Fig. 7.

Dependence of FASIS on Ca_V opening – FASIS in INS-1E-cells was stimulated with 15 μM PA (15 μM i.e. 0.1 % BSA, 1.4 nM free PA; A–E,G,H) in typical single-cell recordings with additions of agents or glucose as indicated. (A–I) GCaMP6 fluorescence intensity records are shown for typical single-cell confocal monitoring of cytosolic Ca²⁺-oscillations [Ca²⁺]_c(t) in KRH medium containing 3 mM glucose and induced with PA (A–E,G,H) or 1 μM Agonist II (I). Additions of 15 μM PA are indicated by arrows, as well as additions of 5 μM nimodipine (A), 2 μM r-BEL (B), 2.5 μM etomoxir (C); 10 nM SkQ1 (D), and 2 μM GW1000 (H). In panel E), glucose was adjusted to 25 mM after 30 min to probe FASIS at high glucose. In panel F), no PA was added, but step-wise adjustments of glucose to 5, 7, and 9 mM were performed, just probing for GSIS. Panel G) shows the absence of both FASIS and GSIS (at 11 mM glucose) in INS-1E overexpressing catalase (bottom plot) as compared to cells expressing the empty vector (top plot). 30 mM KCl was added at the end.

Panels (J–O) show the peak analyses of Ca²⁺-oscillations – N = number of records in individual cells with 15 μM PA (1 μM Agonist II in O) are indicated, as well as the number of records with an inhibitor/agent N_inh that they were compared to (N/N_inh): J) 8/8; K) 51 (8000 peaks); 23 for 3 mM glucose and 10 for 9 mM glucose; L) 6/6; M) 13/12; N) 20/20; O) 5; 5 for 11 mM glucose. Note that all available FASIS data are summarized in the leftmost histogram of panel K).