Arsenazo III calcium transients and latency relaxation in frog skeletal muscle fibres at different sarcomere lengths.

Publisher Website
Google Scholar
Abstract
Single, intact, frog muscle fibers were injected electrophoretically with a Ca2+-sensitive metallochromic dye, Arsenazo III, to a local concentration of 1.2-1.5 mmol/l. The onset of both the Ca2+ transient and latency relaxation occurred at virtually the same time in the twitch response and neither of those transition times was altered significantly with changes in sarcomere length from 2.4 to 3.0 .mu.m. The amount of activation Ca2+ released in dye-injected regions of fibers following a single stimulus was .apprx. 0.3 mmol/l at 2.4 .mu.m sarcomere length. The rate of rise and the amplitude of the Ca2+ transient were reversibly decreased with increase in sarcomere length from 2.4 to 3.0 .mu.m. That finding is reviewed in relation to other evidence indicating length dependence of the intracellular release and distribution of activation Ca2+ up to 3.9 .mu.m sarcomere length.