FIG. 3.

Changes in Fura-2 and Mag-fluo-4 fluorescence are consistent with the expected changes in PHM1-41 myometrial cell ([Ca²⁺]_i) and ([Ca²⁺]_L), respectively. Cells loaded with the dyes were exposed to (A) OT (100 nM), (B) thapsigargin (TG, 100 nM), or (C) CPA (10 μM) in the absence of extracellular Ca²⁺. After Ca²⁺ changes stabilized, cells were exposed to Ca²⁺-free buffer (0 Ca, blue line) or 1 mM extracellular Ca²⁺ (green line) in A and B. C) CPA was added as described for thapsigargin and was then removed from one group of cells by washing with calcium-free buffer (wash) at the time indicated. Both the washed (green line) and unwashed (blue line) cells were then exposed to 1 mM extracellular Ca²⁺. Additions of OT, CPA, wash, and Ca²⁺ are indicated by arrows. Each line represents an average of the responses of 35–40 cells in one of three similar experiments.