeletal SR, suggesting that the cardiac isoform of the enzyme has a higher affinity for lidocaine. Halothane inhibited and aggregated the Ca-ATPase in cardiac SR. Both inhibition and aggregation of the Ca-ATPase by halothane were much greater in the presence of PLB antibody or when PLB was phosphorylated, indicating a protective effect of PLB on halothane-induced inhibition and aggregation. The effects of halothane on cardiac SR are opposite from the effects of halothane observed in skeletal SR, where halothane activates and dissociates the Ca-ATPase. These results underscore the crucial role of protein-protein interactions on Ca-ATPase regulation and anesthetic perturbation of cardiac SR.
Karon
B S
BS
Department of Biochemistry, University of Minnesota Medical School, Minneapolis 55455, USA.
Geddis
L M
LM
Kutchai
H
H
Thomas
D D
DD
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D016880:Anisotropy; D055592:Biophysical Phenomena; D001703:Biophysics; D002135:Calcium-Binding Proteins / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D004285:Dogs; D004789:Enzyme Activation / Q000187:drug effects; D006221:Halothane / Q000494:pharmacology; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D011487:Protein Conformation / Q000187:drug effects; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology; D013816:Thermodynamics; D000099211:Phospholamban
D000777:Anesthetics; D002135:Calcium-Binding Proteins; D000252:Calcium-Transporting ATPases; D006221:Halothane; D008012:Lidocaine; D000099211:Phospholamban