Figure 2.

Quinic acid (QA) triggers fast cytosolic Ca²⁺ rise and modulates the frequency of glucose‐induced cytosolic Ca²⁺ peaks. (a) Cytosolic YC3.6_cyto signal recorded at 535 nm. Example of single‐cell traces of INS‐1E cells, transfected with the cytosolic Ca²⁺ sensor YC3.6_cyto cells at 2.5‐mM glucose and stimulated with (b) Krebs–Ringer bicarbonate HEPES buffer (KRBH; control [Ctrl], n = 5) or (c) 100‐μM QA (n = 5). Representative traces of INS‐1E cells, transfected with YC3.6_cyto and stimulated with (d) KRBH (Ctrl, n = 5) or (e) QA (n = 5) and then with 16.7‐mM glucose. K_ATP channel was activated with 100‐μM diazoxide (Diaz), and then cells were depolarized with addition of 30‐mM KCl (KCl). (f) Statistical evaluation of the total Ca²⁺ transiting during 5′ stimulation, calculated by integrating the AUC, during KRBH or 100‐μM QA stimulation. (g) Statistical evaluation of the frequency of peaks during glucose stimulation (16.7 mM). (f, g) Values shown are means ± SEM from 97 cells (n = 5; Ctrl) and 93 cells (n = 5; QA); *P <.05, significant effect of QA; Student's t test