title: Comparison of the effects of caffeine and a 2-alkyl-1,2,3-benzotriazinium iodide on frog rectus abdominis.
abstract: 1 The mode of action of 2-n-propyl-4-p-tolylamino-1,2,3-benzotriazinium iodide (TnPBI), which induced contractures of frog rectus abdominis muscle, was investigated. 2 TnPBI caused contractures of frog rectus abdominis when the muscle had been depolarized with potassium chloride. 3 Experiments with TnPBI and caffeine in calcium-free Ringer suggested that both compounds produce contractures by releasing intracellular bound calcium. 4 It is suggested that at least two calcium stores are involved, one of which is sensitive to caffeine while both are sensitive to TnPBI.
mesh_terms: D000818:Animals; D001001:Anura; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D004347:Drug Interactions; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects*; D011894:Rana pipiens; D014227:Triazines / Q000494:pharmacology*
chemical_list: D014227:Triazines; D002110:Caffeine; C015481:2-n-propyl-4-4-tolylamino-1,2,3-benzotriazinium; D002118:Calcium