Mechanics of manganese ions-induced contraction of ileal longitudinal muscle in Ca(2+)-free, high-K+ medium.
1. Mn2+ (5 mM) evoked the contraction of ileal longitudinal muscle in a Ca(2+)-free, high-K+ (60 mM) medium. Metabolic inhibitors, such as iodoacetic acid or glucose removal, reduced the contraction by Mn2+ in the Ca(2+)-free, high-K+ medium, suggesting that the contraction by Mn2+ depends on energy metabolism. 2. By the abrupt decrease in length of the ileum during contraction 3 hr after the addition of 5 mM Mn2+ in Ca(2+)-free, high-K+ medium, a rapid decrease in tension was seen, and redevelopment of tension followed, which is indicative of an active state. 3. In the late phase, 5 hr after the Mn(2+)-induced contraction, a similar decrease in the length also caused a rapid decrease in tension, without however, a redevelopment of tension. This probably indicates that the myofilaments in this phase transferred to a state of static interaction.
Nasu
T
T
Department of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University, Japan.
Baba
K
K
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology*; D006224:Cricetinae; D005947:Glucose / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D008297:Male; D017895:Manganese Compounds / Q000494:pharmacology*; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D011188:Potassium / Q000502:physiology*
D002712:Chlorides; D007461:Iodoacetates; D017895:Manganese Compounds; D005947:Glucose; C025340:manganese chloride; D011188:Potassium; D002118:Calcium; D019807:Iodoacetic Acid