S. Lynn et al., A NOVEL RYANODINE-SENSITIVE CALCIUM-RELEASE MECHANISM IN CULTURED HUMAN MYOMETRIAL SMOOTH-MUSCLE CELLS, FEBS letters, 330(2), 1993, pp. 227-230
In cultured human myometrial cells application of caffeine (1-30 mM) d
id not result in an elevation of intracellular Ca2+ ([Ca2+]i). Caffein
e was found to reversibly inhibit both spontaneous and agonist-induced
repetitive rises in [Ca2+]i Possibly as a consequence of its ability
to interfere with the binding of inositol trisphosphate (IP3) to the r
eceptor on the sarcoplasmic reticulum. Brief applications of ryanodine
(1-10 muM) were observed to elevate [Ca2+]i and repeated exposures to
ryanodine could elicit Ca2+ transients of similar magnitude. Ryanodin
e was also observed to mobilise Ca2+ in cells bathed in nominally Ca2-free solution. These observations suggest the presence of a novel typ
e of ryanodine-sensitive Ca2+-induced Ca2+ release (R-CICR) system in
human myometrial cells.