[Effect of phalloidine on the contractile properties of glycerinized skeletal muscle].

The phalloidin addition (20--30 mkg/ml) is shown to be followed by complex transient of isometric tension of fibres in low Ca++ concentration. The process is accelerated by the temperature increase. The phalloidin treatment does not cause the loss of contractility and Ca++-sensitivity of isometric tension. The treated fibres lost their ability to work in an autooscillation mode at 20--23 degrees C but were in condition to do this at the temperatures higher than 30 degrees C. The mechanical properties of rigor fibres as well at the myosin aggregation dependence on ionic strength were not markedly changed after the treatment. The results make it possible to conclude that the autooscillation mode of contraction is due to some feedback via I-filaments. The actin modification by phalloidin disturbs this feedback.