COMPARISON OF THE EFFECTS OF CAFFEINE AND A 2-ALKYL-1,2,3-BENZOTRIAZINIUM IODIDE ON FROG RECTUS ABDOMINIS

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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.

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