Effect of prolonged in vitro lithium treatment on calcium transients in frog twitch muscle fibres and its reversal by exogenous myo-inositol.
Using arsenazo III as an intracellular indicator to monitor the calcium transients elicited by voltage-clamp depolarizing pulse, the effect of prolonged in vitro lithium treatment on excitation--contraction coupling in frog twitch muscle fibres was investigated. Incubation in 10 mM Li+ Ringer's solution for 2 days caused a 46% increase in the amplitude of the calcium transients, while treatment with 30 mM Li+ for 2 days produced a depression of 44%. Shortening the bathing time to 1 day, the decrease of calcium transients caused by 30 mM Li+ was reversed to a small increase. For the 2-day incubation, both the increase in the amplitude with 10 mM and the decrease with 30 mM Li+ were abolished by the presence of 1 mM myo-inositol in the bathing medium. These results imply that the turnover of inositol phospholipids is involved in regulating excitation-contraction coupling in skeletal muscle fibres.
Zhu
P H
PH
Department of Cellular and Molecular Neurobiology, Shanghai Institute of Physiology, Chinese Academy of Sciences.
Fu
D X
DX
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D007294:Inositol / Q000494:pharmacology*; D007700:Kinetics; D008094:Lithium / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D011898:Ranidae
D007294:Inositol; D008094:Lithium; D002118:Calcium