“Again carbachol was found not to influence the Ca metabolism.2.In the presence of elevated [Ca++]0 (8 mM) or of caffeine (10−3–5·10−3 M) the ACh induced contractures were potentiated and their time courses were prolonged.”
“If the … or caffeine , which itself did not … in the presence of ACh , a sustained increase in tension was induced and the time course of twitch contractions was considerably prolonged.3.… ACh or caffeine nor the addition of calcium to the bathing medium were able to produce a contracture.”