Effect of halothane on the oligomerization of the sarcoplasmic reticulum Ca(2+)-ATPase.
The exact molecular mechanism of inhalational anesthetics remains obscure. Since the enzyme activity of the sarcoplasmic reticulum Ca(2+)-ATPase from skeletal muscle fibres is modified by halothane and because protein-protein interactions play an important role in the regulation of Ca(2+)-regulatory proteins, we investigated the effect of this volatile drug on the oligomerization of the fast-twitch Ca(2+)-ATPase. Using electrophoretic separation following incubation with halothane, increases in relative molecular mass were determined by immunoblotting with a monoclonal antibody to the SERCA1 isoform of the Ca(2+)-ATPase. Distinct drug-induced decreases in electrophoretic mobility indicated oligomerization of the native Ca(2+)-pump by halothane, comparable to crosslinking-mediated formation of homo-tetramers. Determination of the effect of halothane on enzyme activity suggested that halothane-mediated protein aggregation triggers a partial inhibition of Ca(2+)-pump units. Thus, halothane appears to exert its action via specific peptide binding sites and not indirectly by lipid perturbation. These findings support the protein theory of anesthetic action.
Brennan
L K
LK
Department of Pharmacology, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, 4, Ireland.
Froemming
G R
GR
Ohlendieck
K
K
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001665:Binding Sites; D000252:Calcium-Transporting ATPases / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006221:Halothane / Q000494:pharmacology*; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology*; D011487:Protein Conformation; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*
D000777:Anesthetics; D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D003902:Detergents; D007527:Isoenzymes; D000252:Calcium-Transporting ATPases; D006221:Halothane