title: Intracellular mechanism of action of isoflurane and halothane on striated muscle of the rabbit.
abstract: Studies were conducted on the effects of isoflurane and halothane on intracellular mechanisms of striated muscle contraction: Ca2+ activation of the contractile proteins and Ca2+ uptake and release from the sarcoplasmic reticulum. Functionally skinned muscle fibers (sarcolemma disrupted by homogenization) from isolated papillary muscle (PM), soleus (SL) (slow-twitch skeletal muscle), and adductor magnus (AM) (fast-twitch skeletal muscle) of rabbits were mounted on a photodiode tension transducer. They were immersed in control solution (saturated with N2), then in test solution (saturated with anesthetic-N2 mixture), and in control solution again. The following two studies were carried out: 1) in the study of Ca2+ -activated tension development of the contractile proteins, free Ca2+ concentration in the bathing solution was controlled by the use of a high EGTA (7 mM), and 2) in the study of Ca2+ uptake and release from the sarcoplasmic reticulum (SR), Ca2+ was loaded into the SR and released with caffeine and the resulting tension transients were measured. Isoflurane (1-4%) decreased (6-9%) the maximal Ca2+ -activated tension development in PM and SL but more in PM than in SL. In AM, however, isoflurane and halothane (1-3%) produced no change. Isoflurane decreased submaximal Ca2+ -activated tension development in PM, but effected no change in it in SL. Isoflurane and halothane increased the tension development in AM to the extent of producing a shift to the left in the pCa-tension curves of less than or equal to 0.1 pCa unit.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D004347:Drug Interactions; D006221:Halothane / Q000494:pharmacology*; D066298:In Vitro Techniques; D007530:Isoflurane / Q000494:pharmacology*; D008738:Methyl Ethers / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism
chemical_list: D008738:Methyl Ethers; D002110:Caffeine; D007530:Isoflurane; D002118:Calcium; D006221:Halothane