Fig 1. TRPM7-mediated sustained Ca²⁺ influx is abrogated by cAMP elevation.

(A) Stimulation with bradykinin triggers a sustained influx of extracellular Ca²⁺ in cells overexpressing TRPM7 (black), lasting for several minutes. Control cells (grey) show only a single brief Ca²⁺ transient upon bradykinin stimulation that typically lasts approximately one minute. Calcium levels are expressed as arbitrary units (a.u.). (B) Pretreatment with PGE1 (dark grey) or IBMX/forskolin (lighter grey) prevents the sustained influx in TRPM7-WT overexpressing cells. (C) IBMX/forskolin stimulation abruptly terminates the TRPM7-mediated sustained Ca²⁺ influx (arrow). (D) Using the Epac-based FRET biosensor it was verified that both PGE1 and IBMX/forskolin treatment elevate cytosolic cAMP concentrations. (E) Simultaneous recording of cAMP using FLIM/FRET and Ca²⁺ with Oregon-Green BAPTA-1 demonstrates tight temporal relationship between cAMP elevation and termination of Ca²⁺ influx.