Abstract
1. With the microsomes not preincubated with ATP, the incubation of the microsomes with Salyrgan for a certain period of time was required for obtaining a maximum inhibition of the relaxing activity of microsomes. When the microsomes were preincubated with ATP, the period was more extended than that in the former case. In the latter case, no spontaneous recovery of relaxing activity appeared by further incubation.
2. When raised to a concentration 1.0×10-5M, Salyrgan inhibited completely the relaxing activity of microsomes, but did not that of relaxing substance. Salyrgan inhibited completely the latter activity at high concentrations above 3.0×10-5M.
3. The relaxing action of EDTA or pyrophosphate was observed even in the presence of Salyrgan at high concentrations, at which the action of the relaxing substance was inhibited.
On the basis of these results, the mechanism of the inhibitory action of -SH reagents on the relaxing action of the microsomes and that of the action of the relaxing substance were discussed.
