Ryanodine and theophylline-induced depletion of energy stores in amphibian muscle.
The effects of high and low levels of ryanodine on theophylline-induced energy depletion were studied in isolated frog sartorius muscle. Whereas low concentrations of ryanodine (1-10 microM) did not change high energy phosphate contents (PE) after 60 min, high levels (100 microM) reduced resting energy contents by 60% after 60 min. Subcontracture levels of theophylline (2 mM), in the presence of high ryanodine, produced an 80% PE depletion, suggesting possible additive or synergistic effects of these two agents. In contrast to theophylline-induced depletion, neither the ryanodine-induced depletion nor the theophylline-plus-ryanodine-induced depletion of PE seemed sensitive to inhibition by 1 mM procaine. This suggests that there may be differences in the mechanisms whereby methylxanthines and ryanodine deplete energy stores and evoke contractures in amphibian skeletal muscle.
Hays
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ET
School of Natural and Health Sciences, Barry University, Miami, FL 33161.
Sanchez
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K
Verrier
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004734:Energy Metabolism / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D011343:Procaine / Q000494:pharmacology; D011894:Rana pipiens; D012433:Ryanodine / Q000494:pharmacology*; D013806:Theophylline / Q000494:pharmacology*
D010725:Phosphocreatine; D012433:Ryanodine; D011343:Procaine; D000255:Adenosine Triphosphate; D013806:Theophylline