Figure 3.

IGF-1 did not potentiate methacholine (MCh)-induced contraction of rat or human tracheal smooth muscle. Methacholine-induced smooth muscle contraction was measured in rat tracheal rings before and after a 30-min (A) or 2-h (B) exposure to 100 ng/mL rat IGF-1 and in human tracheal smooth muscle strips before and after a 30-min exposure to 20 ng/mL human IGF-1 (D). C: methacholine-induced smooth muscle contraction in rat tracheal rings was also measured before and after a 30-min treatment with PBS (vehicle for IGF-1). Methacholine-induced contractions were normalized to contraction induced by 100 mM KCl. Data shown are means ± SE of two replicates each from 3 rat tracheas (n = 3; A–C) and 2 replicates each from 5 human donors (n = 5; D). PBS, phosphate-buffered saline.