“3 Caffeine (0.1–10 mm) inhibited, in a concentration‐dependent manner, contractions induced by electrical stimulation, potassium‐rich (60 mm K+) solution, sodium‐free solution or oxytocin (22.5 nm).”
“4 In Ca2+‐free solution, various substances oxytocin , sodium orthovanadate and prostaglandin E2) evoked sustained contractions that were suppressed by caffeine (5–10 mm).”