A novel phasic contraction induced by dithiothreitol in frog skeletal muscle.
1. Dithiothreitol (DTT), at 50-100 mM, induced a phasic reversible contraction of frog skeletal muscle. 2. Exposure of single fibers to nifedipine (20 microM), an L-type Ca2+ antagonist, blocked the twitch and tetanus tensions but never affected the DTT-induced contraction. 3. DTT also produced a phasic contraction in fibers where voltage sensors were inactivated in the presence of high K+ concentration (190 mM). 4. A fiber was mechanically skinned after observation of DTT-induced contraction. The skinned fiber contracted in response to a DTT concentration similar to that required to produce contraction in intact fibers before skinning. 5. In skinned fibers, DTT, at 100 or 200 mM, inhibited the accumulation of Ca2+ by SR, but not Ca2+ ATPase activity. 6. These results suggest that a high concentration of DTT triggers Ca2+ efflux from the SR through action on the Ca2+ release channel and/or closely associated proteins, such as triadin and FK-506 binding protein.
Oba
T
T
Department of Veterinary Biosciences, College of Veterinary Medicine, Ohio State University, Columbus 43210, USA.
Nihonyanagi
K
K
Tangkawattana
P
P
Yamaguchi
M
M
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D011896:Rana temporaria; D013439:Sulfhydryl Reagents / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D013439:Sulfhydryl Reagents; D000252:Calcium-Transporting ATPases; D009543:Nifedipine; D002118:Calcium; D004229:Dithiothreitol