抄録
EDTA and six analogues were tested for their relaxing action on glycerinated psoas muscle fibers, their potentiating effect on myosin ATPase and their synergistic action with inorganic polyorthophosphate on glycerinated fibers.
1. The relaxing action of the chelating compounds was shown to have any quantitative correlation with their chelating action on neither Ca nor Mg. GEDTA, which has practically no chelating capacity for Mg under the experimental conditions, showed a remarkable relaxing effect, several times as strong as EDTA.
2. The potentiating action of the chelating agents on myosin-A ATPase has no correlation with their chelating effect on Ca, but showed some correlation with their chelating capacity for Mg.
3. The lengthening of glycerinated muscle fibers by inorganic polyorthophosphate was markedly accelerated by EDTA and its analogues; thus elongated fibers were found without contractility. This action did not parallel the chelating activity.
4. The abovementioned three actions of chelating agents showed no correlation with one other.
The authors wish to express their thanks to Prof. H. Kumagai for his encouragement and to Dr. S. Watanabe at the Dartmouth Medical School for his discussions.
