Effects of short-chain fatty acids (SCFAs; acetate, propionate, or butyrate) on fluorescent staining ratio of filamentous and globular actin (F/G actin) in human airway smooth muscle (HASM) cells. A: effects of acetate, propionate, or butyrate (10 mM; n = 6) on stress fiber formation in HASM cells. Data are means ± SE. *P < 0.05 compared with basal. B: effects of acetate, propionate, or butyrate (10 mM; n = 6) on acetylcholine (ACh; 1 µM)-induced stress fiber formation in HASM cells. An increase in F/G actin indicates an increase in filamentous actin, which is a component of the cytoskeletal contribution to smooth muscle cell contraction. Data are means ± SE. *P < 0.05 compared with ACh alone.