title: Effects of deuterium oxide on mechanics and energetics of skeletal muscle contraction.
abstract: Mechanics and energetics of contraction were studied in isolated frog semitendinosus muscles (n = 15) in deuterium oxide (D2O) at 5 degrees C. Twitch force and energy liberation (heat + work) in 99.8% D2O-Ringer at lo were 4 +/- 0.8 and 22 +/- 1%, respectively, of control values. Tetanus force was slowed in development, and developed tetanus force was reduced to 89 +/- 7% of control values. With repeated tetanic contractions, the rate of force development increased, and peak force increased above control values in some muscles. The twitch was potentiated 10-fold (10 +/- 2) after repeated tetanic contractions. Energy liberation increased but not in proportion to force. Ca2+ cycling energy liberation or activation heat, estimated from stretched muscles, was 60 +/- 3% of control values. With maximum posttetanic twitch potentiation, the activation heat increased by 25 +/- 3%. Peak twitch force and energy liberation occurred at longer muscle lengths than in normal Ringer. After correcting for small differences in force development at lo and 1.38 +/- 0.01 lo, it was possible to estimate the effect of length per se on energy liberation. Under these conditions, there was an 8 +/- 2% decrease in energy liberation at 1.38 lo.
mesh_terms: D000200:Action Potentials; D000818:Animals; D001833:Body Temperature Regulation; D002118:Calcium / Q000378:metabolism; D003903:Deuterium / Q000494:pharmacology*; D017666:Deuterium Oxide; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009129:Muscle Tonus; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D011894:Rana pipiens
chemical_list: D003903:Deuterium; D017666:Deuterium Oxide; D002118:Calcium