Effects of ruthenium red on excitation and contraction in muscle fibres with Ca2+ electrogenesis.

The effect of ruthenium red (RR) on the electrical and contractile responses, membrane Ca currents, staining patterns of the external and internal membrane system were tested in intact and mechanically skinned muscle fibres of the crayfish Astacus fluviatilis. The following results were obtained: 1. Depression of the contractile responses following membrane depolarization (twitch, tetanus, potassium contractures).

[Excitation-contraction coupling in isolated muscle fibers with calcium electrogenesis preserved in a culture medium].

The aim of the present work was to check changes in functional characteristics of isolated muscle cells, operating on the calcium electrogenesis principle, while kept in culture media for several days. Skeletal muscle cells of the crayfish Astacus fluviatilis were used to study potassium/caffeine contractures and single/tetanic contractions; simultaneous electrical and mechanical responses were recorded by the microelectrode technique, and kinetics of calcium ionic currents was studied under vaseline-gap voltage clamp. In cultured fibers, active membrane responses and calcium current kinetics remained unchanged, or slightly increased, whereas contractile responses were substantially reduced.