Figure 4.

AMP-activated protein kinase (AMPK) activation on intracellular Ca²⁺ and endoplasmic reticulum (ER) Ca²⁺ in cultured vascular smooth muscle cells (VSMCs). After being loaded with Indo-1/AM dye, the cells were stimulated with ionomycin (10 μmol/L), which triggers Ca²⁺ release from the ER. A, 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) and metformin suppress the rise of intracellular [Ca²⁺]_i, whereas they increase Ca²⁺ in the ER. *P<0.05 Tunicamycin vs vehicle; #P<0.05 AICAR or metformin plus Tunicamycin vs Tunicamycin alone; n=5. *P<0.05 Tunicamycin vs vehicle; #P<0.05 Tunicamycin vs Tunicamycin plus AICAR or metformin. B, Effects of compound C on ionomycin-induced Ca²⁺ release and intracellular Ca²⁺ store; *P<0.05 compound C vs vehicle; n=6, *P<0.05 compound C vs vehicle. C, Increased levels of intracellular Ca²⁺ and decreased Ca²⁺ in ER in VSMCs derived from AMPKα2^−/−; AMPKα2^−/− vs wild-type (WT); n=7; *P<0.05 WT vs AMPKα2^−/−. D, Increased [Ca²⁺]_i/relative fluorescence units (RFUs) in VSMCs from AMPKα2^−/− mice. AMPKα2^−/− vs WT. n=8. Statistical analysis was performed by using a 2-tailed Student t test between 2 groups.