[Pharmacological studies on a new cephamycin, MT-141. (2) Its effect on preparations of neuromuscular junction, smooth muscle organs and gastro-intestinal system].

The results for pharmacological experiments of MT-141 were as follows; Twitch tension of gastrocnemius muscle evoked by the stimulation of sciatic nerve was slightly reduced with 400 mg/kg MT-141 i.v. and upper doses. As the change was very small, however, it seems that MT-141 has no neuromuscular junction blocking action. Although MT-141 did not show any effects on most of isolated smooth muscle organs, only isolated tracheal muscle was somewhat relaxed with 10(-3) g/ml MT-141. The spontaneous motility of smooth muscle in situ was temporarily increased with 800 mg/kg MT-141 i.v. and upper doses. Two hundred mg/kg MT-141 showed no effect on the value of blood sugar and functions of kidney and liver. Any hemolysis did not appear even in the highest dose of 200 mg/kg MT-141 used in this experiment. From the present results and previous report (Krebe, M. et al., Jap. J. Antibiotics, in press), it seems that MT-141 is promised to be a highly safe and useful antibiotic agent in clinical use.