Neuromuscular blocking effect of thiamphenicol on frog rectus abdominis muscle.

1. In the present study, thiamphenicol caused a significant fall in ACh-induced frog rectus abdominis muscle contraction peaks and significant rightward shifts of the contractile response curves in a dose-dependent manner. 2. In addition, the maximal ACh response of muscle could not be obtained in presence of thiamphenicol. On the other hand, thiamphenicol did not alter KCl-induced contractions of the muscle at the same concentrations. 3. In contrast chloramphenicol did not cause any significant change in ACh-induced contraction peaks. 4. These results have suggested that thiamphenicol may have a neuromuscular blocking effect on frog rectus abdominis muscle.