Spontaneous, rhythmic myoelectric activity induced by scorpion neurotoxin, reduced [calcium]0 and cadmium in chick striated muscle.

The cellular electrical activity accompanying the very slow resting-tension oscillation (period 4-13 min) in chick skeletal muscle caused by scorpion neurotoxin, reduced [Ca2+]0 and Cd2+ was investigated. All three oscillogenic treatments were found to induce spontaneous, periodically recurring, electrical activation of muscle cells, including periodic bursting activity of individual cells. The period of the recurrent electrical activation approximated the period of the resting-tension oscillation. The data suggest that the three oscillogenic treatments act by way of a common mechanism, possibly a critical Ca2+ moiety, to effect the periodic electrical activation of the cells. Analysis of single cell and group discharge activity suggests that the cells are coupled by non-specific, electrotonic interactions, resulting in the integration of their individual periodic activities into a resting-tension oscillation of the whole muscle.