Fig. 5. Bis-phenol inhibits [Ca²⁺]_i oscillations. Application of 10 µM bis-phenol (bar above traces) to cells in which [Ca²⁺]_i oscillations were already established in response to progesterone caused some cells to arrest immediately (A, records from two cells) or gradually (B, records from two cells). Activity in some cells recovered upon washout of bis-phenol (shown by bar above A). (C) In half of the cells in which oscillations persisted in the presence of 10 µM bis-phenol there was a significant prolongation of [Ca²⁺]_i peaks (records from two cells from same experiment as A and B). (D) Mean oscillation transients (mathematical averages of three oscillation cycles synchronised to peak [Ca²⁺]_i) from two cells. Transients generated before () and during () superfusion with 10 µM bis-phenol (b-p) have been overlaid to show the change in kinetics. Application of the drug extends the [Ca²⁺]_i, peak, apparently revealing two phases of Ca²⁺ clearance. (E) Application of 30 µM bis-phenol to cells in which oscillations persist in the presence of 10 µM bis-phenol results in immediate arrest at or near peak [Ca²⁺]_i. Records from two cells are shown. (F) Application of bis-phenol (40 µM) caused immediate arrest of [Ca²⁺]_i oscillations in cells superfused with `Ca²⁺-free' sEBSS (no added Ca²⁺). Records from two cells are shown. Under these conditions, upon cessation of oscillation [Ca²⁺]_i settled at a level at or below that occurring during oscillation troughs (compare to panels A, B and E).