Na(+)-Ca2+ exchange influences halothane and caffeine contractures of malignant hyperthermic skeletal muscle.
These experiments sought to determine the influence of sarcolemmal Na(+)-Ca2+ exchange on halothane and on caffeine contractures of malignant hyperthermic (MH) skeletal muscle. Fiber bundles excised from MH susceptible pigs (Pietrain) were exposed to halothane (3%) and caffeine (0.5-8.0mM) while Na(+)-Ca2+ exchange was inhibited by reducing extracellular Na+ from 100% to 50, 25 and 0% of control. Halothane contracture magnitude was not altered by 50 or 25% Na+ whereas 0% Na+ increased the contractures by 51%. 0 and 25% Na+ increased the magnitude of caffeine contractures (2-8mM) by 53-176%. These results suggest that external Na+ and the Na(+)-Ca2+ exchange mechanism influences contractures of MH skeletal muscle.
Williams
J H
JH
Department of Biomedical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg 24061.
Lee
J C
JC
Holland
M
M
D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003470:Culture Media; D006221:Halothane / Q000494:pharmacology*; D007700:Kinetics; D008305:Malignant Hyperthermia / Q000378:metabolism / Q000503:physiopathology*; D008565:Membrane Proteins / Q000378:metabolism*; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D019831:Sodium-Calcium Exchanger; D013552:Swine
D002352:Carrier Proteins; D003470:Culture Media; D008565:Membrane Proteins; D019831:Sodium-Calcium Exchanger; D002110:Caffeine; D012964:Sodium; D002118:Calcium; D006221:Halothane