The effect of trifluoperazine on muscle tension and cytoplasmic Ca2+ level in guinea pig ileum.
In guinea pig ileal muscle strips, trifluoperazine (TFP) inhibited the high K+-induced contraction with an IC50 of 1.9 microM and the Ca2+-induced contraction in skinned fiber with an IC50 of 44 microM. TFP decreased the high K+-induced increase in cytoplasmic Ca2+ level at the concentration 3 microM, which did not inhibit the contraction in skinned fiber. It is suggested that the inhibitory effect of TFP on the high K+-induced contraction is mainly due to the decrease in cytoplasmic Ca2+.
Hori
M
M
Department of Veterinary Pharmacology, Nippon Veterinary and Zootechnical College, Tokyo, Japan.
Shimizu
K
K
Nakajyo
S
S
Urakawa
N
N
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D011190:Potassium Cyanide / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014268:Trifluoperazine / Q000494:pharmacology*
D014268:Trifluoperazine; D009543:Nifedipine; D011190:Potassium Cyanide; D002118:Calcium