Fig. 3. Stimulation of Golgi Ca²⁺ release by the β₁-adrenergic signaling pathway.

(A) Effects of isoproterenol (ISO) (20-1000 nM) or ISO (0, 5 or 10 nM) plus IBMX, EHNA, milrinone (MIL) or rolipram (ROL) on the percentage of cells exhibiting Golgi Ca²⁺ release within a 3 minute line-scan (n=22-30 cells). (B) Line-scan of ARVM under control conditions and after introduction of ISO (plus ROL. (C) Effects of ROL or MIL + 10 nM ISO on Golgi Ca²⁺ release frequency (n=12-21 cells). (D) Effects of PDE 3 or 4 inhibition on Golgi Ca²⁺ release amplitude relative to 10 nM ISO alone (n=12-30 cells). (E-G) Effects of ROL, MIL, ISO, ROL+ISO and MIL+ISO on SR Ca²⁺ spark frequency, amplitude (F/F₀), and full duration at half maximum width (FDHM, n=13-25 cells). (H) Effects of ROL, MIL, ISO, ROL+ISO on the SR Ca²⁺ content assessed by application of caffeine (n=8 cells). (I) Effect of 8-CPT, ISO , 8-CPT+ISO, 8-CPT+ISO +KN93 and 8-CPT+ISO +U7322 on the percentage of cells exhibiting Golgi Ca²⁺ release (n=10-13 cells) (J) line-scan images before and after introduction of 8-CPT+ISO. (K) Effects of 8-CPT, ISO and ISO+8-CPT on Golgi Ca²⁺ release frequency (n=10-12 cells). (L) Effects of 8-CPT, ISO and ISO+8-CPT on Golgi Ca²⁺ release amplitude (n=10-12 cells). (M) Effects of 8-CPT, ISO and ISO+8-CPT on SR Ca²⁺ spark frequency relative to the mean control level (n=15-23 cells). (N) Effects of 8-CPT, ISO and ISO + 8-CPT on spark amplitude. (O) Effects of 8-CPT, ISO and ISO+8-CPT on Ca²⁺ spark duration (n=22-58 cells). (P) Effects of 8-CPT, ISO and ISO+8-CPT on the SR Ca²⁺ content, assessed by rapid application of caffeine (n=10-11 cells). In A-H data was obtained from 3-5 hearts per protocol. In I-P, data was obtained from 3-4 hearts per protocol. *p<0.05, ** p<0.01, ***, p<0.005.