Figure 3

I _osc and T _in responses activated by agonist stimulation. A) Strength of I_osc elicited by first agonist application did not change by knockdown of STIM1 or STIM2, compared with that obtained in CNT oocytes; top traces are typical responses elicited by ACh, similar responses were obtained by FBS or ATP applications, and the graph shows the average I_osc responses obtained in oocytes held at −60 mV. B) Record illustrating the activation of T_in current obtained in an oocyte expressing the M1 receptor by a single ACh (100μM) application for 40’s (acute protocol). Oocytes were held at −10 mV while being superfused with NR solution and stepped to −100 mV for 4’s every 40’s; sudden hyperpolarization generated T_in current responses that follow consistent kinetics with a peak amplitude response at 280-360’s (c); after that the response was washed out with a similar time course. C) Shows the T_in current during the steps from −10 to −100 mV indicated with letters in panel B). D) A similar T_in current response elicited in an oocyte from the same frog that was pre-incubated with 1μM ACh for 4 h (long-lasting protocol), then monitored with the same electrical recording parameters and stimulated with 100μM ACh. E) Shows the T_in responses indicated with the same letters as in D). In this protocol T_in current was consistently activated from the beginning of the record, and a transient inhibition of the response was noted during application of the agonist (b); after that, T_in recovered and remained fully activated for a long period of time. Similar responses were obtained using oocytes expressing P2Y receptors and stimulating with ATP.